User's guide
Generators and motors electrical protection systems

The choice of a protection scheme for alternators or motors must take into account a number of parameters, including :

• the role and importance of the machine within the plant of which it is a part (power generation unit, industrial plant, factory);

• the cost of repair in the event of damage and the costs incurred (e.g. for immobilization of the associated industrial process), or even the cost of replacement with new equipment;

• the compromise between achieving a good level of reliability for the protected machine and the risk of untimely operation (tripping) of a protection, a risk which increases with the number of protection functions implemented.

For example, in certain applications where continuity of service is essential, it may be acceptable to keep a machine showing signs of degradation in service for a limited time,...