[Richard and Rhonda]

I am no electrical engineer, but I and many others on this site can answer the questions. So here's a laymans explanation.

One, in any live circuit when the voltage drops the amperage goes up. Ohm's law. More amperage generates a lot more heat, hence low voltage burns up motors since the windings and other motor innards are not designed to handle the heat.

Also when the voltage drops, the hertz or frequency does not change from a practical standpoint. If the power is coming from the national grid it will be 60 Hz. If it is coming from a private generator like your coach the frequency can be off.

If you are at a campground that is dropping to 90 volts you are going to burn up a lot of expensive electrical components.

Suggest you search on this site and others for voltage protection devices.