How the Watchdog relay of P122 works.

The watchdog output is changeover contact, NO will become NC after powering up & healthy
The normally closed (NC) contact of the Watchdog (RL0) cannot be configured.

In power Off condition 35-36 is closed; 36-37 is open.
Once the relay is powered up, the RL0 relay is energized i.e. 36-37 is closed; 35-36 is Open & this is a healthy condition.

Major fault:
The protection and automation functions are stopped.
The RL0 watchdog relay is de-energized (35-36 contact closed).

Minor fault:
The MiCOM relay is fully operational.
The RL0 watchdog relay is energized (35-36 contact open, 36-37 contact closed).

Released for:Schneider Electric India