[flybouy]

^^^ what he said. an EMS (energy management system) will monitor the incoming power. If there is an issue such as missing a connection to ground, or neutral, or excessively low voltage, it will shut the power off to protect the appliances from incurring damage. The a/c units, fridge, water heater, etc. can be damaged from brown outs (low voltage) and from power cycling (like your lights at home flickering during a bad storm) by disconnecting the power and not restoring it until the power is stable. Then when it is stable it will have a delay before energizing to protect the a/c compressor.

Don't confuse an EMS with a surge protector. Surge protectors are useless.