Selection and ordering data

The relay type and serial number label identifies the protection

relay. The label is placed above the local HMI on the upper part

of the plug-in-unit. An order code label is placed on the side of

the plug-in unit as well as inside the case. The order code

consists of a string of letters and digits generated from the

relay’s hardware and software modules.

Relay case and plug-in unit

The relay cases are assigned to a certain type of plug-in unit.

For safety reasons, the relay cases for current measuring relays

are provided with automatically operating contacts for short

circuiting the CT secondary circuits when a relay unit is

withdrawn from its case. The relay case is further provided with

a mechanical coding system preventing the current measuring

relay units from being inserted into relay cases intended for

voltage measuring relay units.