CH DigiTrip RMS 520 ZSI
CH DigiTrip RMS 520 ZSI
(OP)
New here to the forum. I have a project to implement Zone Selective Interlock (ZSI) on a 480V bus (Y-connected) system using CH Digitrip RMS 520 LSIG. I will like to disable the "ground fault" function on the main breaker and some feeder breakers feeding the MCC and large motor downstream. We have experienced spurious ground trips in the past on this bus each time a piece of equipment is been put back in service. Has anyone have success doing this without any detrimental effect on the equipment? Any help is highly appreciated.






RE: CH DigiTrip RMS 520 ZSI
Generally, nuisance GF trips can be reduced by increasing the time delay.
David Castor
www.cvoes.com
RE: CH DigiTrip RMS 520 ZSI
Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.
RE: CH DigiTrip RMS 520 ZSI
With ZSI on, the downstream breaker defaults to minimum TD or INST (no intentional time delay). This may be the cause of some of your nuisance trips. A device with a ground fault would not always coordinate with the downstream breakers without GF.
Also have someone experienced look at the coordination.
Rafiq Bulsara
http://www.srengineersct.com
RE: CH DigiTrip RMS 520 ZSI