On running 125 KVA Swan DG set, there is a problem of no output voltage. The alternator has no other electronic components other than diodes and AVR. I changed the AVR available in the market which can be used for upto 500 KVA alternator. On running the DG set, I got the rated output voltage of about 230V per phase at no load.The DC voltage at AVR terminal F+ and F- gives about 12 V at no load.
But,as the 3-phase welding machine is tried to run,the voltage as shown in the voltmeter drops and fluctuates and the machine does not turn on. While trying to turn on a grinder,the grinder produces a noise and stops.
This shows that the load is unable to draw current from the alternator.
Three different AVRs have been changed but the result is the same.One of the AVRs is attached herewith.
So, what might be the problem? Is any faulty in field winding or other windings can cause such problem? Or, any problem in excitation can cause such problem?
Why the alternator cannot deliver current though it gives rated output voltage.
