Fault X on relay SEL501 1

[SA07]

Hi

We are a power plant exporting power on the utility network. Following a fault on the network, we islanded. We have a SEL311, SEL387 and SEL501 relays. SEL 501 is a back up relay.
SEL311 or SEL387 did not tripped. We had message “Fault X” on SEL 501.
From our fault recorder, we see that our plant islanded first and then sent an inter trip to the utility station to open their breaker.
Does Fault X on relay SEL501 means the relay has tripped? We do not find any other cause of the islanding.
We will connect with the SEL501 in a few days after a shutdown to retrieve the fault history.

 

[davidbeach]

The SEL-501 is two very basic overcurrent relays in a single package, the X relay and the Y relay. Fault X simply means that the X relay saw something. Depending on the settings you can get the fault indication without a trip.

Beyond that it would take drawings, settings, and event records to begin to know what might have happened.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[stevenal]

We do not find any other cause of the islanding.

Seems simple enough. Fault on utility network causes utility to trip, leaving plant islanded until next action.