Transformer
Generator Fails to Build Rated Voltage
Symptoms
Generator starts and runs normally but output voltage remains low or zero.
Likely Cause
Loss of residual magnetism, faulty AVR, open excitation circuit, or damaged rotor winding.
Testing Procedure
1) Measure output voltage. 2) Check AVR supply. 3) Verify excitation circuit continuity. 4) Inspect brushes and slip rings.
Tools Required
Multimeter, insulation tester, AVR tester
Safety Precautions
Ensure generator is isolated before internal testing.
Step-by-Step Solution
1. Flash the field if residual magnetism is lost. 2. Replace faulty AVR. 3. Repair excitation wiring. 4. Inspect rotor winding.
Prevention
Perform routine AVR testing and terminal inspections.
Engineering Notes
Most voltage build-up failures originate in the excitation system.