impedance of current transformer

wrote:
| There aren't very many labs left in the world that can do the type of | testing you are talking about. Our lab in Lenox MA
| (http://www.eprisolutions.com/EPRIsolutions/transmission/tdhvtesting.htm ) | only does up to 10,000A surges. I think BC Hydro may still have a lab that | can test at 100 kA. I know of a couple of European labs and perhaps a | couple of Asian labs that can perform that kind of testing. Many utilities | used to have those kinds of labs, but sadly most have completely abandoned | their labs and the few that remain have retired their higher current | equipment. I run our low voltage lab | (http://www.epri-peac.com/about/pdfs/testing_for_viewing.pdf ) and we can do | a few thousand amps if we really need to. | | It just hasn't been economical for utilities/companies to maintain those | kinds of testing capabilities, with the exception of breaker manufacturers. | It is certainly not something you are going to want to try to build on your | own.
I'm not interested in trying to build such a test lab. But I am curious what goes into the making of one. What would breaker manufacturers like Cutler-Hammer, GE, Siemens, and Square-D use to test their 600 volt class breakers? And what would UL use to indepedently verify the interruption ratings?
And then there are test procedures. How many units would need to be tested for valid sampling? How many tests would have to be performed on a single unit? Would the test involve closing a bolted fault on the load side of an energized and closed breaker? Would that test be limited to a cold breaker, or would it be applied to a breaker running full rated current and voltage for a few hours? Would the test involve closing the breaker onto an already bolted fault? Would the test involve energizing a breaker already closed onto a bolted fault? Would power factors less than unity be tested at fault current levels? Would every combination of phase faulting be tested?
What kinds of testing would be appropriate for a newly constructed home to verify that the electrical work meets specifications (and not just passes inspection)? If I have 200 amp service and a 200 amp main breaker, I should expect that if I run test loads above 200 amps I should have a main trip within certain times at certain current levels based on the manufacturer trip curves. At what point could such testing risk damaging the system?
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| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
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wrote:

There are probably standards (IEEE/ANSI) that answer your questions. We don't test molded case breakers, so I am unfamiliar with the standards. I am not sure how your running a CT in reverse is going to answer your question either.
Charles Perry P.E.
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wrote:
| There are probably standards (IEEE/ANSI) that answer your questions. We | don't test molded case breakers, so I am unfamiliar with the standards. I | am not sure how your running a CT in reverse is going to answer your | question either.
Running a CT in reverse is not going to answer them. But having the answers might provide added safety details to consider. I'll probably go sign up on one of the Tesla coil forums and ask those guys. They know how to push the envelope in one direction and might have an idea about the other.
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wrote:

You keep changing your mind. First you asked about making lots of current. As people began answering, you said you were really after the answers to about a dozen questions related to breaker testing. Now you just want to make lots of current again.
Charles Perry P.E.
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wrote:
| You keep changing your mind. First you asked about making lots of current. | As people began answering, you said you were really after the answers to | about a dozen questions related to breaker testing. Now you just want to | make lots of current again.
Why would I put both in the same posting? What inspired the first post was the CT question. It's not the only question I have; it's the one I picked to post first. Then testing was mentioned, and that connected with already existing questions that hadn't been posted yet (but might have been some day). It's not "changing my mind". All the questions are valid.
And yes, if I ever do build a high current system, I probably will do some destructive "testing" (demonstration is more like it) on things like small wires and fuses. With the lower voltage it might not be as spectacular as it could be (I'm not likely to be building a 100 MVA generator).
I'm just thinking about it for now, and trying to figure out what might be doable, without costing too much moeny, and still maintaining a level of safety at least equivalent to what the HV experimenters do. The voltage might not be able to jump out at me, but there could be a big arc flash if something shorts out.
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Here Ya Go ! Rudimentary but Do-able.
Get a Frankenstien Sized Twin Blade Switch. 5-600A or anything rated way over your 200A. Wire up One Leg of your 200 Amp circuit to it <~> 110V [from Buss bore a Tap/Die a hole for a screw terminal if none available] with CB off of course, use a Cordless Drill/Driver for this };-) but do not tap off your Main it won't work well @#};-)
On the other Terminal of your Giant Blade Switch to >~< Ground
***Carefully *** };-o
Of Course: you'll Screw this Giant Switch Down on an Insulated surface.
Place a Clamp on Ammeter on it for monitoring.We're all Professionals here, so, have a qualified & experienced Helper to assist you:) ru near nyc ?
NOTE *** use Gloves and any pertinent or paranoid protection you can muster.
Firmly Throw the Switch }:-) !!!!!
see record how & where it cuts off and trips the CB. tell us about it }:-)
Have a Nice Weekend !
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Now, you know I am Jesting a little about this method of testing the Mains on a Panel.
I'm sure there is a trip tester somewhere out there like the ones designed for GFCI's., but if you're thinking I'm all funny about it, I'm not, I'd test it in a similar fashion if i had need to.
Boring the Buss for a Solid Tap may damage or weaken your Panel., done out of the way of cb placement tabs and leaving the tap screw securely in place after the test, should maintain it's integrity.
Since this has nothing to do with Impedance nor the OP I submit I find it interesting and feasible., but not a likely course of action for the average person.
I'm sure the Monster Blade Switches are available where ever High Voltage Products are sold :-)
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...
Try www.bussmann.com/services/gubany/gubanyCapabilities.asp
s falke
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I didn't write this- but thanks anyhow.
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Don Kelly
snipped-for-privacy@peeshaw.ca
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Aaak! Sorry Don. I try to be careful with attributions, but sometimes..
s falke

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