ECN Forum Forums General Topics of the Trade General Discussion Area elevator trips 2000A main

I haven't dealt with this problem personally. Fellow employees relayed the limited information I have to me. I will find out more tomorrow and try to be more specific with my query. Thanks to all for the help so far.

"I agree there is not enough info to tell you what is wrong but my guess is the ST delay setting is low (quick). Either your engineer is clueless about coordnition studies (Main tripping before the feeder?!?!) or your trip unit is bad and needs to be tested via primary injection."

That's about it.

480V

Main breaker:
GE SSF20B220
2000A rating plug
short term setting 1.5x to 9x
set at 8x
trips short term 17-21KA

Downstream Breakers
GE SGHB36BDO600
600A rating plug
short term set at 5x

125A therm/mag

100A TD fuses




[This message has been edited by triple (edited 11-08-2005).]

The only time I've seen this problem it was as Dave T. described. Once the GF settings were adjusted to the proper level the problem disappeared.

That model Power Break II Circuit Breaker typically has adjustable long time pickup, long time delay, short time pickup, short time delay, Instantaneous and ground fault pickup.
short time pickup at 8x2000A = trip from 14,000A to 18,000A considering manuf tolerances. http://www.geindustrial.com/publibr...F.pdf&lock=false&attachment=true
What are the other settings.

Update:

We finally convinced GE that the problem must lie with their equipment. A second elevator was installed and it started tripping the main as well (both elevators already had solid-state controls). An engineer with GE FINALLY showed-up, replaced the input board/monitor associated with the main breaker and the problem disappeared. Before the swap, the equipment was getting worse and would trip the main as many as four times a day (it was quite frustrating for all the trades to have the entire building go dark and dead so often). Since GE installed the replacement, the lights have remained on.

Replace the engineer!!!

Run the lift circuit trough a 3phase air coiled inductor to create some more inductance and hopefully smoothen the surge.