+1

My suggestion:

A power supply controls a relay.

Power on = relay's normally open contact.
Power off = relay's normally closed contact, thus bridging the contacts of a T300.

This triggers an alarm and enables automatic functions.

Additional benefit: The T300 has battery monitoring and will notify you when the battery is low.

Surely loss of power has to be an Alert. What about having one on a freezer in a shed!

  @Alphabet 

So use Idea at Post #43 at this time