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Section 18-152(8) of the CEC says: "Cable glands shall be compatible with the degree of protection and explosion protection provided by the enclosure that the cable enters, where the area classification and environmental conditions require these degrees of protection" My question is, if I have...

Just wanted to get an opinion on whether the windings of a transformer should be shorted together when performing an insualtion resistance test on a transformer. I was taught to always short them, however some people believe it does not matter. I know when you perform a capacitance and...

Hey pocketchange, I just came back from site where they had a 735 fail and it triggered the fire supression system before blowing the control fuses in the panel. This relay is also being fed off a set of bus PT's. I talked to GE and they said nothing like this has ever happened before... yeah...

Hey Waross, It is quite possible that may be the case. THere are transformers, reclosers, arrestors etc. on this line and there are radio communications in the area too. This seems like the best answer I have gotten so far, as I do not think it is an issue with the CT's or wiring. As the...

Hey old field guy, When testing the ratio of the CT's using the voltage method via a ratio meter, I had removed the leads right off the relay case and tested the whole secondary circuit back to X1-X2 of the CT's. I asumed any increased burden in the circuit should have shown up on my ratio.

Hi Slava Thanks for the input, I did test the ratio and saturation curves on the CT's, with no apparent problems.

Yes when the unit tripped, the camp feed stayed energized via the grid. The load on the feeder was less than 50 kW. There is overcurrent protection on this feeder, but nothing operated.

Well I was able to fly out yesterday when we got it back on line, but off again tomorrow morning!

Hey GT The unit is now running with rated load on it. It was just when this line was in the circuit that the trip occured.

This relay does not have event recording capability, the Diff CT's are C100, the distance between the CT's and protection panel is ~10 meters, and the CT wire size is 10AWG.

Ct's on the differential zone are 800:5, relay set at 0.4. CT's on the feeder are 200:5, relay set at 1.5 amps sec trip level.

No this unit was online when it tripped, has been in service for years. I tested the Diff Relay and it tested fine, none of the CT's are shorted, loop checks were performed on all CT circuits, and the CT's were ratioed and sauration tests performed.

I was recently called out to a hydro site that had an 8 MW, 6900V unit trip on A,B,C differential (Basler BE1-87G). Within the neutral and phase CT's is a tap to a Static Exciter Transformer. Outside of the CT's, but still on the generator side of the Generator breaker is a surge pack...

Yes, actually this is why I want to de-magnetize, I was doing the Doble tests on the transformer, and I didnt get the characteristic High-Low-High on my excitation test, so Doble recommended I de-magnetize the transformer and try again. Thanks

What is the best and easiest way to de-magnetize the core of a 7.5MVA 34.5/25 kV transformer. Thanks

Does anybody know where a guy could get parts for a Baur Phasing Scope meter, I mangaged to smash the bulb in mine today. Thanks

Looking for a code or CSA Standard for reasons why metering PT's must be in an enclosure when used in a disconnect switch