MPCB = Motor Protection circuit breaker.

MPCB is generally used as Motor circuit breaker for low rating motors. it is a substitute of Thermal overload relay but with advance features.These are Therm o-magnetic type,

     1.Thermal Protection for Overload while Magnetic is for Short circuit protection.Thermal Protection works with a bimetallic strips,The bi-metal strips are heated by the motor current, causing them to bend and activating the trip mechanism after a certain travel which depends on the current-setting of the relay。

     2.Magnetic coil is shaped in the form of a small coil. If a high over current flows through these coils, a force acts on the armature enclosed by the coil. This armature unlocks the loaded switch latch that releases the stored spring energy and hence opens the main contacts and disconnects the over current.

Motor protection circuit breakers are a specialized type of electrical protection device that is designed specifically for electric motors, like their name implies. Electric motors have plenty of applications and are used to drive mechanical devices of all types, so it is very important to protect them adequately with MPCBs. The following are just a few examples of devices driven by electric motors in commercial and industrial buildings:

    1.Rooftop air conditioners, chillers, compressors, heat pumps and cooling towers.

    2.Extraction and injection fans, as well as air handling units.

    3.Water pumping systems.

    4.Elevators and other hoisting devices.

    5.Industrial conveyor belts and other machinery used in manufacturing processes.