1. Protection systems and plans

1.1 The need for back-up

Correct elimination of a fault requires protection of the structure concerned:

• capable, by its principle, of correctly identifying the fault ;

• in working order.

• The first criterion involves the protection's intrinsic ability to detect and correctly locate a fault.

  It should be remembered that the behavior of a protection device in the presence of a fault is the result of compromises that have necessarily been made during its design: measurement principles, organization of processing and decision logic, etc. It is therefore impossible to guarantee that a given protection device will operate correctly...