EES-014 outlines the requirements for electrical protection on the Generator.
Section 4.4 covers 3 phase generators with TN (MEN Link) earthing, and has the following requirements
- Main Breaker to operate in all active conductors (active and neutral)
- Core Balance Earth Leakage to trip the Circuit Breaker via undervolt coil.
- Back Up Earth Leakage (MEN link toroid) to trip the CB via shunt trip coil and shutdown the engine. The picture in EES-014 shows a separate trip operator for backup earth leakge, which is possible in C60 miniature CBs.
- EES-014 specifies a failsafe method of tripping the Main CB (ie an undervolt coil). In most cases, this cause operational issues as the Main CB will trip every time the generator stops. This means that automatic operation is impossible, and a competent person must reset the Main CB every time the generator is started. Depending on your “Restoration of Power” procedures, this may mean that an electrician is required to start a geneator, since the CB will be in the tripped position, and no-one will know for sure if it was a legitimate protective trip or a shutdown trip.
- Subcircuit protection to operate in both active and neutral (2pole RCBOs for single phase, and 3pole CB with 4pole RCD or 4pole CB with earth leakage relay for 3phase circuits)
- Equipotential bonding
- Earth Stakes are optional, but not recommended.