6
The energizing currents of the overcurrent unit
are connected to terminals 1-2, 4-5 and 7-8,
when the rated current of the CT secondary
circuits is I
n
= 5 A. When the rated current of the
CT secondary circuits is I
n
= 1 A, terminals 1-3,
4-6 and 7-9 are used. The relay can also be used
in single-phase or two-phase applications sim-
ply by leaving one or two energizing inputs
unoccupied. In single-phase applications the
same energizing current can be routed through
two energizing inputs, which may increase the
operating speed of the overcurrent unit, espe-
cially at instantaneous operation.
The energizing current for the earth-fault unit is
connected to terminals 25-26 when the rated
current I
n
= 5 A and to terminals 25-27 when
the rated current I
n
= 1 A.
The control input 10-11 can be used in three
different ways, i) as control input for an external
blocking signal, ii) as the control input for
unlatching the trip relay, or iii) as the control
input for the remote control of relay settings.
The requested function is selected by means of
switches switchgroup SGB in the main menu of
the protection relay module.
The auxiliary supply voltage of the relay is
connected to terminals 61-62. At d.c. supply
the positive lead is connected to terminal 61.
The level of the voltage to be applied to the
terminals depends on the type of power supply
and output relay module inserted in the relay.
For further details see the description of the
power supply module. The permitted auxiliary
voltage range of the relay is marked on the relay
front panel.
Output relay A is a heavy-duty trip relay capable
of controlling most circuit breakers. The oper-
ate signals of the different protection stages are
routed to the trip relay with switches 2,4,6 and
8 of switchgroup SGR1. On delivery from the
factory all the protection stages are routed to the
trip relay. A latching of the output relay A can
be selected with switches 6 and 7 of switchgroup
SGB.
Output relays B and C can be used for signalling
on operation of the relay module. The signals to
be routed to the output relays B and C are
selected with switches1...8 of switchgroup SGR2.
The switch matrixes for routing operate signals
to the output relays B and C are identical.
Normally output relay B is used for signalling on
operation of the overcurrent unit and C for
signalling on operation of the earth-fault unit.
This is also the default setting of the relay on
delivery from the factory.
The start signals of the protection stages of the
relay are routed to output relay D. The signals to
be routed to output relay D are selected by
means of switches 1, 3, 5 and 7 of switchgroup
SGR1, which is a software switchgroup found in
the main menu of the protection relay module.
The start signals of the low-set and high-set stage
of the overcurrent unit are selected with switches
1 and 3, and the start signals of the high-set and
low-set stage of the earth-fault unit with switches
5 and 7.
The output relay E is a heavy-duty relay as
output relay A. It can be controlled by the start
and operate signals of the protection stages.
Output relay E is also used a trip relay for the
circuit breaker failure protection (CBFP), when
the CBFP protection is used. In this case the trip
signal can be used either to control a circuit
breaker upstreams or to control a second trip
coil on the main circuit breaker to increase the
redundancy of the circuit breaker.
Output relay F functions as output relay for the
self-supervision system of the protection relay.
The F relay is energized under normal operating
conditions and contact gap 70-72 is closed. If a
fault is detected by the self-supervision system,
or on loss of auxiliary supply, the output relay
drops off and the NO contact 71-72 closes.
By means of bus connection modules type
SPA -ZC17 and SPA-ZC21 the relay connects
to the fibre-optic SPA bus via a 9-pole, D-type
subminiature connector located at the rear panel
of the relay. The terminals of the fibre-optic
cables are connected to the counter terminals Rx
(receiver) and Tx (transmitter) of the bus con-
nection module. The fibre-optic cables are linked
from one relay to another and to the substation
level communication unit, for instance type
SRIO 1000M.
