TABLE OF CONTENTS Although the aim of this book is to provide the basis to guarantee a suitable relay setting procedure in distribution networks, it is felt that some reference should be made to the installation, testing and maintenance of protection systems. No matter how well the relay applications are carried out, a protection scheme is worthless if its actual performance cannot be guaranteed. It is important to emphasise that a protection scheme covers not only the relays but also the CTs and VTs that feed them, and the circuit breakers that open the circuits on receipt of a trip signal from the relays when a fault occurs.
The installation of protection relays should be carried out following the instructions normally included by manufacturers in their service manuals. The relays are installed on control panels that should preferably be situated in areas free of dust, damp, excessive vibration, and heat. The older types of relays may be set into the panel (flush fitted) or mounted on the face of the panel with a suitable casing. Multifunction relays are generally mounted on standard 19-inch rack cases. The heights of the cases are specified in terms of the number of standard rack units, which typically range from 2 to 5 rack units. The depth of rack mount cases varies depending on the relay model. Some relay models include built-in facilities for testing the relay in the case. Other relay models require external provisions to test the relay in its case.
