UPS SIMPLY

Uninterruptible Power Supply (UPS) Software Saves Time and Money

noreply@blogger.com (ADMIN) — Mon, 12 Mar 2012 23:59:00 +0000

As we mentioned in many posts before, using an Uninterruptible Power Supply (UPS) is necessary especially in case of Utility Power fluctuations and other power related issues. The need of powerful power protection systems and uninterruptible power supplies is essential everywhere from home to small business, governmental organizations, hospitals, airports, critical missions, and to any place need a power source with a constant voltage level.

Because of the importance of having highly advanced Uninterruptible Power Supply (UPS), you have to put these power protection systems in good weather conditions. Also you should offer professional maintenance and safety for these systems. One of the most effective tools to safe the Uninterruptible Power Supply (UPS) is using an innovative and highly advanced UPS Software.

Most of modern UPS models come with their own software installed by the manufacturer. These software may be UPS monitoring software or UPS control software. The main function of these software is to make you updated with the status and technical details of your UPS system. Also, they inform you periodically by messages and alerts about backup batteries and other issues that may occur.

Conclusion:

Having Uninterruptible Power Supply (UPS) Software is a powerful tool for the safety and long-life of UPS systems. Thus, they may contribute in saving your time and money by monitoring and controlling the effective parameters of your UPS systems.

According to your system requirements, you can select between various types of UPS Software. One of the most famous UPS Software is UPS Assistant Program (you can read more about UPS Assistant Program in this post: How To Manage Your Uninterruptible Power Supply with UPS Assistant ).

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Uninterruptible Power Supply protects your Laptop

noreply@blogger.com (ADMIN) — Thu, 01 Mar 2012 13:03:00 +0000

It depends on you! if you need non-stop operation of your Personal Computer or laptop, you have to use an uninterruptible power supply (UPS). UPS will protect your computer not only if the main power supply completely shut down but it may also protect your computer and its peripherals (such as printers, scanners, monitors, etc.) against power surges or low voltage tricks which could harm your electronic devices.

It is a fact, power failure can happen at any time 24 hours a day. Regardless of what the reason of this failure, using a backup power supply like UPS is very important to keep computer systems running all the time.

UPS has a great role if you have a web-based business or any other business that depends on computer systems require immediate access to rates, changes, inventories, consumer data, or other information can't be reached without computer access.

Conclusion:

1- UPS may save your money by protecting your data and computer hardware.

2- Whether or not you have got a home business or simply a large business, you can't work without a power supply.

3- You have to verify and maintain your UPS system every quarter to guarantee they are functioning properly. Also you have to check out the UPS Batteries and change them in the suitable time.

4- Most of UPS models have a test button to check out its functionality status.

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How to properly maintain and manage UPS batteries

noreply@blogger.com (ADMIN) — Mon, 12 Dec 2011 11:37:00 +0000

Always follow safe work practices when maintaining battery systems.

It’s a well-known fact in the industry that the battery is the most vulnerable part of a UPS. In fact, battery failure is a leading cause of load loss. Understanding how to properly maintain and manage UPS batteries can not only extend battery service life, but it can also help prevent costly downtime.

The most common type of battery used in today’s UPSs is the valve-regulated lead acid (VRLA) battery, also known as a sealed or maintenance-free battery. VRLA batteries are sealed, usually within polypropylene plastic, which offers the advantage of not containing any sloshing liquid that might leak or drip. Because water cannot be added to VRLA batteries, recombination of water is critical to their life and health. In addition, any factor that increases the rate of evaporation or water loss, such as temperature or heat from the charging current, reduces the life of the battery.

Let’s take a look at some of the most frequently asked questions when it comes to UPS battery maintenance.

1. What is the “end of useful life?”

The IEEE defines “end of useful life” for a UPS battery as being the point when it can no longer supply 80% of its rated capacity in ampere-hours. When your battery reaches 80% of its rated capacity, the aging process accelerates, and you should replace it.

2. Is there any difference between the batteries used by smaller UPSs (250VA to 3kVA range) and the ones used by larger UPSs?

While basic battery technology — and the risks to battery life — remain the same regardless of UPS size, there are some inherent differences between large and small applications. First, smaller UPSs typically have only one VRLA battery that supports the load and requires maintenance. As systems get larger, increasing battery capacity to support the load gets more complicated. Larger systems may require multiple strings of batteries, introducing complexity to battery maintenance and support. Individual batteries must be monitored to prevent a single bad battery from taking down an entire string and putting the load at risk. In addition, as systems get larger, the use of wet-cell batteries become much more common.

3. My UPS has been in storage for more than a year. Are the batteries still good?

As batteries sit unused, with no charging regimen, their life will decrease. Due to the self-discharge characteristics of lead-acid batteries, it is recommended you charge them every three to four months of storage. Otherwise, permanent loss of capacity will occur between 18 and 30 months. To prolong shelf life without charging, store batteries at 10°C (50°F) or less.

4. What is the difference between hot-swappable and user-replaceable batteries?

Hot-swappable batteries allow the batteries to be changed out while the UPS is running. User-replaceable batteries are usually found in smaller UPSs and require no special tools or training to replace. Batteries can be both hot-swappable and user-replaceable.

5. How is battery runtime affected if I reduce the load on the UPS?

The battery runtime will increase if the load is reduced. As a general rule, if you reduce the load by half, you triple the runtime.

6. If I add more batteries to a UPS, can I add more load?

Adding more batteries to a UPS can increase the battery runtime to support the load. However, adding more batteries to the UPS does not increase the capacity of the UPS. Be sure your UPS is adequately sized for your load, then add batteries to fit your runtime needs.

7. What is the average lifespan of UPS batteries?

The standard lifespan for VRLA batteries is three to five years. However, expected life can vary greatly due to environmental conditions, number of discharge cycles, and adequate maintenance. Have a regular schedule of battery maintenance and monitoring to ensure you know when your batteries are reaching the end of their life.

8. Does the UPS need to have a load on it to charge its batteries?

Generally, the UPS does not require a minimum load to charge its batteries. Once connected to a standard supply of electricity (via input plug or hardwiring), your UPS should charge its batteries regardless of how much load, if any, is attached to it.

9. How can you ensure UPS batteries are in good condition and have maximum holdover in the event of a power failure?

You should have the UPS and its batteries thoroughly inspected and tested by a trained field technician. On smaller UPS models, you can often initiate a self test of the unit by pressing a button on the front panel.

10.What is thermal runaway?

Thermal runaway occurs when the heat generated in a lead-acid cell exceeds its ability to dissipate that heat, which can lead to an explosion, especially in sealed cells. The heat generated in the cell may occur without any warning signs and may be caused by overcharging, excessive charging, internal physical damage, internal short circuit, or a hot environment.

11.Why do batteries fail?

Batteries can fail for a multitude of reasons, but the most common causes include:

· High or uneven temperatures

· Inaccurate float charge voltage

· Loose inter-cell links or connections

· Loss of electrolyte due to drying out or a damaged case

· Lack of maintenance/aging.

12.How is battery performance typically measured?

Batteries are generally rated for 100+ discharges and recharges. However, many batteries show a marked decline in charging capacity after as few as 10 discharges. The lower the charge the battery can accept, the less runtime it can deliver. Look for batteries with a high-rate design that sustains stable performance for a long service term.

13. What should a UPS service plan cover?

When evaluating service plans, pay special attention to what is and isn’t covered. Support agreements and warranties for large UPS models usually cover internal electronics only, with battery coverage available as an optional extra. A strong, comprehensive service plan should cover all of the following:

UPS electronics parts and labor coverage: This covers a UPS’s basic electrical components, excluding the battery.

UPS battery parts and labor coverage: To prevent UPS failure, batteries should be replaced at least every 5 years. Batteries that are discharged frequently or used in a warm environment should be replaced more often.

Preventive maintenance: Preventive maintenance visits allow field technicians to annually inspect, test, calibrate, and upgrade UPS and/or battery components, ensuring factory-specified performance. You might also consider adding remote monitoring services to your maintenance plan.

Highlights:

Factors Affecting Battery Life

All UPS batteries have a limited service life, regardless of how or where the UPS is deployed. Although determining battery life can be tricky, there are four primary factors that contribute to a battery’s overall lifespan.

Ambient temperature

Because the rated capacity of a battery is based on an ambient temperature of 25°C (77°F), any variation can affect performance and reduce battery life. For every 8.3°C (15°F) average annual temperature above 25°C (77°F), the life of the battery is reduced by 50%.

Battery chemistry

UPS batteries are electro-chemical devices whose ability to store and deliver power slowly decreases over time. Even if all guidelines for storage, maintenance, and usage are followed, batteries will still require replacement after a certain period of time.

Cycling

After a UPS operates on battery power during a power failure, the battery is recharged for future use, which is called the discharge cycle. At installation, the battery is at 100% of its rated capacity, but each discharge and subsequent recharge slightly reduces the relative capacity of the battery. Once the chemistry is depleted, the cells fail and the battery must be replaced.

Maintenance

For larger UPS models, service and maintenance of batteries are critical to the reliability of the UPS. Periodic preventive maintenance not only extends battery string life by preventing loose connections and removing corrosion, but it can help identify ailing batteries before they fail. Even though sealed batteries are sometimes referred to as “maintenance-free,” they still require scheduled service, as “maintenance-free” refers only to the fact that they do not require replacement fluid.

Source: http://ecmweb.com/

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Comparing Rotary and Online UPS Power Supply Types

noreply@blogger.com (ADMIN) — Fri, 09 Dec 2011 12:33:00 +0000

Online UPS systems

More than ever, uninterruptible power supply (UPS) systems of today need to possess high levels of reliability and security. They should deliver optimum performance, making sure that power supply to loads is steady and regulated. As high-end computer and telecommunication equipments continue to rely on these systems for nonstop operation, the UPS power supply industry must continue to evolve their designs and provide consumers with the safest and best systems available. Two of the best UPS systems at present are said to be the rotary and online types.

Rotary UPS systems came into the limelight in the recent years. These are mechanical uninterruptible power supply machines that convert kinetic energy to electric energy to make systems run. Its design competes with static online UPS systems of today and boasts improved efficiency. Manufacturers say that rotary uninterruptible power supplies even achieve higher MTBF (Mean Time between Failures) values and generate fewer harmonic than online types. Lesser harmonic levels are good because harmonics can be as damaging to critical loads as sudden partial of complete power cut off. Keeping harmonic levels to a minimum thus help in protecting equipments from hardware failure or data corruption. MTBF, meanwhile, is one of the standard indicators of UPS power supply reliability because it stands for the mean operational time (in hours) between system power-up and shut down due to failure. Rotary UPS systems are also believed to be suitable for loads with leading power factors (i.e. high-end servers) because they have superior fault clearance capabilities.

However, rotary UPS systems have their share of disadvantages. For one, because they are mechanical devices, they have complex installation and maintenance procedures. They also require lubrication, which can be difficult. Equipments can become sensitive to working temperatures, which may result to more frequent maintenance. Rotary UPS usually have high MTTR (Mean Time to Repair) values and it may take days to replace or repair a broken uninterruptible power supply unit. Meanwhile, installing them is complex work because mechanical devices often have noise, vibration, and exhaust gas issues. Another disadvantage of rotary UPS systems is their bulkiness. Their huge size and weight generally demands larger areas than static online UPS and so expanding systems may prove to be a hassle.

Rotary UPS systems

In comparison, static online UPS systems are typically easy to install and are far less expensive than rotary types. They can be effortlessly configured in parallel and redundant designs, if there is a need for more security and reliability. Though rotary uninterruptible power supplies have the edge in terms of MTBF and harmonics values, online UPS try to keep up by incorporating rectifiers and filters in new device designs. They also attempt to develop better systems so that loads with leading power factors can be accommodated. Modularity and flexibility of online uninterruptible power supply systems is one of its great advantages as well because expanding them is straightforward and hassle-free. Ripping out and replacing noisy rotary units is almost always bothersome. Expanding static online UPS power supply types is also cost effective.

Source: http://EzineArticles.com

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Calculating UPS Battery Backup Times

noreply@blogger.com (ADMIN) — Thu, 08 Dec 2011 11:45:00 +0000

A UPS allows users to protect their work from sudden power interruptions.

As a safeguard against losing work to blackouts and other power failures, many computer users are turning to uninterruptible power supplies (UPS), which consists of a battery integrated into a surge protector or other voltage adapter. Each UPS has a specific volt-ampere (VA) rating, which is an expression of the maximum AC power it can supply. The length of time for which the UPS can support a particular appliance's electrical load depends on the efficiency of its DC-to-AC inverter, its effective output voltage and the capacity of the battery.

Instructions

Determine the efficiency or "power factor" for your UPS's DC-AC converter. This information is normally found in the "Technical Specifications" section of the UPS-enabled device's Owner's Manual. If you can't find the efficiency there, try searching the manufacturer's website or send on inquiry to their customer service email address.

Determine the capacity (in ampere-hours or "AH") for each of the UPS's backup batteries. To approach the voltage levels of an electrical outlet, most UPS models will link several 12-volt, sealed lead-acid batteries in a series. Some manufacturer's will include the capacity of each battery in the Owner's Manual under "Specifications." If you cannot find the battery capacity listed in any of the UPS's literature, you'll have to carefully remove one of the panels from the UPS's housing to see the capacity printed on the batteries themselves.

Add together the voltages from all of the batteries from Step 2. This will give you the combined DC voltage output for the UPS. Note: do not add together the capacities, as that value in unaffected by the series circuit configuration.

Multiply the combined DC voltage (from Step 3) by the UPS's power factor (from Step 1). This result will represent the effective AC voltage output by the UPS.

Determine the voltage and amperage ratings for the appliance that the UPS will be backing up. These values are typically found either printed on the back of the appliance or published in the "Technical Specifications" section of the Owner's Manual. As a last resort, you can search of this data in the "Products" section of the manufacturer's website.

Multiply the appliance's voltage (from Step 5) by its amperage (from Step 5) to calculate its power consumption in volt-amperes (VA).

Divide the appliance's power consumption (from Step 6) by the UPS's AC output voltage (from Step 4). This will give you the current (in amperes) the appliance will draw from the UPS.

Divide the single battery capacity (from Step 1) by the current draw (from Step 7). This will give you the ideal maximum backup time for the UPS, in hours.

Source: http://www.ehow.com/

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How to Install an Uninterruptible Power Supply

noreply@blogger.com (ADMIN) — Wed, 07 Dec 2011 11:25:00 +0000

Install an Uninterruptible Power Supply

Power fluctuations and sudden loss of power are issues that can both result in serious damage to computers and their peripheral devices. An uninterruptable power supply, commonly abbreviated UPS, is a device that is designed to maintain a steady and constant source of electricity to your devices.

A UPS takes the power supplied from an outlet and stabilizes it before feeding electricity to the devices connected to the included outlets. In the event of a loss of power, the UPS switches from main power to a battery backup, which gives a user the chance to save any data and properly shut down the devices connected to it.

Instructions

Set the UPS device on a solid, level and dry surface close to both a power source and your computer equipment. To avoid overheating, place the UPS in a location where it can get adequate airflow.

Plug the UPS into a wall outlet and then connect all of your devices to the available outlets.

Press and hold the power button on the UPS for about two seconds. This will initiate a self-test procedure. Once the self-test is complete, your UPS will be ready to supply steady power to your devices. The internal battery will charge while your devices are in use.

Tips & Warnings

Do not overload the UPS with devices. Doing so can result in unsatisfactory performance and potential damage to the UPS.

Source: http://www.ehow.com/

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Enhance your Workplace Efficiency with Competent Range of Uninterruptible Power Supply

noreply@blogger.com (ADMIN) — Tue, 25 Oct 2011 10:09:00 +0000

Uninterruptible Power Supply (UPS) is a device used to provide clean, consistent, and continuous power supply to critical and sophisticated electrical devices that need continuous supply of power to function. Even a slightest of power disturbance can prove fatal for these devices, as these devices are quite susceptible and sensitive to power problems like sags and surges.

The significance of uninterruptible power supplies have been well understood across several industries like medical centers, data centers, and research institutes, where there is a strict requirement of clean and continuous power supply.

UPS is used to provide power to the electrical device at the time of main power supply failure. During blackout or sudden power failure the UPS powers the attached electrical device with the stored power. Therefore, uninterruptible power supplies ensure continuous functioning of the devices even in the case of power failure.

Uninterruptible Power Supply plays a vital role in improving the workplace efficiencies as office work environment to a great extent is dependent on electric supply, as today most of the offices work is carried out with the help of computers. Even the slight disturbance in the main power supply can hamper the work environment of the office.

To maintain efficiency of their employees it becomes essential for the offices to provide proper power protection devices and power backup devices to avoid any disturbance in the office work. Therefore, offices greatly rely on uninterruptible power supplies to provide their employees with good work environment. The increase in demand of uninterruptible power supplies have motivated manufacturers to come up with different make and model of UPS to cater different type of power requirements of both domestic as well as commercial clients.

People have quite a general perception about uninterruptible power supplies that these are used to power electrical devices in case of blackout, and this is not the only function that people attribute to it. But it is a fact that uninterruptible power supplies are known for performing several vital functions that ensure safe and smooth operation of several critical devices that requires clean and consistent power.

The UPS not only powers the device during power failure but it also maintains the consistent voltage to the attached devices.

Any unexpected fall in the current flow is well taken care of by the UPS as it saves the attached device from any unexpected power problems. The UPS immediately senses the sudden changes in the current flow and disconnects the attached devices from the main power supply and start supplying power to the devices till the electric supply returns to normal.

Source: http://www.articlesbase.com/

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UPS for Sufficient Power Backup and Safety of Devices

noreply@blogger.com (ADMIN) — Tue, 25 Oct 2011 09:28:00 +0000

High quality, uninterrupted and reliable power supply is vital for mission critical operations, data centers, server rooms, telecommunication, medical operations and military bases as well. Electrical and electronic equipments used at these places or for them are very sensitive and a power fluctuation can turn into a major loss for them. As far as high-quality and uninterrupted power supply is concerned, the concept of uninterruptible power supplies come into mind.

Known by different names like UPS systems, emergency power supply, standby power backup and inverters, such power supply and power protection devices are also considered as multifunctional devices. UPS or uninterruptible power supplies not only keep the power supply continue at a constant voltage level, but also protect sensitive electrical and electronic devices against different types of power problems.

Uninterruptible power supplies are available in different ranges from 300 VA to 6 MVA and more. These devices are capable enough to supply electric power from a few minutes to hours according to the power load and the devices. Depending on the requirement, uninterruptible power supplies are available in different power ranges from 300 VA to 800 kVA and more.

Such widely used power protection devices in the range of 350 VA to 800 VA are considered as perfect for the protection of domestic applications, small servers, workstations, PCs, terminals and EpoS (Electronic-point-of-Sale). In case of power fluctuation or power failure, these uninterruptible power supplies keep high-quality and reliable power supply maintained.

For everyday power problems, UPS devices in the range of 350 VA to 800 VA are perfect for the aforesaid systems. In addition to this, UPS devices in the power range of 500 to 2000 VA are perfect for servers as well as entire network. These power protection devices are also known as network size UPS systems.

Uninterruptible power supplies for server rooms are available in the range from 1500 VA to 10 kVA. Such uninterruptible power supplies protect server racks against power fluctuation and other types of power problems. You can get one or more according to the type of devices by simply placing your order online at any selected supplier. These power protection devices are also known as network size UPS systems.

Source: http://www.articlesbase.com/

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UPS (Uninterruptible Power Supply) installation and configuration

noreply@blogger.com (ADMIN) — Tue, 25 Oct 2011 08:42:00 +0000

An inexpensive way to prevent unscheduled downtime or data loss due to power problems is with a UPS or Uninterruptible Power Supply. However, a UPS by itself is not enough for proper operation. Hardware, software, and configuration together make up a UPS system that will recover from unexpected power loss or power fluctuations that can damage systems and peripherals.

Introduction

When considering data loss, system downtime and disaster recovery, backup methods are primarily discussed. There are many methods of preventing data loss, including clustering, backup, security and power conditioning. Proper power can prevent an initial disaster from ever occurring. Providing proper power can be in the form of an Uninterruptible Power Supply or UPS. A UPS has rechargeable batteries to supply emergency power in the event of immediate power loss. If the power loss is longer than the batteries can supply, then the UPS can signal the server to initiate a power down sequence to properly shutdown, preventing data loss. When power is returned the server can return to operation after having made a clean shutdown.

Other power related problems that occur can be minimized with the circuitry of a UPS. Voltage sags and spikes, brown outs and line noise (from other machinery like elevators, air conditioners or office equipment), can all be isolated by a UPS. These power related fluctuations can wreak havoc on systems and devices. For a relatively low cost a UPS can prevent downtime due to power anomalies.

Network UPS Tools

The Network UPS Tools (NUT) are a group of tools that are used to monitor and administer UPS hardware. NUT uses a layered scheme of equipment, drivers, server and clients. The equipment consists of the monitored UPS hardware. Drivers specific to the UPS hardware communicate or poll the UPS for status information in the form of variables. The driver programs talk directly to the UPS equipment and run on the same host as the server. The server upsdserves data from the drivers to the network. Clients talk to the upsdserver and initiate tasks with the status data.

As indicated by the name, Network UPS Tools, NUT is a network based UPS system that works with multiple UPSs and systems. One of the many features of NUT allows multiple systems to monitor a single UPS, not requiring special UPS sharing hardware connections. The master/slave relationship synchronizes shut-downs so the slaves can initiate power-down sequences before the master switches off UPS power.

This article details the installation and configuration of a single system with a UPS connected to the serial port of the system. This is the natural first step of getting NUT installed and configured. If the UPS will supply more than one system, the second and subsequent systems can be configured as slaves.

The NUT developers also have a different take on when the systems should be powered down. NUT will wait until the UPS is “on battery” and “low battery” before it considers the UPS “critical”. This philosophy gets the most out of the UPS batteries and will wait until the critical moment to initiate a power down sequence, just in case the power comes back on line. There is an option to override this behavior if desired with upssched, which can be found in the documentation. With the upssched utility, commands can be invoked based on UPS events.

In typical GNU/Linux fashion, NUT is not the only tool available for monitoring a UPS. Apcupsd is used for power management and control of APC model UPSs. There are also several graphical frontends for workstation class machines.

Preparing for installation

Prior to installing and using a UPS and its associated software, a few things must be in place. Since the system is going to be shutdown there must be a way to bring the system back up when power returns. The system BIOS needs to be configured correctly. Most modern BIOSes have an option to power-on when main power, now supplied by the UPS, is returned. Server system BIOSes will most likely support the “power on when power returns” option. If the BIOS does not support this option (more common with workstation class systems), a BIOS update may correct it. With servers configured headless, without a monitor or keyboard, there are also settings to ignore keyboard errors. Commonly these types of systems are administered via SSH or administration utilities like Webmin.

The UPS must also have the correct signal cable from the UPS to the system. With a USB type of UPS this is not a concern. A UPS that communicates via the serial port needs the correct signal cable that supports intelligent signaling between the UPS and system. See the UPS vendor for the correct cable or a custom cable can be built with information from the Network UPS Tools web site.

Installing NUT

The example system is running a basic install of Debian GNU/Linux V4.0 and utilizing an APC SmartUPS 700. Debian is an excellent, long term supported GNU/Linux, which is ideal for small enterprise deployments, as well as much larger environments. Different GNU/Linux distributions may install the software and configuration files in different directories. Since the server is configured without a GUI interface, all commands and configuration are done through the command line as the root user. Using the APT package tool, apt-get, the package nut can easily be installed:

# apt-get install nut

The package tool installs the NUT software, documentation, man pages and example configuration files. Debian specific documentation is found in the /usr/share/doc/nut/ directory.

Extensive NUT documentation can be found in/usr/share/doc/nut/docs/ and the example configuration files in /usr/share/doc/nut/examples/. Some of the documentation is compressed with gzip which can be uncompressed or viewed with the zcat utility.

# zcat /usr/share/doc/nut/README.Debian.gz | less

The configuration files exist in the /etc/nut/ directory.

Theups.conf configuration file contains the UPS definitions.

The UPS is defined with the [labsvr] entry.

The driver and port fields must be defined, the desc field is optional and describes the UPS. Additional UPS definitions can be configured in this file; however, this example is a single UPS and server configuration.

[labsvr]

driver = apcsmart

port = /dev/ttyS0

desc = "Lab Server"

The definition, between the square brackets, is user definable, with the exception of word default, since it is used by the Network UPS Tools. The correct driver name for your UPS can be found in the file/usr/share/nut/driver.list. For proper permissions to use the serial port the nut user must be added to the “dialout” group, and can be accomplished with the addgroup command. To manually test the configuration and to verify the configuration is correct theupsdrvctl (UPS driver controller) command is used. After verification the driver can be stopped.

# addgroup nut dialout

Adding user `nut' to group `dialout' ...

Done.

# /sbin/upsdrvctl start labsvr

Network UPS Tools - UPS driver controller 2.0.4

Network UPS Tools (version 2.0.4) - APC Smart protocol driver

        Driver version 1.99.8, command table version 2.0

Detected SMART-UPS 700 [QS0331213446] on /dev/ttyS0

# /sbin/upsdrvctl stop labsvr

Network UPS Tools - UPS driver controller 2.0.4

Stopping UPS: labsvr

Since this example is a single server, the access control list for server communication is minimal. Configuring the access control lists is accomplished in the configuration file upsd.conf. The ACL (access control list) all is defined with the netblock in CIDR format, the old style address/network format can also be used. Additionally the ACL localhost is defined. The ACCEPT field allows communication to the server for localhost and the REJECT field blocks all other access. Similar to other access control lists, flow goes from the top down. The ACCEPT is evaluated before theREJECT, if the REJECT line were before ACCEPT, localhost would meet the rule and not be allowed access.

ACL all 0.0.0.0/0

ACL localhost 127.0.0.1/32

ACCEPT localhost

REJECT all

The upsd.users configuration file is used to define users that have access to administrative commands. Here are defined the users and what access each user is allowed; each section begins with user names in brackets and continues to the next bracketed user or end of the file. The password field defines the user’s password. Theallowfrom field grants access based on the user’s source IP address, the values are defined in the ACL lists configuration fileupsd.conf. The upsmon field is set to either master or slave to allow the upsmon process to work.

[monmaster]

    password = p455w0rd

    allowfrom = localhost

    upsmon = master

The final configuration file upsmon.conf defines which systems theupsmon process will monitor, as well as how to shutdown systems when necessary. The MONITOR line defines the UPS to monitor. The first field is the UPS to monitor, in this case labsvr@localhost. The second field is the power value that defines the number of power supplies the UPS supplies. In simple configurations this is normally set to 1. The next two fields are the user name and password that were previously defined in upsd.users.

The last field will be eithermaster or slave process. A master process is one in which the process is running on the system that is plugged in directly and communicates with the UPS. A slave is a process that gets power from the UPS but doesn’t communicate directly to it.

MONITOR labsvr@localhost 1 monmaster p455w0rd master

POWERDOWNFLAG /etc/killpower

SHUTDOWNCMD "/sbin/shutdown -h +0"

The POWERDOWNFLAG defines a file name to be created in mastermode when the UPS needs to be powered off. This file is cleared when the system comes back up. Finally, SHUTDOWNCMD is the actual shutdown command performed enclosed in quotes.

After the configuration of the UPS and Network UPS Tools is complete, a couple of housekeeping tasks need to be accomplished. Since several of the configuration files contain user names and passwords, they will have permissions set so only the root user and nut group can read them with the following commands:

# chown root:nut /etc/nut/*

# chmod 640 /etc/nut/*

With Debian GNU/Linux, two items must also be changed in the file/etc/default/nut, START_UPSD and START_UPSMON are changed from “no” to “yes”.

START_UPSD=yes

START_UPSMON=yes

The nut init.d script can be run to start the UPS monitor tools and/var/log/syslog is checked to verify everything is running correctly.

# /etc/init.d/nut start

Starting Network UPS Tools: upsdrvctl upsd upsmon.

# tail /var/log/syslog

Sep 01 13:36:48 labserver apcsmart[2519]: Startup successful

Sep 01 13:36:48 labserver upsd[2520]: Connected to UPS [labsvr]: apcsmart-ttyS0

Sep 01 13:36:50 labserver upsd[2521]: Startup successful

Sep 01 13:36:50 labserver upsmon[2523]: Startup successful

Sep 01 13:36:50 labserver upsd[2521]: Connection from 127.0.0.1

Sep 01 13:36:50 labserver upsd[2521]: Client  monmaster@127.0.0.1 logged into UPS [labsvr]

To quickly poll the status of a UPS server, the upsc UPS client utility is used. The first example displays the value of the ups.statusvariable, which is OL (or “on line”), meaning the UPSlabsvr@localhost is on line power. If the value of ups.statuswere OB (“on battery”), then the UPS would be supplying battery power to the server. The second invocation displays all available variables and the values for labsvr@localhost.

# upsc labsvr@localhost ups.status

OL

# upsc labsvr@localhost

battery.alarm.threshold: 0

battery.charge: 100.0

battery.charge.restart: 00

battery.date: 08/02/03

battery.packs: 000

battery.runtime: 7860

battery.runtime.low: 120

battery.voltage: 27.60

battery.voltage.nominal: 024

driver.name: apcsmart

driver.parameter.port: /dev/ttyS0

driver.version: 2.0.4

driver.version.internal: 1.99.8

input.frequency: 60.00

input.quality: FF

input.sensitivity: H

input.transfer.high: 132

input.transfer.low: 103

input.transfer.reason: S

input.voltage: 120.2

input.voltage.maximum: 121.5

input.voltage.minimum: 119.6

output.voltage: 120.2

output.voltage.target.battery: 115

ups.delay.shutdown: 180

ups.delay.start: 000

ups.firmware: 50.14.D

ups.id: UPS_IDEN

ups.load: 008.3

ups.mfr: APC

ups.mfr.date: 08/02/03

ups.model: SMART-UPS 700

ups.serial: QS0331213446

ups.status: OL

ups.temperature: 037.8

ups.test.interval: 1209600

ups.test.result: NO

Testing power loss is accomplished with the upsdrvctl utility. The value of ups.delay.shutdown is the amount of time in seconds the UPS will wait before shutting down. In the above listing the value is 180 seconds. This value can be changed with the upsrw utility, though a valid user in upsd.users with proper permissions must be defined to change variable values. Refer to the upsd.users andupsrw man pages for more information. The 180 second delay is enough time to allow for a proper shut down of this system.

# upsdrvctl shutdown labsvr; shutdown -h +0

After this command is run, upsdrvctl tells the UPS to issue its shutdown sequence. The second command tells the system to shutdown immediately. The server shuts down and after the 180 second delay the UPS shuts down and powers back up. If the BIOS is set correctly in the server, when the UPS supplies line power again the server system comes back on line.

In addition to the extensive documentation installed in/usr/share/doc/nut/ and on the NUT web site, the man pages contain excellent detailed information on the utilities, configuration files and drivers.

Conclusion

Power interruptions are a common problem in many areas and can cause eventual failure of components and systems. Having an uninterruptible power supply to prevent damage and initiate proper power down sequences can save many headaches as well as avoid disaster. Just implementing a UPS system is not enough and the proper UPS, server cabling and motherboard BIOS are all part of a reliable system.

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How To Manage Your Uninterruptible Power Supply With UPS Assistant

noreply@blogger.com (ADMIN) — Mon, 03 Oct 2011 14:04:00 +0000

UPS Assistant is a free utility that monitors the status of your Uninterruptible Power Supply(UPS) connected to a computer through USB-port and supporting the Megatec/Centralion protocol (Ippon, Mustek, Sven, Inelt). You can also find out more information about your UPS such as status, data stream, battery level, etc.

You can enter your email to get notified about warnings and customize everything manually. You can see the full details about your battery and know how much more time is left before your battery becomes dead. It supports HTTP server to receive reports via the Web with possibility of user authentication.

It has been tested with Windows 7 Beta Build 7000 x64, so it should work great on official Windows 7 Beta too.

This tool keeps a log of all activity and alerts you if something goes wrong. Overall using this feature rich utility is a great way to manage your Uninterruptible Power Supply when connected via USB port.

Click her to download the last version of USP Assistant.

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How to Build Your Own Uninterruptible Power Supply

noreply@blogger.com (ADMIN) — Mon, 03 Oct 2011 13:39:00 +0000

In the event of extended blackout, you may have critical systems (such as computer or medical equipment) that must remain running no matter what. This guide will yield one scalable uninterrupted power supply system. You may extend it with power generation, or solar/wind/etc. as you see fit.

Most uninterrupted power supplies sold for computers 'switch' power, running a small inverter when power is interrupted, then switching back to 'normal' power when it's back on. This one simply produces AC power with a continuous duty inverter and assumes some system(s) will charge the DC battery supply it requires faster than it consumes it. This makes the design simpler and also allows more than one kind of DC power source to participate in charging the batteries. Your UPS system here will be an online type.

Steps

1- Read all warnings before proceeding. This is for your safety.

2-Choose a charger that can supply enough current to charge the battery and keep up with the inverter's load. This will be a fairly heavy duty charger.

· Check RV suppliers for 'Converters', designed to run larger RVs if you are making a big system.

· Check solar power sources for "big" whole house chargers and inverters for very large systems.

· If an RV or home converter has an inverter built in, make sure it's isolated (or can be isolated) from the input power.

· Make sure the charger handles the kinds of batteries you are going to buy.

3-Choose only deep cycle batteries. Do not use a car or truck battery, nor a 'marine' battery. If you will be using only one battery, a gel or 'maintenance free' battery will work adequately. For larger systems composed of multiple deep-cycle batteries, select only wet cells or AGM cells.

· Make sure the batteries are ventilated for escaping hydrogen gas.

· If you buy wet cells, make sure the charger supports an 'equalize' charge.

· Lead acid batteries are sold in 6 volt and 12 volt sizes. You will need to connect them in series to raise the voltage, or in parallel to increase the amp-hours available.

o 12 volts = 2x6V volt batteries connected in series

o 24 volts = 4x6V or 2x12V batteries in series

o When connecting series-parallel, connect pairs of batteries in parallel and then connect those pairs in series, not chains of series batteries in parallel.

· Do not mix different kinds of batteries. Newer batteries added to existing sets of batteries will be as worn as the originals very quickly.

· In larger series-parallel setups it's a good idea to swap batteries around every year or so.

· Batteries that are shallowly drained (cycled) will last a long time, while batteries that are deeply cycled will have shorter lives.

· A fully charged, new 12 volt battery is 12.6 volts at rest (each of six cells is 2.1 volts).

· A fully charged, new 6 volt battery will be at 6.3 volts at rest.

· When a 12 volt charger is operating on it, the voltage will be higher. A float charge (maintenance charge) for a 12 volt system is 13.5 to 13.8 volts; active charging requires at least 14.1 volts. You may see it go as high as 16 volts when charging, depending upon the charger. After a full charge, if the battery is not going to be float charged, the at-rest voltage will slowly return to the nominal full-charge voltage.

· A discharged 12 volt battery is 11.6 volts at rest. A discharged 6 volt battery is 5.8 volts at rest. The voltage may temporarily fall below these levels while powering a large load, but should return to a point within the nominal range after a 1-hour rest. Over-discharging to less than 1.93 volts per cell at rest will permanently damage your battery.

· Batteries can be measured with a voltmeter for an approximate state of charge, but many dead batteries can hold a 'shallow charge' which drops off rapidly when current is drawn. You'll need to test them with a 'live' load over a series of hours to verify them.

· A regulated 12 volt power supply can not fully charge a discharged 12 volt battery, but it makes a good float charger if the output voltage is correct (again, 13.5-13.8 volts for a 12 volt system). Check the water level in the cells often, and replenish as needed with distilled water.

4-Choose an inverter.

· Rated for continuous duty at substantially more power than you think you'll need.

· Enough 'peak' current to handle motor starting loads, which can be from 3 to as much as 7 times the rated running wattage.

· Inverters are available for input voltages of 12, 24, 36, 48, and 96 volts, and a few less common voltages. The higher the voltage the better, especially for large systems. 12 volts is the most common, but in no case should one consider 12 volts for a system of greater than 2400 watts output (The amount of current that has to be handled is simply too high).

· Some of the better inverters have a built-in 3-stage automatic battery charger and transfer relay, greatly simplifying the system. These inverters are well worth the extra money; if fact they save money overall, as the built-in charger is a bargain compared to the price of a comparable stand-alone charger.

5-Get cables and fuses and other hardware to interconnect batteries, charger and inverter.

· These should be very heavy gauge, well made, and as short as you can fit it all together with. This is to keep the cable resistance low.

· Consider spending just a bit more for a bus bar interconnect with big dividers, instead of just 'wires everywhere'. It is tidy and helps prevent accidental shorts. It also makes it easier to remove defective batteries.

6-Wear protective gear and observe safety precautions.

· Don your eye protection to protect against acid splashes to the eye.

· Wear protective, non-conductive gloves if possible.

· Remove any jewelry and any metallic items you might be wearing.

7-Securely attach the charger cables to the deep cycle battery, noting polarity.

8-Prepare the charging system. Plug the charger into the wall and power it on. Make sure it begins a proper charge cycle, and make sure the inverter is powered off.

9-Attach and test the inverter if it is separate from the charger. Hook up the cables to the batteries, noting polarity. Turn the inverter on and test it with some suitable AC load. You shouldn't see sparks, smoke, or fire at any point. Leave the inverter on with a load similar to your planned load and allow the battery to charge overnight. This will test that the charger and load are a good match. In the morning, the battery should be fully charged.

10-Dismantle the test rig.

11-Design a tidy enclosure. This could be shelves in a shed, or a very large container. This will hold the batteries, charger, and inverter. Generally the charger and inverter should not be right next to the batteries where escaping gas can get to them. If so, it can shorten the life of the electronics, or ignite gases from sparking if vents are blocked. Some partition should be installed and separate air circulation should be provided for the charger and inverter. Alternatively, mount the charger/inverter outside the battery box. Once ready, install the components into it.

12-Make the connections. Runs of cable should be kept fairly short. You need easy access to every battery to check, so clean and tighten cables. For wet cells, you need to be able to easily take every top off to check fluid levels and get distilled water into them. Make sure the inverter is grounded. You may ground it to the ground wire on the charger's input AC, or use a grounding rod driven into the soil.

13-Supplement alternatives where beneficial or necessary. You may supplement or replace the charger with solar, wind, etc., connected to their own applicable charge controller. This can keep the power running far longer than it otherwise would, even indefinitely. Also, you may supplement the charger with a generator. Attach a truck alternator to a small internal combustion engine, use a generator with 12 volt charging output, or unplug the charger from its AC outlet and then use a 'regular' AC generator to power the charger.

Tips

· Do not plug surge suppressors into the inverter. It is isolated from the grid and outside.

· The UPS can be located outside.

o Install an inside and outside outlet through a wall connected only to each other. You can plug the UPS inverter into the outside outlet (with a 'gender bender' extension cable) to power the inside outlet.

o Disconnect and isolate an indoor circuit from the main circuit breaker panel. Route the wire out of that box through one of the punch-outs or remove it, and connect it to the inverter, providing conduit to shield as applicable. All plugs/lights/smoke detectors/etc. on that circuit will be powered by the UPS, so test and make sure nothing 'extra' is connected to it.

o Run conduit and/or get fancy as you see fit, relative the permanence of your solution.

Warnings

· If you're not a very safe electrician, don't try any of this.

· Grounding the inverter is not optional, it is a must. Remember to obey local regulations regarding grounding, especially if only one grounding rod is allowed per site.

· If power goes to outside outlets or near water, either buy an inverter with a Ground Fault Interrupt and ground it, or add a GFI to it.

· The AC output from the inverter is almost similar to mains power and can kill you.

· The DC current from the battery can burn you. A ring that gets between 'hot' wires can amputate your finger.

· There is enough DC current in a battery bank to stop your heart.

· Do not wear watches or jewelry when working on the batteries.

· Wear eye protection when working on batteries.

· Shorting batteries can cause blinding flashes, blow wrenches into splinters, even cause the batteries to explode and spray sulphuric acid and hunks of plastic everywhere.

· Provide proper ventilation for batteries. Trapped hydrogen gas can ignite and/or explode.

· Don't mess with the circuit breaker panel if you're not a really very good (and very, very safe) electrician.

· Wearing shoes is recommended.

Things You'll Need

· One or more deep cycle batteries

· One battery charger (at the voltage of the battery bank, and matching battery chemistry)

· One heavy duty inverter

· Battery cables

· Eye, face, and hand protection (for handling batteries)

Source: http://www.wikihow.com

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Back-feed Protection in Uninterruptible Power Supplies

noreply@blogger.com (ADMIN) — Wed, 28 Sep 2011 11:25:00 +0000

Back-feed protection, in uninterruptible power supplies (UPS), prevents the risk of electric shock from any electric current feeding back from the UPS output in the event of a mains supply failure. When mains fails and connected loads are protected by uninterruptible power supplies, a back-feed protection device prevents current from being passed back to the input terminals of the UPS from the inverter output. This is extremely important for health and safety reasons because it enables a service engineer to work on the incoming supply side of the UPS without risk of receiving an electric shock.

A example of what could happen, in the event of a mains power failure, is that a bypass supply thyristor, which has short-circuited causing the output from the inverter to be passed through to the input terminals via the faulty component. It is something that must be prevented at all costs – not only to safeguard engineers but uninterruptible power supply protected loads too. Even when the input supply has been switched off, via an isolator, there is potential for it to happen, hence the need for back-feed protection. The type of back-feed device employed is determined by the size of the uninterruptible power supply.

Plug-in Uninterruptible Power Supplies

Back-feed protection for a single-phase uninterruptible power supply, up to 16A, needs to provide protection for both live and neutral input conductors using a specified air gap. The air gap is usually provided by means of a relay that opens when mains power supply fails.

For plug-in uninterruptible power supplies, if a fault occurs when the user disconnects it from the mains power supply (by simply unplugging it from the wall socket), the back-feed relay should prevent the exposed pins from becoming live. It should also remove any possibility of the user receiving an electric shock.

UPS systems over 16A are hardwired (normally) and utilise one of two different approaches: mechanical or electronic.

Hardwired Uninterruptible Power Supply

Mechanical Back-feed Device:

Some hardwired uninterruptible power supplies are provided with the relay or contactor-based solution as used in 16A plug-in models. This, again, provides a specified safety air gap which opens when the mains power supply is disconnected or fails. Only the phase conductors are disconnected and the neutral always remains connected.

Electronic Back-feed Device:

Many hardwired uninterruptible power supplies utilise a back-feed current detection system, which continually monitors the current flow through the bypass supply. Should a fault occur within the bypass thyristors, it is detected by the UPS, which then immediately shuts down its inverter.

Back-feed protection is so simple to implement but is often overlooked. As with many potential hazards associated with electrical circuitry, such a simple problems can often, if not addressed, lead to a very complicated and costly set of circumstances. Static switches are part of online UPS design. Chances are back-feed protection will have been incorporated into the uninterruptible power supply units at the manufacturing stage but it is always best to check.

Source: http://www.articlesbase.com/

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Comparing Transformer-based and Transformerless Uninterruptible Power Supplies

noreply@blogger.com (ADMIN) — Wed, 28 Sep 2011 10:38:00 +0000

Choosing between transformer-based or transformerless uninterruptible power supplies may not be a simple ‘either/or’ decision, particularly above 10kVA. Both technologies have their place in today’s power protection scenarios but the key differences between them are: physical size, efficiency, noise output and the levels of input harmonic distortion that they generate.

Both uninterruptible power supply designs produce a tightly regulated source of uninterrupted power but they differ in the way they generate the dc voltage required by their inverters and their output stages.

Transformer-based Uninterruptible Power Supplies:

until the early 1990s, the only design of online uninterruptible power supply was transformer-based. Nowadays, the design is still available but generally in larger sizes for UPS from eight to 800kVA. The most common applications for this are large industrial sites.

This type of UPS has a robust transformer-isolated inverter output, which makes it more suitable for the type of application where there is a likelihood of electrical noise; spikes, transients, and potentially, a high degree of short-circuit currents.

The inverter generates an ac supply from its dc power source, which is fed into a step-up transformer. The primary function of the transformer is to increase the inverter ac voltage to that required by the load. The transformer also protects the inverter from load disruption, whilst also providing Galvanic isolation (a method of isolating input and output).

Modern inverter designs use IGBTs (Insulated Gate Bipolar Transistors) in place of more traditional switching components (such as power transistors and thyristors). IGBTs combine the fast-acting and high power capability of the Bipolar Transistor with the voltage control features of a MOSFET gate to form a versatile, high frequency switching device. This in turn has given rise to more powerful, efficient and reliable inverters.

Transformer-based UPS are also supplied with a dual input option as standard, which can be selected at installation by simply removing a linking connector from its input terminal. This allows it to be powered from two separate ac supply sources thus adding further resilience. A transformerless UPS can be installed with dual input capability, with supplies derived from the same source, but this is typically a factory-fit option.

Transformerless Uninterruptible Power Systems:

Transformerless UPS is a newer design, commonly available from 700VA to 120kVA. The primary purpose behind the introduction of transformerless units was to reduce the overall physical size and weight thus making an uninterruptible power supply unit more suitable for smaller installations and/or computer room/office type environments, where space may be limited. It also generates far less noise and heat than its transformer-based cousin and has far lower input harmonic distortion levels making it compatible with environments where electronic equipment (such as computers) may be more sensitive to this type of distortion.

In place of the step-up transformer, a transformerless UPS uses a staged process of voltage conversion. The first stage combines a rectifier and booster-converter to generate a dc supply for the inverter. An uncontrolled, three-phase bridge rectifier converts the ac supply into a dc voltage. This is passed through a mid-point booster circuit to step the dc voltage up to typically 700-800Vdc from which a battery charger and inverter are powered. In the second stage, the inverter takes the supply from the booster-converter and inverts it back to an ac voltage to supply the load.

An added benefit of this method is that the rectifier can operate from either a three or single-phase input supply. This can be configured at installation for systems up to 20kVA. A control system ensures a stable, regulated dc voltage is supplied to the inverter at all times and the inverter can operate regardless of UPS output load variations or mains power supply fluctuations or disturbances.

Choosing between Transformer-based or Transformerless Uninterruptible Power Supplies:

In many applications the choice between the two may be clear. It is where the two ranges overlap, in terms of power rating, that the decision is more complicated. Consideration needs to be given then to: initial purchase cost, physical size, running costs, the installation environment, and in particular, the levels of input harmonic distortion they generate. Both designs can be operated in parallel to achieve higher levels of availability and resilience.

Over the last decade, the gap between these two uninterruptible power supply technologies has reduced as manufacturers have applied common techniques and research & development efforts to both designs. The driving force behind this has been cost and size, alongside demands to improve operating efficiency and reduce harmonic generation. In terms of online performance, both designs provide the same level of performance and are classified as VFI systems (voltage and frequency independent - in accordance with EN/IEC 62040-3). Their principal differences are their effects on upstream supplies and the operating environment.

Transformerless UPS are generally recognised as more efficient and having a higher power factor than an equivalent transformer-based design, therefore operating costs can be lower.

Below 10kVA, the transformerless UPS design dominates the online uninterruptible power supply market and has become the standard within data centre environments as they offer a more compact footprint, higher operating efficiencies and lower noise output. However, the strengths of the transformer-based design come into play in the industrial environment.

Source: http://www.articlesbase.com

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Industrial Uninterruptible Power Supply Overview

noreply@blogger.com (ADMIN) — Wed, 28 Sep 2011 09:12:00 +0000

In last years industrial uninterruptible power supply is becoming very important part of infrastructures and industries where they can't afford lack of power. So it's accustomed to help protect from power electricity lost in places for example data centers, telecommunication facilities, places with computer servers, hospitals, factories, supermarket, airports, basically it can be found anywhere. Industrial uninterruptible power supply is generally utilized in conjunction with diesel generators. Where ups can be used in first minutes of power failure. Which is simply enough time for heavy duty diesel generators to begin. After diesel is fully running it requires over the load. Generator is usually configured with delay when switching back loads to ups, just in case you will find shorter interruptions.

Power ranges of Industrial uninterruptible power supply are from very small 300 - 800 VA (used mostly for private computers) as much as high-powered industrial Uninterruptible power supply which may be up to 1000kVA.

Of course it always possible to place more devices into parallel, thus which makes them even stronger. They upper dimensions are limited by technology, mostly by peak current through thyristors. Thyristors and capacitors represent also the costliest part (besides batteries) of ups.

Online double conversion uninterruptible power supply would be the most used ups devices. It has pure sine wave that is actually better sine wave then delivered through power distribution. Because of this in case of power outage the transfer of load is without interruption from normal mode to battery mode. The power efficiency can be between 92 to 97% and of course smaller if compared to offline or line interactive ups, but when working with expensive and sensitive loads its absolutely essential to protect them not just from power outage but additionally from al kind of noises and spike that may come through mains power supply distribution.

Offline ups are kind of cheaper variant, it cheap to made, and when in normal mode it uses almost no power, that's why it have very high power efficiency (or own consumption). But it doesn't protect ups from noises or smaller changes in main voltages. Also the transfer time from normal mode to batter mode would be to big for sensitive electronic components. Line interactive ups on contrary is something between online and offline ups. because it has transformer its resilient to alterations in output voltage, but still it doesn't full protect loads like online uninterruptible power supply does.

Typical autonomy battery time is usually from 8-15 minutes, however in any ups over 1 kVA that may be usually increases by adding more batteries, modules or even more battery cabinets. Generally batteries are 12 V or 6 V. So 3 or 6 cell batteries, where each cell is 2 V. Battery capacity is from 5 Ah to over 100 Ah. Batteries used should be deep cycle batteries. Normal batteries last from three to 5 years, while longevity batteries could last up to Ten years. Will depend on environment which should be too hot. It should between 15 to 22 degrees Celsius.

Uninterruptible power supply might have 1 phase or 3 phase input, same goes for output. Larger ups devices usually have communication card, so its possible to monitor device over lan or over internet. It's also possible to configure remote shutdowns. So for example if ups can be used in data center its likely to configure loads - computers to shut down when time on battery reaches some critical value.

Typical components of industrial uninterruptible power supply are rectifier, inverter, batteries and wall charger. Rectifier transform ac mains to dc power, inverter convert this dc power back to ac power, although it can also convert dc battery power to ac power. Of course for converting low voltage battery power there's a part called booster that boost voltage to raised value that is more desirable for transforming from dc to ac. Important parts are also electronic bypass and manual bypass. When there are overload ups will switch to electronic bypass because of its protection. Loads will not be disturbed in this instance. Manual bypass can be used for maintenance purposes in last case obviously loads aren't protected anymore.

In cases where there is needed ultra stability more industrial uninterruptible power supply can be used into parallel for bigger security or just to increase overall power.

The most known industrial uninterruptible power supply brands are Apc, Socomec, Eaton, Cyber power, Liebert and GE Digital energy

Source: http://www.articlesbase.com

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Uninterruptible Power Supplies Uk: Backbone of Life

noreply@blogger.com (ADMIN) — Wed, 28 Sep 2011 08:40:00 +0000

Life runs on electricity. The more developed country the more it runs on electricity. Power cuts can simply leave you paralyzed at times. The power trips and sheddings are unavoidable but UPS and generators act as major power backups at these faulty times. Uninterruptible Power Supplies or (UPS) as it is more popularly called is very useful both in domestic and industrial purposes.

The Uninterruptible Power Supplies in UK are the major reliability factor in case of power trips and cuts in the country. In the UK you can see Uninterruptible Power Supplies just everywhere starting from homes to offices to industrial plants to hospitals. The Uninterruptible Power Supplies used in the UK range from 200VA to 4.8mVA. They are often backup with generators but according to requirements.

More about Uninterruptible Power Supplies of the UK

Uninterruptible Power Supplies have a battery pack and an input and output phase. The battery forms DC and gets converted to AC when entering the appliance, through which the appliance works.

The Uninterruptible Power Supplies can run more than one device at a time and a variety of devices. But then you have to choose the Uninterruptible Power Supplies or (UPS) according to the output watt you need. There is one or more output phase in the UPS through which you can connect your devices.

Working of the Uninterruptible Power Supplies

There are two modes of working of the Uninterruptible Power Supplies.

One is Offline Working.

In it the Uninterruptible Power Supplies is connected to the device and once the UPS detects power trip from the main current supply it gets started immediately. Here the device gets off if there is no automatic start mode. Being comparatively cheap it is more preferable at homes. But when you are to install the Uninterruptible Power Supplies in places where a momentary power cut off can lead to disasters like in IT companies.

You should go in for the Online Uninterruptible Power Supplies where the UPS is connected directly to the circuit of the device. Here the UPS runs continuously but only when the current is off. The current is produced by the battery and in the case of presence of supply of power; the battery keeps on charging automatically. This is best applicable when you need complete power supply for the appliances.

Source: http://www.articlesbase.com/

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Benefits of using uninterrupted power supply

noreply@blogger.com (ADMIN) — Wed, 28 Sep 2011 08:04:00 +0000

In many organization whether its small or large organization, they use Uninterrupted Power Supply (UPS) to protect their systems. Not only the systems it could be anything like machinery, refrigerators, servers, computers or any other electronic gadgets to protect their work from the loss of the data in the event of a power failure. Because they work continuously and they do not shut any of their machines for a single minute, if they do they have to suffer a huge loss so for this reason they use battery.

Battery comes into different sizes and the units and as per the use or the need of the batteries. batteries work same as generator but they are better than the generators. They continuous supply power to your systems in case of power failure. Generator may cause your systems but there is no chance you lose your data in uninterrupted power supply.

There are many companies who manufacturers UPS like HP, Dell, Shenzhen Santakups Electronic, cyber Power systems, APC, etc. And it comes into variety of ranges, previously UPS were very expensive.

Each UPS has been developed by the company comes into different units, prices and so on. These companies understand the actual need of the UPS. In today’s globalised world, each and every organization works with computers, uses computers. No organization is maintaining books for any records; it is time consuming as well as expensive and it saves lots of time of the company. So, every company whether it is small or large use software for maintaining records. Whether it’s a business centers, data centers, servers or the manufacturing processes they demand power which can be supplied by installing high units of Uninterrupted Power Supply.

Now a day’s the Online Uninterrupted Power Supply is considered to be the most expensive and advanced form. No doubt they are noisy, contain cooling fans and require some planning if you want to establish in small office or at home. The main benefit of the Uninterrupted Power Supply is when there is a power cut; UPS switch to its battery and start loading whereas generator takes some time to load. When there is bad power supply, UPS decides that the power is bad and its load remains on the batteries. UPS either switched to the main input or simply dies depending upon the UPS design, units and upon the company.

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Battery Backup Using UPS

noreply@blogger.com (ADMIN) — Tue, 27 Sep 2011 12:54:00 +0000

What is a Battery Backup?:

A battery backup, or uninterruptible power supply (UPS), is primarily used to provide a backup power source to the parts in the computer case, the monitor, and any other device plugged in to the battery backup.

A Battery Backup is Also Known As:

UPS, uninterruptible power supply, uninterruptible power source

Important Battery Backup Facts:

In addition to acting as a backup when the power goes out, most battery backup devices also act as power "conditioners" by ensuring that the electricity flowing to your computer and accessories is free from drops or surges. If a computer is not receiving a consistent flow of electricity, damage can and often does occur.

While a UPS system is not a required pieces of a complete computer system, including one as part of yours is always recommended. The need for a reliable supply of electricity is often overlooked.

Popular Battery Backup Manufacturers:

APC, Belkin, CyberPower, Tripp Lite, Ultra

Battery Backup Description:

The battery backup sits between the utility power (power from the wall outlet) and the parts of the computer. In other words, the computer and accessories plug into the battery backup and the battery backup plugs into the wall.

UPS devices come in many shapes and sizes but are most commonly rectangular and free standing, intended to sit on the floor near the computer. All battery backups are very heavy due to the batteries located inside the device.

One or more batteries inside the UPS provide power to the devices plugged into it when power from the wall outlet is no longer available. The batteries are rechargeable and often replaceable, providing a long term solution to keeping your computer system running.

The front of the battery backup will usually have a power switch to turn the device on and off and will also sometimes have one or more additional buttons that perform various functions. Higher-end battery backup units will also often feature LCD screens that show information about how charged the batteries are, how much power is being used, etc.

The rear of the UPS will feature one or more outlets that provide battery backup. In addition, many battery backup devices will also feature surge protection on additional outlets and sometimes even protection for network connections, as well as phone and cable lines.

Battery backup devices are manufactured with varying degrees of backup ability. To determine how powerful of a UPS you need, first use the Journey Systems Power Supply Calculator to calculate your computer's wattage requirements. Take this number and add it to the wattage requirements for other devices you would plug into the battery backup. Take this totaled number and check with the UPS manufacturer to find your estimated battery runtime when you lose power from the wall.

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Uninterruptible power supply (UPS)

noreply@blogger.com (ADMIN) — Tue, 27 Sep 2011 11:20:00 +0000

An uninterruptible power supply, also uninterruptible power source, UPS or battery/flywheel backup, is an electrical apparatus that provides emergency power to a load when the input power source, typically mains power, fails. A UPS differs from an auxiliary or emergency power system or standby generator in that it will provide instantaneous or near-instantaneous protection from input power interruptions by means of one or more attached batteries and associated electronic circuitry for low power users, and or by means of diesel generators and flywheels for high power users. The on-battery runtime of most uninterruptible power sources is relatively short—5–15 minutes being typical for smaller units—but sufficient to allow time to bring an auxiliary power source on line, or to properly shut down the protected equipment.

While not limited to protecting any particular type of equipment, a UPS is typically used to protect computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS units range in size from units designed to protect a single computer without a video monitor (around 200 VA rating) to large units powering entire data centers, buildings, or even cities.

Common Power Problems

The primary role of any UPS is to provide short-term power when the input power source fails. However, most UPS units are also capable in varying degrees of correcting common utility power problems:

1. Power failure: defined as a total loss of input voltage.

2. Surge: defined as a momentary or sustained increase in the main voltage.

3. Sag: defined as a momentary or sustained reduction in input voltage.

4. Spikes, defined as a brief high voltage excursion.

5. Noise, defined as a high frequency transient or oscillation, usually injected into the line by nearby equipment.

6. Frequency instability: defined as temporary changes in the mains frequency.

7. Harmonic distortion: defined as a departure from the ideal sinusoidal waveform expected on the line.

UPS units are divided into categories based on which of the above problems they address, and some manufacturers categorize their products in accordance with the number of power-related problems they address.

Technologies

The general categories of modern UPS systems are on-line, line-interactive or standby.^[3] An on-line UPS uses a "double conversion" method of accepting AC input, rectifying to DC for passing through the rechargeable battery (or battery strings), then inverting back to 120 V/230 V AC for powering the protected equipment. A line-interactive UPS maintains the inverter in line and redirects the battery's DC current path from the normal charging mode to supplying current when power is lost. In a standby ("off-line") system the load is powered directly by the input power and the backup power circuitry is only invoked when the utility power fails. Most UPS below 1 kVA are of the line-interactive or standby variety which are usually less expensive.

For large power units, dynamic uninterruptible power supplies are sometimes used. A synchronous motor/alternator is connected on the mains via a choke. Energy is stored in a flywheel. When the mains power fails, an Eddy-current regulation maintains the power on the load. DUPS are sometimes combined or integrated with a diesel generator, forming a diesel rotary uninterruptible power supply(DRUPS).

A fuel cell UPS has been developed in recent years using hydrogen and a fuel cell as a power source, potentially providing long run times in a small space.

Offline/Standby

The offline / standby UPS (SPS) offers only the most basic features, providing surge protection and battery backup. The protected equipment is normally connected directly to incoming utility power. When the incoming voltage falls below a predetermined level the SPS turns on its internal DC-AC inverter circuitry, which is powered from an internal storage battery. The SPS then mechanically switches the connected equipment on to its DC-AC inverter output. The switchover time can be as long as 25 milliseconds depending on the amount of time it takes the standby UPS to detect the lost utility voltage. The UPS will be designed to power certain equipment, such as a personal computer, without any objectionable dip or brownout to that device.

Line-interactive

The line-interactive UPS is similar in operation to a standby UPS, but with the addition of a multi-tap variable-voltage autotransformer. This is a special type of transformer that can add or subtract powered coils of wire, thereby increasing or decreasing the magnetic field and the output voltage of the transformer.

This type of UPS is able to tolerate continuous undervoltage brownouts and overvoltage surges without consuming the limited reserve battery power. It instead compensates by automatically selecting different power taps on the autotransformer. Depending on the design, changing the autotransformer tap can cause a very brief output power disruption,^[4] which may cause UPSs equipped with a power-loss alarm to "chirp" for a moment.

This has become popular even in the cheapest UPSs because it takes advantage of components already included. The main 50/60 Hz transformer used to convert between line voltage and battery voltage needs to provide two slightly different turns ratios: one to convert the battery output voltage (typically a multiple of 12 V) to line voltage, and a second one to convert the line voltage to a slightly higher battery charging voltage (such as a multiple of 14 V). Further, it is easier to do the switching on the line-voltage side of the transformer because of the lower currents on that side.

To gain the buck/boost feature, all that is required is two separate switches so that the AC input can be connected to one of the two primary taps, while the load is connected to the other, thus using the main transformer's primary windings as an autotransformer. The battery can still be charged while "bucking" an overvoltage, but while "boosting" an undervoltage, the transformer output is too low to charge the batteries.

Autotransformers can be engineered to cover a wide range of varying input voltages, but this requires more taps and increases complexity, and expense of the UPS. It is common for the autotransformer to cover a range only from about 90 V to 140 V for 120 V power, and then switch to battery if the voltage goes much higher or lower than that range.

In low-voltage conditions the UPS will use more current than normal so it may need a higher current circuit than a normal device. For example to power a 1000-watt device at 120 volts, the UPS will draw 8.32 amperes. If a brownout occurs and the voltage drops to 100 volts, the UPS will draw 10 amperes to compensate. This also works in reverse, so that in an overvoltage condition, the UPS will need less current.

Double-conversion / online

The online UPS is ideal for environments where electrical isolation is necessary or for equipment that is very sensitive to power fluctuations. Although once previously reserved for very large installations of 10 kW or more, advances in technology have now permitted it to be available as a common consumer device, supplying 500 watts or less. The initial cost of the online UPS may be slightly higher, but its total cost of ownership is generally lower due to longer battery life. The online UPS may be necessary when the power environment is "noisy", when utility power sags, outages and other anomalies are frequent, when protection of sensitive IT equipment loads is required, or when operation from an extended-run backup generator is necessary.

The basic technology of the online UPS is the same as in a standby or line-interactive UPS. However it typically costs much more, due to it having a much greater current AC-to-DC battery-charger/rectifier, and with the rectifier and inverter designed to run continuously with improved cooling systems. It is called a double-conversion UPS due to the rectifier directly driving the inverter, even when powered from normal AC current.

In an online UPS, the batteries are always connected to the inverter, so that no power transfer switches are necessary. When power loss occurs, the rectifier simply drops out of the circuit and the batteries keep the power steady and unchanged. When power is restored, the rectifier resumes carrying most of the load and begins charging the batteries, though the charging current may be limited to prevent the high-power rectifier from overheating the batteries and boiling off the electrolyte.

The main advantage to the on-line UPS is its ability to provide an electrical firewall between the incoming utility power and sensitive electronic equipment. While the standby and line-interactive UPS merely filter the input utility power, the double-conversion UPS provides a layer of insulation from power quality problems. It allows control of output voltage and frequency regardless of input voltage and frequency.

Hybrid topology / double conversion on demand

These hybrid designs do not have an official designation, although one name used by HP and Eaton is double conversion on demand.^[5] This style of UPS is targeted towards high efficiency applications while still maintaining the features and protection level offered by double conversion.

A hybrid (double conversion on demand) UPS operates as an off-line/standby UPS when power conditions are within a certain preset window. This allows the UPS to achieve very high efficiency ratings. When the power conditions fluctuate outside of the predefined windows, the UPS switches to online/double conversion operation.^[5] In double conversion mode the UPS can adjust for voltage variations without having to use battery power, can filter out line noise and control frequency. Examples of this hybrid/double conversion on demand UPS design are the HP R8000, HP R12000, HP RP12000/3 and the Eaton BladeUPS.

Ferro-resonant

Ferro-resonant units operate in the same way as a standby UPS unit; however, they are online with the exception that a ferro-resonant transformer is used to filter the output. This transformer is designed to hold energy long enough to cover the time between switching from line power to battery power and effectively eliminates the transfer time. Many ferro-resonant UPSs are 82–88% efficient (AC/DC-AC) and offer excellent isolation.

The transformer has three windings, one for ordinary mains power, the second for rectified battery power, and the third for output AC power to the load.

This once was the dominant type of UPS and is limited to around the 150 kVA range. These units are still mainly used in some industrial settings (oil and gas, petrochemical, chemical, utility, and heavy industry markets) due to the robust nature of the UPS. Many ferro-resonant UPSs utilizing controlled ferro technology may not interact with power-factor-correcting equipment.

DC power

A UPS designed for powering DC equipment is very similar to an online UPS, except that it does not need an output inverter, and often the powered device does not need a power supply. Rather than converting AC to DC to charge batteries, then DC to AC to power the external device, and then back to DC inside the powered device, some equipment accepts DC power directly and allows one or more conversion steps to be eliminated. This equipment is more commonly known as a rectifier.

Many systems used in telecommunications use 48 V DC power, because it is not considered a high-voltage by most electrical codes and is exempt from many safety regulations, such as being installed in conduit and junction boxes. DC has typically been the dominant power source for telecommunications, and AC has typically been the dominant source for computers and servers.

There has been much experimentation with 48 V DC power for computer servers, in the hope of reducing the likelihood of failure and the cost of equipment. However, to supply the same amount of power, the current must be greater than an equivalent 120 V or 230 V circuit, and greater current requires larger conductors and/or more energy to be lost as heat.

High voltage DC (380 V) is finding use in some data center applications, and allows for small power conductors, but is subject to the more complex electrical code rules for safe containment of high voltages.^[6]

Most switched-mode power supply (SMPS) power supplies for PCs can handle 325 V DC (230 V mains voltage × √2) directly, because the first thing they do to the AC input is rectify it. This does cause unbalanced heating in the input rectifier stage as the full load passes through only half of it, but that is not generally a significant problem. (Power supplies with a 115/230 V switch operate as a voltage doubler when in the 115 V position, which does require AC power, but the voltage doubler configuration also uses only half the rectifier, so it is certain to be able to handle the unbalance when operated from DC in the 230 V position.)

Rotary DRUPS (diesel rotary UPS)

A rotary UPS uses the inertia of a high-mass spinning flywheel (flywheel energy storage) to provide short-term ride-through in the event of power loss. The flywheel also acts as a buffer against power spikes and sags, since such short-term power events are not able to appreciably affect the rotational speed of the high-mass flywheel. It is also one of the oldest designs, predating vacuum tubes and integrated circuits.

It can be considered to be on line since it spins continuously under normal conditions. However, unlike a battery-based UPS, flywheel-based UPS systems typically provide 10 to 20 seconds of protection before the flywheel has slowed and power output stops. It is traditionally used in conjunction with standby diesel generators, providing backup power only for the brief period of time the engine needs to start running and stabilize its output.

The rotary UPS is generally reserved for applications needing more than 10,000 watts of protection, to justify the expense and benefit from the advantages rotary UPS systems bring. A larger flywheel or multiple flywheels operating in parallel will increase the reserve running time or capacity.

Because the flywheels are a mechanical power source, it is not necessary to use an electric motor or generator as an intermediary between it and a diesel engine designed to provide emergency power. By using a transmission gearbox, the rotational inertia of the flywheel can be used to directly start up a diesel engine, and once running, the diesel engine can be used to directly spin the flywheel. Multiple flywheels can likewise be connected in parallel through mechanical countershafts, without the need for separate motors and generators for each flywheel.

They are normally designed to provide very high current output compared to a purely electronic UPS, and are better able to provide inrush current for inductive loads such as motor startup or compressor loads, as well as medical MRI and cath lab equipment. It is also able to tolerate short-circuit conditions up to 17 times larger than an electronic UPS, permitting one device to blow a fuse and fail while other devices still continue to be powered from the rotary UPS.

Its life cycle is usually far greater than a purely electronic UPS, up to 30 years or more. But they do require periodic downtime for mechanical maintenance, such as ball bearing replacement. In larger systems redundancy of the system ensures the availability of processes during this maintenance. Battery-based designs do not require downtime if the batteries can be hot-swapped, which is usually the case for larger units. Newer rotary units use technologies such as magnetic bearings and air-evacuated enclosures to increase standby efficiency and reduce maintenance to very low levels.

Typically, the high-mass flywheel is used in conjunction with a motor-generator system. These units can be configured as:^[7]

1. A motor driving a mechanically connected generator,

2. A combined synchronous motor and generator wound in alternating slots of a single rotor and stator,

3. A hybrid rotary UPS, designed similar to an online UPS, except that it uses the flywheel in place of batteries. The rectifier drives a motor to spin the flywheel, while a generator uses the flywheel to power the inverter.

In case No. 3 the motor generator can be synchronous/synchronous or induction/synchronous. The motor side of the unit in case Nos. 2 and 3 can be driven directly by an AC power source (typically when in inverter bypass), a 6-step double-conversion motor drive, or a 6-pulse inverter. Case No. 1 uses an integrated flywheel as a short-term energy source instead of batteries to allow time for external, electrically coupled gensets to start and be brought online. Case Nos. 2 and 3 can use batteries or a free-standing electrically coupled flywheel as the short-term energy source.

Applications

N+1

In large business environments where reliability is of great importance, a single huge UPS can also be a single point of failure that can disrupt many other systems. To provide greater reliability, multiple smaller UPS modules and batteries can be integrated together to provide redundant power protection equivalent to one very large UPS. "N+1" means that if the load can be supplied by N modules, the installation will contain N+1 modules. In this way, failure of one module will not impact system operation.

Multiple redundancy

Many computer servers offer the option of redundant power supplies, so that in the event of one power supply failing, one or more other power supplies are able to power the load. This is a critical point – each power supply must be able to power the entire server by itself.

Redundancy is further enhanced by plugging each power supply into a different circuit (i.e. to a different circuit breaker).

Redundant protection can be extended further yet by connecting each power supply to its own UPS. This provides double protection from both a power supply failure and a UPS failure, so that continued operation is assured. This configuration is also referred to as 1+1 or 2N redundancy. If the budget does not allow for two identical UPS units then it is common practice to plug one power supply into mains power and the other into the UPS.

Outdoor use

When a UPS system is placed outdoors, it should have some specific features that guarantee that it can tolerate weather with a 'minimal to none' effect on performance. Factors such as temperature, humidity, rain, and snow among others should be considered by the manufacturer when designing an outdoor UPS system. Operating temperature ranges for outdoor UPS systems could be around −40 °C to +55 °C.

Outdoor UPS systems can be pole, ground (pedestal), or host mounted. Outdoor environment could mean extreme cold, in which case the outdoor UPS system should include a battery heater mat, or extreme heat, in which case the outdoor UPS system should include a fan system or an air conditioning system.

Internal systems

UPS systems can be designed to be placed inside a computer chassis. There are two types of internal UPS. The first type is a miniaturized regular UPS that is made small enough to fit into a 5.25-inch CD-ROM slot bay of a regular computer chassis. The other type are re-engineered switching power supplies that utilize dual power sources of AC and/or DC as power inputs and have an AC/DC built-in switching management control units.

Machine standards

Measuring efficiency

The way efficiency is measured varies massively in the UPS market, and there are a number of reasons for this. Many UPS manufacturers claim to have the highest level of efficiency, often using different sets of criteria in order to reach these figures. The industry norm can be argued to be anything between 93%-96% when a UPS is in full operational mode, and to reach these figures companies often put their UPS in an ideal scenario. Efficiency figures on site are often much closer to the 90% mark, due to varying power conditions. The perfect scenario will never happen in reality, due to ongoing voltage sags from the mains and the declining efficiency of UPS batteries.

Warranty

Warranty on uninterruptible power supplies has varied over the past couple of years, often depending if a machine is Single Phase or Three Phase. Few companies compete on warranty, with the focus mainly on efficiency and maintenance contracts. The standard manufacturers warranty is anything between 1–2 years and can even be limited to certain aspects of the machine, often excluding the more expensive items such as battery replacement. Focusing on one market, companies supplying Three Phase however now offer lengthier warranties, with the norm closer to 2 years rather than the single year.

Difficulties faced with generator use

Frequency variations

The voltage and frequency of the power produced by a generator depends on the engine speed. The speed is controlled by a system called agovernor. Some governors are mechanical, and some are electronic. The job of the governor is to keep the voltage and frequency constant, while the load on the generator changes. This may pose a problem where, for example, the startup surge of an elevator can cause short "blips" in the frequency of the generator or the output voltage, thus affecting all other devices powered by the generator. Many radio transmission sites will have backup diesel generators – in the case of amplitude modulation (AM) radio transmitters, the load presented by the transmitters changes in line with the signal level. This leads to the scenario where the generator is constantly trying to correct the output voltage and frequency as the load changes.

It is possible for a UPS unit to be incompatible with a generator or a poor mains supply; in the event that its designers had written the microprocessor code to require exactly a 50.0 Hz (or 60.0 Hz) supply frequency in order to operate; with this condition not met the UPS could remain on battery power, being unable to reconnect the unsuitable supply voltage.

This problem of input frequency requirements should not be an issue through the use of a Double Conversion / online UPS. A UPS of this topology should be able to adapt to any input frequency, using its own internal clock source to generate the required 50 or 60 Hz supply frequency.

Power factor

A problem in the combination of a "double conversion" UPS and a generator is the voltage distortion created by the UPS. The input of a double conversion UPS is essentially a big rectifier. The current drawn by the UPS is non-sinusoidal. This causes the voltage from the generator also to become non-sinusoidal. The voltage distortion then can cause problems in all electrical equipment connected to the generator, including the UPS itself. This level of "noise" is measured as a percentage of "Total Harmonic Distortion of the current" (THD(i)). Classic UPS rectifiers have a THD(i) level of around 25–30%. To prevent voltage distortion, this requires generators more than twice as big as the UPS.

There are several solutions to reduce the THD(i) in a double conversion UPS:

Passive power factor correction: (Passive PFC)

Classic solutions such as passive filters reduce THD(i) to 5–10% at full load. They are reliable, but big and only work at full load, and present their own problems when used in tandem with generators.

Active power factor correction:

An alternative solution is an active filter. Through the use of such a device, THD(i) can drop to 5% over the full power range. The newest technology in double conversion UPS units is a rectifier that doesn't use classic rectifier components (thyristors and diodes) but high frequency components (IGBTs). A double conversion UPS with an IGBT rectifier can have a THD(i) as small as 2%. This completely eliminates the need to oversize the generator (and transformers), without additional filters, investment cost, losses, or space.

Communication

Power management requires the UPS to report its status to the computer it powers, via a serial port, Ethernet or USB, and a subsystem in the OS to handle the communication and generate notifications, PM events or command an ordered shut down. Manufacturers that publish their communication protocols make integration easy. However some manufacturers like APC use proprietary protocols.

Calculating on-battery runtime

The run-time for a UPS depends on the type and size of batteries and rate of discharge, and the efficiency of the inverter. The total capacity of a lead-acid battery is a function of the rate at which it is discharged, which is described as Peukert's law. Manufacturers supply run-time rating in minutes for packaged UPS systems. Larger systems (such as for data centers) require detailed calculation of the load, inverter efficiency, and battery characteristics to ensure the required endurance is attained.

Source: Wikipedia, the free encyclopedia

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