Auxiliary Supply Voltage - ABB REU 523 Manual

4
Combined overvoltage and undervoltage
relay
The REU 523 is interfaced with a fibre-optic
bus by means of the bus connection module
RER 103 via the D9S-type RS-485 connector
on the rear panel of the device. The RER 103
enables the use of either the SPA bus or the
IEC 60870-5-103 communication protocol.
The use of the IEC 60870-5-103 protocol
normally requires the fibre-optic star coupler
RER 125.
The optical PC-connector on the front panel
is used to connect the relay to the CAP 501/
505 setting and configuration tools. The front
interface uses the SPA bus protocol. The opti-
cal PC-connector galvanically isolates the PC
from the relay. Since this connector is stan-
dardized for ABB relay products, only one
connecting cable (ABB art. No 1MKC-
950001-1) will be required.
The REU 523 can also be connected to the
Lon bus using a LON-SPA Gateway.

Auxiliary Supply Voltage

The REU 523 requires a secured auxiliary
voltage supply to operate. The internal power
supply of the relay forms the voltages requir-
ed by the relay electronics. The power supply
is a galvanically isolated (flyback-type)
DC/DC converter. When the auxiliary volt-
age is connected, the READY indicator LED
on the front panel will be on.
The primary side of the power supply is pro-
tected with a fuse located on the PCB of the
relay. The fuse size is 3.15 A (slow).
REU 523
1MRS 751123-MBG