A Generator is the most important and costly equipment in a power system. As it is accompanied by Prime mover, Excitation system, Voltage regulator, Cooling system, etc., its protection becomes very complex and elaborate. It is subjected to more types of troubles than any other equipment.
A modern generating set is generally provided with the following protective schemes:
(i) Stator Protection
Percentage differential protection
Protection against stator inter-turn faults
Stator overheating protection
(ii) Rotor Protection
Field ground-fault protection
Loss of excitation protection
Protection against rotor overheating
(due to unbalanced three phase stator currents)
(iii) Miscellaneous
Over voltage protection
Over speed protection
Protection against motoring
Protection against vibration
Bearing-overheating protection
Protection against auxiliary failure
Protection against voltage regulator failure
[You can concern to internet for connection diagrams and details of each protection scheme]