Service - ABB REX 521 Technical Reference Manual, General

1MRS 751108-MUM
5.
Protection Relay
Technical Reference Manual, General

Service

When the protection relay is used under the conditions specified in section 4.2.1.
Technical data, it is practically maintenance-free. The relay electronics include no
parts or components subject to abnormal physical or electrical wear under normal
operating conditions.
If the relay fails in operation or if the operating values considerably differ from those
mentioned in the relay specifications, the relay should be overhauled. Contact the
manufacturer or nearest representative of the manufacturer for further information
about checking, overhaul, and recalibration of the relay.
To achieve the best possible operation accuracy, all parts of a REX 521 product have
been calibrated together. Thus, each product forms a whole for which no separate
spare parts can be supplied. In case of malfunction, consult your relay supplier.
The relay sent to the manufacturer has to be carefully packed to
!
prevent further damage to the device.
REX 521
55