In the control of the electric motors are three main functions: the starting, the mechanical protection and the electrical protection.
Starting – An engine will only start to rotate when the moment of loading to be stopped, when stopped, is less than its starting torque.
Mechanical protection – Engines must be protected both to protect service personnel and against harmful external influences to the engine itself, and must meet established safety, accident and fire prevention requirements. The motor housing serves to secure it to the workplace and protect it depending on the environment in which it will be installed. The carcass is made in such a way as to combine the different modalities of mechanical protection to satisfy the requirements of the regulations regarding the installations and machines for which the engines will be designed. https://www.mrosupply.com/bearings/cam-track-follower/2490392_sfh-40-a_carter/
Basically, the mechanical protections are classified into three categories: drip and splash proof, fully enclosed and explosion proof.
Electrical Protection – Since all motor is subject to variations from the electrical point of view, it is convenient to have protection for this. In general, the necessary protections are against short circuit, overload, low voltage, open phase, phase reversal, internal defects etc.
The protective devices actuate the shutdown mechanisms in case of a predetermined condition.