First there are surge protectors and SURGE PROTECTURS. You need to know the difference.
The first, is not unlike the little six outlet "Surge Supressor" strips you get all over the place. Many plug therir computer and cable modem and printer and such into them (myself included) They make 30 and 50 amp units as well. These are really spike supressors. Though they do provide limited protection against ONE power line issue (Spikes) they are no good against surges (Sustained high voltage) or brownouts (Sustained LOW voltage). or any other fault.
Now there are some in teh 200-500 dolllar range, These include the Progressive Industries PT-30c and HW-30c
These contain replacable SPIKE supressors.. (THe low cost stuff) and in addition they monitor voltage and frequency.
If any of those goes high, or low, they cut you off to protect you.
I"ve seen parks where the outlet voltage drops below 90, voltages this low will affect your air conditioners and possibly some other stuff.
I've seen high voltages as well, this bothers your electronics and may take out heaters (Fridge and water water)
And in teh case of a 30 amp plug.. Well there is a common 240 volt outlet that it will fit in just fine, and many are the electricians that look at a TT-30 outlet and ASSUME (you do remember how to spell that right) and wire it for 240 volts (it is supposed to be 120)
THe expensive units, with LCD displays that show voltage and current (EIther local or remote) .. Well they will say 240 volts, do not bypass Or some such.. and nothing bad happens
The cheap ones simply blow up (internally, not dangerous) and let your hardware fry.