What is the use of Varistor in Alternator's? Will it be used to protect Rotating Rectifier diodes or Main Rotor winding in Alternator?

Hello Mapj1,

Varistor connected in parallel across the DC supply which is the output of Rotating rectifire diodes.For details refer the attached AVK alternator drawing. 

Alternator is 2660 KVA which is installed in Power plant.  

I checked varistor normally its showing open circuit. 

Just want know will it protect,                                     

1. Rotating rectifire diodes 

2. Main Rotor windings. 

from which kind of fault it will protect generator. 


AVK Generator.jpg

Hello Mapj1,

Varistor connected in parallel across the DC supply which is the output of Rotating rectifire diodes.For details refer the attached AVK alternator drawing. 

Alternator is 2660 KVA which is installed in Power plant.  

I checked varistor normally its showing open circuit. 

Just want know will it protect,                                     

1. Rotating rectifire diodes 

2. Main Rotor windings. 

from which kind of fault it will protect generator. 


AVK Generator.jpg