The bimetallic materials are Invar and brass. These materials having the differential coefficient of expansion. All bimetallic relays incorporate additional built-in single phasing protection.
The range of the relay provided for the feeders are such that the full load rating of the feeders is comfortably within the range of the relay (range will be at Centre) except in very minimum loads ranging from 0.1 – 0.16 A.
