Ambient Temperature Compensated Bimetallic
Ambient-compensated bimetallic overload relays are designed for one
particular situation; that is, when the motor is at a constant ambient
temperature and the controller is located separately in a varying ambient
temperature. In this case, if a standard thermal overload relay were used, it
would not trip at the same level of motor current if the controller temperature
changed. The standard thermal overload relay is always affected by the
surrounding temperature. To compensate for temperature variations, an
ambient-compensated overload relay is used. Its trip point is not affected by
temperature, and it performs consistently at the same value of current.
Thermal Overload Relay Trip Characteristics
Melting alloy and bimetallic overload relays are designed to approximate the
heat actually generated in the motor. As the motor temperature increases, so
does the temperature of the thermal unit. The motor and relay heating curves
(left) show this relationship. From this graph we can see that no matter how
high the current drawn, the overload relay will provide protection yet will not
trip unnecessarily.
Solid State Overload Relay
There are some substantial advantages to using the solid state electronic
device. The device does not require thermal units. The customer does not
have to exercise skill at the selection procedure nor is there a need to stock
Shipping Port: Xiamen, China
