Do you have a 50 amp house panel in your RV? If this is correct, then it sounds like you have an open neutral
somewhere, either in the genset itself or the main wiring connection in the house panel. An open neutral in the main wiring will put approximately 240v across any device plugged in downstream.
If you have a 30 amp house panel, then as suggested above you've definitely got a problem with too high of a voltage from the generator.
Either condition will fry a load, even if it isn't turned on. As long as a device is plugged in to an outlet, there are many components inside that are energized whether the device is in use or not.
Here is a link I found to help you determine the exact service you have, and how to troubleshoot the problem:
The first thing I would do is look for the obvious. While disconnected from shore power and with the generator off
, open your house panel and look for anything obvious like loose and/or blackened wires on the bus bars and breakers. Best of luck to you.