Almost, but no cigar. =D>
A relay cant operate without voltage.
Just in case you dont know how it works...
While there is electricity the switch keeps the internal relay energised, allowing the machine to work. In the event of a power failure, the relay inside the switch drops out, disconnecting the machine from the mains, and has to be manually reset after power is restored.
This is to stop the machine starting up by itself when power comes back on.