I have a problem in my generator is the fluctuating they 10 to 15 volts. How can I solve the problem please help mi.what is the cost of the problem

I have a problem in my generator is the fluctuating
they 10 to 15 volts. How can I solve the problem please help mi.what is the cost
of the problem

How can we even guess what it costs if we don't knowing exactly what's wrong, what kind of generator it is or where it is?

Not to mention that the heading does not even begin to match the question.

1000KVA is a big commercial generator. You should have it looked at by the manufacturer. This is not a DIY question as the voltage and amperage can cause serious injury or death if you don't know what you are doing..