In electric motors the objectives of the elements in an electrical panel are to protect the operator and to provide a command logic.
As for operator protection, a sequence of elements required for starting and maneuvering motors are the isolating elements, protection against short-circuit currents, protection against overload currents and switching devices. To understand better, we will describe each item below:
Sectioning: it can only be operated without load and is used during the maintenance and verification of the circuit;
Protection against short-circuit currents: it is the protection of the conductors of the terminal circuit;
Protection against overload currents: protection of motor winding coils;
Maneuvering Devices: refers to turning the engine on and off safely, without any contact of the operator in the power circuit.
The conventional motors are divided in two types, the type 1 coordination, which does not pose a risk to people and installations, with a safe disconnection of the short-circuit current, causing damage to the contactor and the overload relay, and Type 2 coordination which also does not pose a risk to people and installations, but there can be no damage to the overload relay or elsewhere, with the exception of a slight fusion of the contacts.