The action principle of thermal relay and electrical diagram is introduced

Thermal relay is a protective appliances using the heating effect of the current work. Thermal relay by heating element ( Resistance wire) , bimetallic strip, transmission parts and the normally closed contact, when the motor overload, through the heating elements in the thermal relay current is added, the bimetallic strip heated bending, drive the normally closed contact. Thermal relay is often used in motor overload protection for a long time. When the motor overload for a long time, thermal relay the normally closed contact of action, disconnect the corresponding circuit, the motor are protected. As a result of the bimetallic strip thermal inertia, namely cannot respond rapidly to short-circuit current, and the thermal inertia is required, because the motor starting or short time overload, thermal relay not action, to avoid the unnecessary parking of motor.