TNB Electrical Engineer

Cable Construction 1 core XLPE

2010-01-07T11:39:00.001+08:00

Background of XLPE used

Early 1990's, began to be used for 11kV and 22kV.

The need to carry a load > 300A or 7 MVA

Example: interconnector between PMU-PMU, PMU-PPU or LPC (>10MW)

33kV 1C 630 mmp = 30 MVA
11kV 1C 500mmp = 10MVA
11kV 3C 240mmp = 6.7 MVA

Current Transformer

2010-01-01T16:16:00.000+08:00

A current transformer (CT) is a transformer which measures the current of another circuit. It is coupled to an ammeter (A in the diagram) in its own circuit to perform this measurement. Measuring high-voltage current directly would require insertion of measuring instrumentation into the measured circuit--an unnecessary difficulty which would draw down the very current meant to be measured. Also, the heat generated in the measuring equipment from the high current could give false readings. Measuring current indirectly with a CT is much more practical.

Application

Current Transformers (CT’s) are instrument transformers that are used to supply a reduced value of current to meters, protective relays, and other instruments. CT’s provide isolation from the high voltage primary, permit grounding of the secondary for safety, and step-down the magnitude of the measured current to a value that can be safely handled by the instruments.

Common Uses

Electric Meter

The one central function of a CT is to determine the current in a circuit. This is especially useful for monitoring high-voltage lines throughout the power grid. Another ubiquitous use of CTs is in domestic electric meters. A CT is coupled with a meter to measure what electrical usage to charge the customer.

Current Transformer

Another function of CTs is protection of sensitive measuring equipment. By increasing the number of (secondary) windings, N2, the current in the CT can be made much smaller than the current in the primary circuit being measured. In other words, as N2 in the formula i1/(2πr) = i2 --- N2 goes up, i2 goes down.

This is relevant because high current produces heat which can damage sensitive measuring equipment, such as the resistor in an ammeter. Reducing i2 protects the ammeter. It also prevents heat from throwing off the accuracy of the measurement.

Protective Relay

CT Mounted Over Bushing of Circuit Recloser

CTs also protect the main lines of the power grid. An overcurrent relay is a type of protective relay (switch) that trips a circuit breaker if a high-voltage current exceeds a certain preset value. Overcurrent relays use a CT to measure the current, since the current of a high-voltage line could not be measured directly.

Magnetising Curve test

2009-12-31T06:15:00.002+08:00

Test Terminal Block Female

Test Terminal Block Male

This tool is intended to test every relay in the control panel. Yesterday i went to PPU Tanjung Tokong to see the contractor do the test for over current relay. Test whether the magnetic curve or not functioning properly.

Current Transformer test

2009-12-30T10:09:00.001+08:00

This person is one of the TNB's Contracter. They were doing testing for Current Transformer. They will inject current to secondary of the CT then the result to find the bending in curve.

Example: First result they get current value is 40 A then voltage they get 37 volt. for the next reading plus 50% from previous read that means 60A the voltage result must get 10% from previous reading that means for 60A they must get 39.7V

Water Tree in XLPE Cable.

2009-12-28T22:03:00.000+08:00

What is Water Tree?

Water tree degradation is a major problem for medium voltage XLPE cables. One the Most important degradation process of the polymeric insulation that contributes to the failure of the cable

Why it call Water Tree?

Water Trees are a diffuse structure in the polymer resembling the shape of a tree or bush.

How it cause?
Water Tree are formed and grow in the presence of moisture, impurities or contamination@ and electric field over time.

There are generally two types of water trees, namely; )

Bow-Tie Tree

Vented Trees

Water Treeing - Bow-Tie tree

Bow-Tie trees are water trees that grows from the insulation outwards towards the surfaces of the insulation.

These trees grow in the direction of the electric field in both directions, towards the two electrodes.

Bow-Tie trees have faster initial growth rate as compared to vented trees.

Bow-Tie trees are however, not capable to growing to large sizes and usually do not grow to a size significant enough to cause failure of the insulation

Water Treeing – Vented tree

Vented Tree are water trees that grows from the surface of the polymer inwards into the insulation system.

These trees will grow in the direction of the electric field.

Vented trees have lower initial growth rate as compared to bow-tie tree

Vented trees are capable of growing right through the entire insulation thickness.

This is the more venomous of the two trees as these trees as it is of bridging the insulation system across two electrodes.

Finally finished load transformer

2009-12-27T00:18:00.000+08:00

He he he. although yesterday a public holiday, but I still want to know how a transformer removed from the truck to the transformer plinth.

I think me already be late to witness loading transformer. But I am lucky. When I arrived at PPU Kepala Batas they just start their work setup the accessories.

Transformer load

2009-12-24T20:22:00.000+08:00

Today I should can see how a transformer be shift to transformer plinth, but disappointing. The reason cause the lift that will remove the transformer not able reach in time because the transports punctured tyre in Gopeng, Perak.

After that at 4pm I follow up position the lorry. they said already were in Bukit Merah, Perak. Inside possibility hit 6 in the evenings the truck will reach.

From 2009-12-24 :
workers are making preparations for the loading to Tx Plinth

From 2009-12-24
Another transformer are waiting for loading

Before I forget the place at PPU Kepala Batas, Penang. Near to Pak Lah Badawi Hometown.
Below is about transformers' detail.

From 2009-12-24

land area and building substations size

2009-12-23T15:29:00.000+08:00

Following is building land area and size an ordinary used in division system.

Following is fundamental component layout for PMU

Tx is abbreviation for Transformer

Cap is abbreviation for capacitor

NER is abbreviation for Neutral Earth Resistant

Substation Categories, Type & Design

2009-12-23T11:15:00.000+08:00

Sub-station categories

Transmission Main Intake (Pencawang Masuk Utama-PMU)

View from the front of PMU Sebarang Jaya, Seberang Perai,Penang.

Transmission Main Intake is the interconnection point of 132kV or 275kV to the distribution network. The standard transmission capacity and voltage transformation provided at the PMU are as follows:-

- 132/33kV, 2 x 90 MVA
- 132 /22kV, 2 x 60 MVA
- 132 /11 kV, 2 x 30 MVA

Main Distribution Sub-station (Pencawang Pembahagian Utama- PPU)

View from the front of PMU Pulau Tikus,Penang.

Main Distribution Sub-station is normally applicable to 33kV for interconnecting 33kV networks with 11 kV networks. It provides capacity injection into 11 kV network through a standardized transformation of 33/11 kV.

Main Switching Station (Stesyen Suis Utama- SSU)

 View from the front of SSU Seagate.

SSU at 33kV, 22kV and 11 kV are established to serve the following function:-

1. To supply a dedicated bulk consumer ( 33kV, 22kV, 11 kV)

2. To provide bulk capacity injection or transfer from a PMU/PPU to a load center for further localized distribution. 

Distribution Substation (Pencawang Elektrik – P/E)

Side view of P/E Komtar Telekom Exchange

Distribution sub-stations are capacity injection points from 11 kV, 22kV and sometimes 33kV systems to the low voltage network (415V, 240V). Typical capacity ratings are 1000kVA, 750kVA, 500kVA and 300kVA.

Conventional substation designs are of indoor type (equipment housed in a permanent building) and out-door type (ground-mounted or pole-mounted). Standardized M & E design of 11/. 433kV sub-station is available at TNB offices. Compact substation (11 /. 415kV) has limited application and is to be strictly applied in selective situations under the following circumstances:-

§ System reinforcement projects for highly built-up areas where substation land is difficult to acquire.
§ Any request to use compact substation for dedicated supply to a single or limited group of low voltage consumers is subject to TNB approval in accordance to site constraints situation, and to be considered as ‘special feature design schemes’.

Tenaga Nasional Berhad

2009-12-22T12:57:00.000+08:00

Tenaga Nasional Berhad (TNB) is the largest supplier of electricity throughout Malaysia with assets exceeding RM 54.0 billion and provides services to more than 5 million customers throughout Peninsular Malaysia and Sabah and Sarawak.

TNB's core activities are Generation, Transmission and Distribution of electricity. Until now TNB plays an important role in the Power Generation and the main form in which the diversity of business for the company TNB. TNB Generation through wholly owned by TNB, it can generate electricity generation capacity of the largest of approximately 7100 MW which includes approximately 61% of total power generation of Peninsular Malaysia.

Was present, TNB has a complete power supply systems, including National Grid, Customer Service Center, Management Call Center and office administration for Peninsular Malaysia, Sabah and Sarawak. Beside that also, TNB operates two Universities, namely Universiti Tenaga Nasional (UNITEN) in Bangi campus and Robin Gray Pahang.

TNB through its subsidiaries also are involved in manufacturing or supply Transformer, High Voltage Cable & Switchgear. Provide Professional Consultancy Service, fuel, Logistics 'freight & Insurance Coverage' research and development and Property Development & Project Management Service, Architectural field, Civil and electrical engineering and services.

Tenaga Nasional Berhad (TNB), a public listed company registered under Companies Act 1965, is charged with the following responsibilities

· To generate, transmit, distribute and sell energy to consumer throughout Peninsular Malaysia.

· To plan, install, operate and maintain electricity installation for the generation, transmission and distribution of electricity.

To achieve the objectives, the company owns and operate power plants and the National Grid, and installed for this purpose, consumer service centers, call management centers, substations and administrative offices throughout Peninsular Malaysia. TNB’s core activities are in generation, transmission and distribution of electricity which are being handled by 3 Divisions:

· Generation Division

· Transmission Division

· Distribution Division

Joint for Fiber Optic

2009-12-22T07:57:00.000+08:00

Yesterday I went to see how a jointer to joint fiber optic.

I went to B Braun (front B Braun). look at the joint fiber optic. Other than the others. unlike cable joint for 11kV or 33kV.

This kind type for fiber optic joint

knowing me

2009-12-21T13:35:00.000+08:00

My name is Mohd Qayyuum bin Kamarudin. Graduate from University Malaysia Pahang (UMP) in Electric Engineering (Electronic).

I am now undergoing a program that recommended by Khazanah Nasional under the provisions of the Finance Ministry. The name of the program is the Graduate Employ-ability Enhancement Scheme (GEMS). In the program they have been taught theories of office management, the syllabus had been taught by them are:

1) Excellent Personal,
2) Business Appreciation,
3) Project Planning,
4) Time Management,
5) Office Management,
6) Operation Management,
7) Customer Service,
8) Presentation Skill,
9) Problem Solving,
10) Interpersonal Communication,
11) Personal Grooming

Almost two months and at Harvard Suasana Hotel, we spent the waste of life, we learn there all the knowledge they teach as above. After exhausted al in our head then we been placement for our attachment job in any government link company (GLC).

I elected to undergo attachment job in TNB. On 28 Sept 09, I went to Tenaga Nasional Berhad, Pejabat Pengurus Besar Pulau Pinang, Jalan Anson. I went there for my self report. I meet with En Shahidan then I been introduce by En Shahidi to my mentor Ir Haji Md Jailani.

I already been here for 2 month, now I with my mentor under project unit.