CT1M Multiplier accessory
CT1M: It’s a multiplier for the current setting of those ELR’s up to 250 A. It’s placed between the ELR and the measuring CT (It isn’t passing through wire).
EARTH LEAKAGE RELAYS APPLICATION WITH CT’s
*The setting of the relay connected with the CT1M is multiplied for 10. Please consider this change in the front of the relay.
When there is no earth leakage, the vectorial addition of the currents sensed by the CT’s, is equal to zero. Thence, there is no current flowing in the windings related to our terminals 5 and 6 (in our special toroid). There isn’t any voltage generated in our terminals 1 and 2, therefore, which should make the ELR to trip.
When there is a leakage, otherwise, the vectorial addition of the currents sensed by the CT’s is different to zero. Thence, a voltage is generated through the terminals 1 and 2, which will make the ELR to trip. For this application, it is advisable to have a tripping threshold of the ELR, not lower than a 1/100 of the rated current of the system to be protected.