Measuring principle

The relay measures the leakage or a short circuit from one or more of the phases to earth.

In order to obtain a short response time on a fault condition, the measurement is based

on peak values.

The earth fault current protection is for example obtained by connecting an external current

transformer in the star point of the protected voltage source.

In order to prevent malfunction due to 3rd harmonic, the RMC-142D is equipped with

a special filter cutting off frequencies higher than 50/60 Hz.

The set point values are set on the front of the relay by means of potentiometers.

If exceeded, a fault signal is generated, and the associated yellow LED is lit.

Timer functions

When the set point is exceeded, its timer starts and will run as long as the fault condition prevails.

If the fault disappears, the timer is reset. When the timer expires, the contact is activated

and the associated red LED is lit.

Relay outputs

The RMC-142D is provided with two outputs with maximum contacts either normally

energised or normally de-energised.

The contact may be set to open or close on activation.

Normally energised contact

Recommended for warning and alarm purposes.

In case of an auxiliary supply dropout, the contact is immediately activated.