AVR Changing with Different Type

Can you post the wiring schematic diagrams from the old and new unit? What is the model number of the generator ?

Assuming that the rating of the inputs and outputs are compatible you should have a normally functioning self-excited generator. What you won't have is the benefit that a separately-excited generator offers, namely voltage support during system transients such as starting large loads or during short circuit conditions. Under these circumstances the power source for your AVR and consequently the field excitation, namely the terminal voltage of your generator, will be subject to the same dips and swings that the generator experiences. And what is the generator terminal voltage during a close in fault- zero- meaning that the AVR cannot provide any field current.

So now you know what the advantage of a separately powered excitation system is, that the PMG provides excitation power regardless what the terminal voltage is doing. Only you know if that's important to the proper operation of your system.

thankyou all
I have replaced the avr and it is working well.
best regards