By-Passing Circuit Breaker trip- Is this possible

[WiringBoy]

Hi,

This might be more of a controls related question. I have attached a pictures which has two schematic.

1. Existing Schematic
2. Planned Schematic

My Distribution utility shares substation with the transmission utility. Bus protection and bus is owned by transmission utility but our distribution utility owns the feeders and its associated protection.

Existing Schematic shows the main trip that is from the feeder relay and Aux Trip1,Aux Trip 2, 3 & 4 show coming from the transmission utility to trip our breaker directly. These trips could be from Bus diff., bus back up or any other protection scheme. Blocking is shown to block tran.utility trip.

My objective is to determine if transmission utility issued a trip to my breaker, and that is shown in the Planned Schematic. it is like taking + ve and -Ve and then feeding to a digital controller just to detect if a trip was issued from transmission utility.

But I dont want to detect my own trip because my relay would tell me that. Would this work ? Any suggestions please.

 

[WiringBoy]

Thanks Mgrtp for the write up. Actually utility is using RXMH2 relay to trip my breaker. I will be using tripping assembly to be activated by this relay. It has a time delay dial on RXKL Relay to delay contact dropping after deenergigation.

I will have to ask my P&C Staff to use DIN rail arrangement at the back of panel as the front has SEL 351 and FT switches. If they need to be removed that means feeder will be down. My objective is to make sure there is no delay and RXMS1 takes care of it.

Could you please suggest me delay optimum value for RXMH2 contacts to drop out?
These contact rating is 6 amp , hope that is enough.

 

[mgtrp]

If the utility already has an interposing relay, wouldn't you be better off trying to use a spare contact from their relay, or if no spares then replacing their relay with one with more contacts?

 

[WiringBoy]

If that would have been possible then my life would be easy. As you know u bump into some people who don't try to understand logic. That is why I had to do something like this.