Disconnection Relay G83 - Embedded Generator

[simma]

I understand that a disconnection relay must disconnect in the event of mains supply failure, however by what means does it achieve this?

If a sterling engine type generator is connected into a final circuit, what is the disconnection relay monitoring to register the mains failure? If anyone knows of any literature, or diagrams which may be of help with this I would like to know.

 

[Gavin A]

would I be right in thinking this refers to a micro CHP boiler?

I don't know the exact process, but it must monitor the grid voltage / frequency then cut out via a contactor within 5 seconds when the grid goes off - at which point the voltage and frequency on the remaining circuits will have plummeted as the SSEG is effectively trying to power everything connected to the islanded grid at that point, which it obviously can't do.

 

[BruceB]

A way of doing it is frequency monitoring. The inverter when synchronised is always trying to push the frequency in one directorion, say up. So if the frequency starts increasing it knows it must be disconnected from the grid and cuts off. They also monitor voltage as Gavin describes and sometimes circuit impedance as well. Google SMA Grid Guard will pull up some articles on it by one manufacturer.