Overload protectors are one of a single-phase submersible motor’s most important “hidden” components, and play a crucial role in protecting the motor. This issue of Franklin AID will discuss the various types of overloads found in single-phase Franklin Electric submersible motors.
All electrical currents generate heat and under normal operating conditions the heat generated in a motor is easily dissipated into the surrounding water. However, certain conditions can cause the amount of current (amperage) in the motor to exceed the motor’s design limits. Examples include a locked rotor (or locked pump), mechanical drag, and a low or high voltage supply. The heat generated by this excessive current can quickly damage the motor and cause failure. The job of the overload is to protect the motor from failing due to excessive current.
Overload protectors should not be confused with surge arrestors. Surge arrestors are designed to protect the motor from an external voltage surge, such as happens with a nearby lightning strike or an electrical surge on the power grid.
Franklin Electric supplies overloads for all of its single-phase submersible motors. However, depending on the motor design and horsepower, the overloads may be located externally in a control box or internally in the motor itself. Continue reading