ABB REX 521 Technical Reference Manual, Standard Configurations Download

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1MRS751802-MUM

Protection Relay

Technical Reference Manual, Standard Configurations

REX 521

10.2.5.3.

Outgoing blocking signal to the overcurrent relay on the HV side

The start signals from the overcurrent protection function can be routed to an output
relay to provide a blocking signal. The overcurrent stages 3I>> and 3I>>> have also
a separate BSOUT signal for blocking purpose.

As mentioned above, the start signal from the first high-set overcurrent stage 3I>>
can be routed to the first high-set stage 3I>> of the HV relay. To use the start signal
from a protection function the signal has to be routed via

Main menu\Configuration\Output SWGRP\Start 1

\Start 2

When the start signal has been routed, the output relay has to be selected in

Main menu\Configuration\Output Signals

. In this example, the

overcurrent start signal from the 3I>> stage is routed via Start 1 and then connected
to the signal output 1, SO1. The checksum in this application example for Start 1
is 2.

10.2.5.4.

Trip signal from second residual voltage stage

The trip signal from the residual voltage high stage can be routed to an output relay
to provide a back-up trip signal to the outgoing feeders of the network.

To use the trip signal from the residual voltage protection function, the signal has to
be routed via the

Main menu\Configuration\Output SWGRP\Trip 2

or \Trip 3

. When the trip signal has been routed, the output relay has to be

selected in

Main menu\Configuration\Output Signals

In this example, the directional earth fault stage Io>>-> is configured as a Uo>>
protection and is routed via Trip 2 and then connected to the power output 2, PO2.
The checksum in this application example for Trip 2 is16.

Note also that the events (for example start and trip) for the residual overvoltage
protection will be sent from the directional earth fault stages.

10.2.5.5.

Second settings for residual voltage protection

If an external control signal determined from the earthing situation of the network is
available, it can be used for changing to the second settings of the residual voltage
protection. The usage of different settings can be useful when switching between a
compensated network and an isolated network which results in changes in the level
of the neutral voltage during earth fault.

In this example, the digital input DI5 is connected to the input signal Group and then
routed to the group input of the directional earth fault functions, which in this
example is configured as residual protection. The Group signal can be found in

Main menu\Configuration\Input Signals\GROUP\

where DI5 is

selected. The checksum for the switchgroup in

Main menu\Configuration\Input SWGRP\GROUP\

should be 2 to

change to the second settings for earth fault. In the control settings for the directional
earth fault functions, the group input has to be chosen for the group selection. Refer
to the CD-ROM

Technical Descriptions of Functions

(see Section 1.5. Related

documents) for more information about the directional earth fault function.