Generator AVR mechanical and electrical faults and solutions

Generator AVR failure is generally divided into AVR mechanical failure and AVR electrical failure, users often encounter various types of failure in the use of the process do not know how to deal with or troubleshooting, the following partsofgenerator as a generator AVR manufacturers specially compiled a detailed generator AVR mechanical \ electrical failure and solution measures table as follows.

    1. AVR mechanical failure and solutions




The bearing temperature is 50 °C higher than the ambient temperature .

Abnormal noises appear or do not appear. 

– If the bearing turns blue or the grease turns black, replace the bearing.

One end is not aligned. 

abnormal temperature 

The generator frame is overheated (40 °C above ambient temperature ). 

One air passage is blocked or hot air is repeatedly circulated to remove air passage obstructions

1. The operating temperature of the generator is too high (more than 05% of the rated voltage when the load is on)


A generator is overloaded. 


Vibration is very loud 

1. There is no alignment (coupling), or the combination with the prime mover is not qualified.

Unqualified rotor balance (prime mover and generator) 

There is obvious vibration and there is obvious noise in the motor

A phase imbalance.

Stator short circuit. 


The generator was significantly damaged, followed by rattling and vibration. 

A system short circuit.

A car error.

Possible results:

A coupling is broken or damaged.

A shaft end is broken or damaged.

A rotor is deformed or shorted.

A fan is cracked or loose on the shaft.

There is irreparable damage to a pair of spinning diodes or AVRs. 

    2. AVR electrical faults and solutions





There is no no-load voltage when starting. 

Terminals F+ and F- are disconnected from AVR and then connected

4~12V new battery, last 2 to 3 seconds.

Pay attention to the polarity of the battery and terminals F+, F-


When the battery is removed, the voltage is established and correct. 

A loss of magnetism. 


When the battery is removed, the voltage builds up but does not reach the rated value

– Check the connection of the AVR reference signal line

– Diode failure

– Short circuit of field armature.

voltage is too low 

Check the speed

correct speed

– Check the AVR wiring (maybe the AVR has failed).

– Short circuit of the field winding.

– The rotating diode burns out.

– Main rotor winding open circuit (check resistance)


RPM too low

-Increase the speed (to the correct value, then adjust the voltage setting of the AVR)

voltage is too high 

Adjust AVR Voltage Potentiometer 

Adjustment is invalid. 

_Check AVR wiring (maybe AVR failed) fault.

-AVR failure 

voltage oscillation 

Adjust the AVR steady state potentiometer 

If no effect: try increasing or decreasing stabilization

1 Check the rotational speed: it may be aperiodic oscillation.


A loose connector connection on an AVR.


An AVR failure.


Speed is too low (or LAM setting is too high) at a load 

Correct voltage at no load, load

Run with no load, check the voltage between F+ and F- on the AVR. 

DC voltage between F+ and F-<10V 

1 Check the RPM (or the F/V setting is too high) 

voltage is too low. 

DC voltage between F+ and F->15V 

– Rotating diode failure

– Main rotor short circuit, check resistance

– Exciter armature, check resistance

The voltage disappears during operation. 

Check AVRs, Varistors, Rotary Diodes

Voltage will not return to rated value. 

An exciter field winding is open.

An exciter rotor failure.

An AVR failure.

A main rotor is open or shorted. 

tube, and replace any failed parts. 

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