3GS - 3rd Generation Steelmaker

Twitter Stream

I haven't been updating this page lately because I'm trying to sell a house and back and forth between Illinois and Iowa with limited internet access at times. Additionally, I am still doing consulting work and software development. I have been using twitter because it is much easier and faster from the droidx. You can follow my twitter stream here or from the link in the sidebar.

I have started working on a few steelmaking tech write-ups and hope to finish/post one of them here sometime soon. Sorry for the lack of activity. [more]

Update

Wow, it has been a really long time since I added anything to this blog (I hope it still works). I am going to try to write some more technical things and post them here sometime soon.

Quite a bit has happened. I accepted an Electrical Engineering position with Sterling Steel in Sterling Illinois. Sterling Steel was formerly Northwestern Steel and Wire. I started in June and it is working out really well. I think that there is enough work there to keep me busy for the rest of my career. Actually, I think I could keep several Engineering Interns/Co-ops busy as well.

I am trying to sell my house in Iowa. I have been back and forth between Sterling and Iowa a lot since June.

I went to the AIST globetrotters conference in Salt Lake City in October. It was a good meeting. I am very glad that I went because I was able to see my former boss and friend Stuart Gray who passed away the following month in November. The steel industry lost a true pro. [more]

New Phone

Wow, it has been a while since I posted anything here, sorry about that. I have had some changes and have been tied up on some things. I will say more later.

I bought an iPhone a little over a year ago and signed a contract with ATT. The ATT network was marginal at best when I was traveling and when I was in Memphis, but it is horrible in Iowa/Western Illinois. My wife had Verizon anyway so I decided to cancel the iPhone, pay ATT their fee and get a DroidX.

The iPhone is a nice phone, but ATT's network is a real problem. A lot of the issues that I thought I had with several models of Blackberry were actually ATT's junk network. The DroidX is an excellent phone. I don't want to write another review of it, there are plenty out there already. I just wanted to mention a few things about it.

Some reviews have claimed that the droid interface is confusing. I agree that it is a little different at first, but it isn't that big of a deal. I think the problem is that it is not completely consistent. It really is not that big of a deal, it just takes a few minutes to wrap your head around it. The Droid can be configured to look like pretty much whatever you want it to, it just takes a few minutes of work.
There is no front facing camera (like the iPhone 4). I couldn't care less, I wouldn't use it anyway. I doubt that ATT's network is going to handle it anyway.
Verizon's 3G network is very nice (in Eastern Iowa/Northwestern Illinois anyway).

My cell number has not changed by the way. [more]

Obesity Epidemic

33% of the USA is considered to be Obese. Harley Davidson suspensions never cease to amaze me. [more]

Lame Excuses for Lack of Activity

Sorry for the lack of activity here. I have been really busy lately. I have some things I want to post but just haven't had the time. This weekend may not be much better. [more]

GNA Stock

I think that GNA (probably GGB also) really needs to consider buying back some of their stock. I was trying to understand why GNA has so much price volatility and I think that the number of shares may be part of the issue. Check out the stats on some of their competitors:

Company	Market Cap	Shares
GNA	$3.05B	433.49M
CMC	$1.64B	114.19M
NUE	$13.49B	315.10M
STLD	$3.03B	216.33M
X	$6.75B	143.38M

[more]

IBM Re-Inventing Itself Again?

Business types like to talk about how IBM has always managed to re-invent itself over the years to remain relevant. This months IEEE spectrum has an interesting article that may give an indication of what their next act will look like. [more]

Metal Theft

The NY Times has an article about the evolution of metal theft. It is interesting that metal theft is up considering how much scrap prices have declined in the last few years. [more]

Short Circuit Power

This is the fourth article of a series covering various aspects of AC Electric Arc Furnace (EAF) power system and control technology. The goal of these articles is to provide a high-level analysis of each topic, utilizing more pictures and words than mathematics, however, I am deviating from the goal again this month and writing something that is almost entirely mathematics. More in-depth analysis, training and/or consultation is available. Please see this page for contact and proposal information. Previous EAF technology articles can be found through this link. Feedback is always welcome.

I have been busy since the last article was posted. This article will be short, but it does cover something that has great practical significance. The goal of this article is to show what is meant by short circuit power/level. This metric is utilized extensively in order to gauge the degree to which a power delivery system can support a load, which happens to be an EAF in this case.

Short circuit level is actually a very simple metric if you understand per-unit analysis. If you do not understand per-unit analysis then consider commiting some time to studying it because it is ubiquitous in the power industry and it will actually make your life easier if you need to do power system analysis.

S_b = sqrt(3) V_bI_b	(1)
S_sc = sqrt(3) V_bI_sc	(2)

Equation (1) is just the three phase apparent power relationship using base quantities. Equation (2) is the definition of three phase short circuit apparent power. Note that voltage is the base (nominal) voltage and that the current is the short circuit current.

Dividing (2) by (1):

S_sc/S_b = I_sc/I_b	(3)
S_sc p.u. = I_sc p.u.	(4)

Recall that dividing a quantity by a base quantity results in a per-unit value. This means that the per-unit short circuit apparent power is equivalent to the per-unit short circuit current as is shown (4).

I_sc p.u. = 1 / \|Z\| p.u.	(5)
S_sc p.u. = 1 / \|Z\| p.u.	(6)

The primary voltage source in a per-unit system has a magnitude of 1 and so we can develop (5) and (6) using this relationship. Note that this assumes that the system impedance is the short circuit impedance.

\|Z\| p.u. = S_b / S_sc MVA	(7)
\|Z\| p.u. = 100 / S_sc MVA	(8)

Using (6) we can develop (7) and (8). This shows that given the short circuit level in MVA at any point in the system, the magnitude of the per-unit equivalent impedance can be calculated. A 100 MVA base is assumed in (8). (7) and (8) explicitly show that short circuit MVA is really just an indication of the system equivalent impedance.

Many approximation techniques used for EAF power system analysis rely on knowledge of short circuit level in MVA. Utilities tend to maintain their system databases in per-unit impedance and will provide system impedance in per-unit to your system bus. This is no problem since we can utilize (7) or (8) in the other direction.

As an example, assume that our plant manager tells us that he/she wants to increase production in the melt shop by installing a larger EAF transformer. He/She asks us to investigate and estimate the largest EAF transformer the existing system will support. We are not sure what the latest utility configuration can provide in terms of short circuit MVA to our facilities high voltage bus so we send an e-mail to our utilities representative asking for the information. Three months later we receive a reply that the impedance to our high voltage bus is 0.02 per-unit on a 100 MVA base. Using (7):

S_sc = 100 / 0.02 MVA = 5000 MVA

assuming that we have an uncompensated system and contractual power quality obligations we estimate that we can support approximately 60 MVA. [more]

Safety of Flight Issue

I have been reading and listening to complaints by the EU airlines and news organizations over how long air traffic control kept the airspace closed due to the volcanic ash. I spent the first 4 years of my professional career as a flight control and instrumentation specialist on US Air Force tactical aircraft. We would always joke that our systems were so critical to safety of flight that we had a "get out of jail free card", meaning that if we had any doubts at all about the integrity of an aircraft we had a great deal of authority to keep the aircraft grounded. We (flight control specialists) took safety of flight very seriously, we had to, the Air Force had all the authority in the world to hold us liable for mistakes (as they should).

I still take safety of flight issues very seriously (I am sure that my former colleagues do as well). My position now is the same as it was then, if there is any doubt at all concerning the safety of flight, do not fly, end of story. I commend the EU airspace control authority for erring on the side of safety. It is not always the convenient side to take, but it is so much better than the alternative. [more]

Monday Morning Quote

You've got a lot of choices. If getting out of bed in the morning is a chore and you're not smiling on a regular basis, try another choice - Steven D. Woodhull. [more]

Three Days of the Condor

I watched a "classic" 1975 movie the other night, Three Days of the Condor. Robert Redford was the lead in this movie, and was good. I had heard of this movie, but never watched it. I can recommend it. It was worth 2 hours of my week. [more]