What is the purpose of heaters installed in motor starters?

The purpose of heaters installed in motor starters is primarily to provide overload protection for the motor as well as to contribute to the protection of branch circuit conductors. When a motor experiences an overload condition, the increased current flow heats the heater elements, which are designed to trip the starter and disconnect the motor from the power supply. This mechanism helps prevent damage to the motor itself due to excessive current.

In addition to this critical function, heaters also serve to protect the branch circuit conductors indirectly. By tripping during overload conditions, the heaters help avoid excessive current that could lead to overheating of the conductors and potential fire hazards. Therefore, the heaters play a dual role by ensuring both the motor and the wiring remain safe during varied operating conditions. This comprehensive protection is crucial for maintaining the integrity and longevity of both the motor and the electrical system as a whole.