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I was able to get a copy of ETAP and model this circuit. The line to ground current on the 208V side was 5.6kA. The three phase currents at the 480V switchgear were: A phase - 1.46kA -69.5 degrees B phase - 0A 110.5 degree C phase - 1.46kA 110.5 degrees All three phase currents sum to 0, so...

It is a 600A panel. So the 480V breaker did not trip, because it did not see any fault current due to the delta/wye transformer. The blast from the fault blew the cover away from the terminals and removed the fault. That's pretty much what I thought. Thanks for the help.

No the 208V main in the panel did not open either.

I have 208/120V panel fed from a delta / wye transformer. Upstream of the transformer is a 480V switchgear with electronic trip breaker. The GF on this breaker is a residual sensor and is set at 140A. The transformer is about 150' from the switchgear, and the panel is 20' from the...

smallgreek - would you happen to have or know where to get a schematic of the relay that would show this resistor?

Thanks for the help. It looks like the DC powers the relay and also is connected to the trip circuit. http://www05.abb.com/global/scot/scot229.nsf/veritydisplay/bbb91a5aaaed72c485256eac007356a6/$file/ib7.2.1.7-1c%20%20%20%20%20%20%2051%20223%20423.pdf

Cat# 223P2210 I've been thinking about putting a resistor on the voltage input of the relay to drop the 175VDC down to 125VDC. Any thoughts on this?

Yes 175. This is the oddball substation on site. All others are 125

I have an old ABB Circuit Shield 51 relay that has gone bad. It has control voltage of 175VDC. If I find another relay, same model but with a different control voltage, does anyone know of a way to modify the relay to accept 175VDC control voltage?

Thanks everyone. I think we convinced our electrician group to check the measurements at the CT's.

We want to measure the amp load on a 2400V motor. Can we use a fluke clamp on meter that is rated for 600V? If not, how would you suggest we obtain this data?

FYI, here's a brief description from the boiler vendor. The model HVJ is a high voltage jet-type boiler in which water from the lower part of the boiler shell is pumped by either an internal or external circulation pump to the nozzle header and flows by gravity through the jets to strike the...

Waross - Thanks for the information. We have changed paths a little and are looking at installing a 13.8KV 1:1 isolation transformer with a gounded wye secondary to give us a solid neutral point. Thats correct waross, the water acts as a conductor between the nozzle and the plate. The...

We are looking at putting in a new electric fired boiler. Our understanding of how the boiler works is as follows. Water is sprayed from a nozzle onto energizered plates. The nozzle is connected to neutral and the plates are energized with 13.8KV. This vaporizes the water into steam. Our...