Fault and Protection of Alternator

The alternator is a very essential device for an industry or plant. That’s why its protection is also essential. But alternator protection is more complex.

Why is alternator protection very much complex?

• The alternator produces very high ac voltage and it is connected to bus bars.
• Various other equipment is always associated with alternators. Such equipment is a prime mover, excitation system, voltage regulator, and cooling system. Thus equipment protection is also considered when alternator protection.
• The alternator is a very expensive and very important factor in the power system.

Faults of Alternator

Three types of fault may generate in an alternator. They are-

1. Abnormal running condition.
2. Rotor faults.
3. Stator faults.

Alternator Abnormal Running Condition

The alternator's abnormal running condition may occur due to-

1. Failure of the prime mover
2. Loss of excitation (Failure of field).
3. Overcurrent (Overloading)
4. Over speed.
5. Overvoltage.
6. Unbalanced loading.

Rotor Fault

Alternator atator may affect by these types of fault given below

1. The conductor to earth fault
2. Short circuit between the turns of the field winding

Stator Fault

Alternator rotor may affect by these types of fault given below

1. Insulation failure
2. Fault between phase and ground
3. Fault between phases
4. Inter-turn fault involving turns of the same phase winding

We will try to explain these fault condition and their estimated solution in the next content.

Written
Jeion Ahmed