Principle of Operation

REF601 has earth fault protection with low set and high set module.

Earth fault modules operate the protection as soon as fault current exceeds the set value of current.

It supports both DMT and IDMT timing while highset supports to DMT timings.

As the fault current exceeds the set value, trip time counting is started and start LED on front panel of relay glows ON.

If fault current falls down below the drop-off value of set current for 40 ms before trip time gets complete,

start LED will be turned off and trip count will become zero.

Trip time will start from zero next time when the fault current exceeds the set value again.

After a healthy trip, Start LED will be turned off and again

if fault current exceeds threshold, start LED will be turned ON again.

In case of healthy fault generation, after trip time get elapsed relay generates the trip

command which operates the Trip relay contacts as per user selected configuration.

Two LED indications on front plate of relay i.e.

Trip (common trip indication) and Trip Io and one signaling contact (XK2.1 –XK2.2) will

also be generated for user as Trip indication.