why generator are designed for p.f = 0.8 or 0.85? if generator is running at 0.9 to 0.97 p.f continuously then what problem will arises? pls give me details.

 

The generator power factor design limit is a MINIMUM limit, not a maximum. The generator you describe will be quite happy to run at 0.9 or higher power factor. It will be unhappy at 0.75 power factor.