P643- DISC CT Invalid Alarm & event

[Rajasekhar_A_CRC_Operations_lead]

Dear Team

In one of the P643 relay, there is this alarm called DISC CT Invalid which is triggered ON & alarm is continuously getting generated.  This alarm is blocking the protection functions of the relay from working properly. What is the source of this error. Is it because of HW failure (CT-VT module ) in the relay or a SW failure. And what could be the reasons for the same,

Please advise.

[Rajasekhar_A_CRC_Operations_lead]

Team,

We could able to resolve this issue by following the below steps. Understood that relay does not automatically reset certain internal states, including this specific alarm. 

1. Removed the battery from the relay.
2. Powered off the relay completely.
3. Waited a few moments 
4. Powered on the relay.
5. Re-inserted the battery.

DISC CT invalid alarm is resetted.

But what could have been triggered this alarm. Is there any specific reason for this. As far as site condition is concerned, the relay has been purchased some time ago & it was powered on for commissioning recently. Immediately after power on- we observed this alarm

Thanks

Rajasekhar.

[Gregory_Meunier · Accepted solution]

Hi Rajasekhar,

The alarm is related to the CT input exclusion logic.
It happens when after a power cycle the excluded CTs are different than before.
To remove the alarm, it is needed to power cycle the relay with the battery  removed.