AVR circuit is composed of rectifier main circuit, voltage detection circuit and comparison and control circuit; excluding the possibility that the damage is caused by the quality problems of the electric components, the working frequency of the main circuit and comparison and control circuit changes most among the whole AVR circuit. And the rectifier bridge in the main circuit and the transistor in the comparison circuit change even more frequently, and their damage proportion accounts for more than 90% of the whole AVR damage rate. AVR is non-dismantle components, and if it is damaged, it needs to be replaced. Therefore, we mainly analyze the reason that causes the damage of AVR in the generator and to avoid AVR damage as much as possible is the most important. 
 
The service life of AVR can be increased if it is used properly. 
(1)If the voltage of the engine is more stable, the change in AVR is less frequent; if the switch motion of transistor in comparison circuit is gentler, the AVR damage probability rate is less;
(2) If the output load is relatively stable, the change in AVR is less frequent, and if the switch motion of transistor in comparison circuit is gentler, the AVR damage probability rate is less;
(3)If the rotational speed of the engine is more stable, the oscillatory surge that currency variance causes to AVR is less; 
(4)Frequent “idle running”, overload running and great difference of load are the main causes of AVR damage.