ISO PHASE BUSBAR
ISO PHASE BUSBAR
(OP)
How are conductivity tests conducted on 21Kv,15000A isophase bus during erection and after in service.
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RE: ISO PHASE BUSBAR
If you want better precision then you will probably have to rig your own test using some sort of high current DC supply and a precision meter. I have used that technique on 18kA bars and it works well: I used a HP6681A power supply and a Keithley type 2000 bench meter. Beware of thermal EMFs in test leads, and make sure you fully understand how a Kelvin four-terminal resistance measurement connection works to avoid getting silly errors.
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RE: ISO PHASE BUSBAR
RE: ISO PHASE BUSBAR
The HP supply has enough voltage output to drive current one end of the bus to the other so we used welding cable and bolted connections at the flexible links for the generator and transformer connections. Resistance measurements were performed at all bolted joints. The key things we found were to inject current well away from where you are placing the voltage probes either side of the joint, and to reverse the voltage probes and repeat the measurement then average the two values to compensate for any thermal EMF. Transformer bushings are awkward because it is difficult to inject current away from the voltage measurement point but there's usually a way of doing it.
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If we learn from our mistakes I'm getting a great education!
RE: ISO PHASE BUSBAR
RE: ISO PHASE BUSBAR
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If we learn from our mistakes I'm getting a great education!
RE: ISO PHASE BUSBAR
Idon't know of any inspecton othere than visual. X-Ray would work but I have heard of it being used.
If you get a good weld with good records shy test it?
RE: ISO PHASE BUSBAR
I agree with your sentiments about testing welded joints, the joints I was testing were foil laminated, bolted joints from bushings to bus duct and the figures I quoted were for that type of joint.
Over here dye-penetrant is a common weld inspection method, as is ultrasonic. Both would require the weld to be dressed before the test, not something which the IPB manufacturers would normally do.
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If we learn from our mistakes I'm getting a great education!
RE: ISO PHASE BUSBAR
We have good 750 A AC injection tester and I wonder whether it is acceptable to perform these measurements by A-V scheme using AC-source. It is clear that we will measure impedances instead of pure resistances, but acc. to me the difference will not be significant.
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RE: ISO PHASE BUSBAR
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If we learn from our mistakes I'm getting a great education!