What is the minimum number of poles required in a 3-phase magnetic starter?

To understand the minimum number of poles required in a 3-phase magnetic starter, it is essential to recognize the function of a magnetic starter and the nature of three-phase electrical systems.

A magnetic starter is designed to control the operation of a three-phase motor by providing start and stop control, as well as overload protection. In three-phase systems, each phase must be managed to ensure balanced and effective operation.

For a magnetic starter, using a minimum of four poles is necessary. This includes three poles for the three phases (one for each phase: A, B, and C) and an additional pole typically used for the motor's overload relay. The overload relay is crucial for protecting the motor from damaging current surges by disconnecting the supply if the current exceeds a predetermined threshold.

Thus, the correct minimum requirement is four poles for a 3-phase magnetic starter, accommodating each phase and providing essential safety features.