Installing EVSE with a Shunt Trip.

I presume the shunt trips when the supply to it is made live, rather than the supply to it being permanently live and it operating as a No-Volt release if the supply is removed?

I presume the shunt trips when the supply to it is made live, rather than the supply to it being permanently live and it operating as a No-Volt release if the supply is removed?

I’ve probably answered my own question, this is the under voltage trip

www.fastlec.co.uk/.../hager-under-voltage-release-230v-ac

yup.
It is just a solenoid in a box that turns the MCB or whatever off for you. Some connect to the front dolly and really do push it off like you would,  other makes link via a spindle or ram-pin  into the side of the breaker body (so for example the newer wylex CBs and RCBOs have a small screw-driver like slot in the side that can be rotated to force a trip even if the dolly is held, while some GE ones have a slot for a ram-pin to move down to do the same.)

There is little standardization sadly.

Coil voltages other than 230 are available for those who like to knock the mains off with 12V dc or whatever.

Also used with things like insulation monitoring and bespoke fault detection kit - say lost phase or off earth detection or something. Useful with power of opportunity, where you may not get the voltages you expected when the local connector is M6 wing nut or croc clips, and a prompt automatic knock off is vital .
Mike