Several common issues with power systems of which surges are both the most common and the least troublesome.
One is a mis-wired park. Open ground or open neutral and the better protectors like the Progressive Industries HW-50C or their new portable model (Replaced the PT-50C) will detect and protect
Many parks have low voltage which is very hard on Air conditioners and some other stuff the units I mentioned will detect and protect
I've heard way too many stories of someone plugging into an 30 amp outlet with an adapter "Oh people use that all the time" only it is a 240 volt outlet and they fry everything in the RV .. It will detect and protect.
And finally I've seen many what I call "Power blinks" Where power goes out for just one or 2 seconds and comes right back on, again hard on the A/C. these units hold power off for over 2 minutes. To Protect.
Southwire/TRC Surge guard makes a unit that is not much different from the Progressive Industries.. I don't have the model number handy but the key is these area all top of the line units.
Both companies also make smaller, cheaper, units that ONLY protect against power spikes. no over/under voltage or other protection.