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Function
The sensitive residual current relay module SPCJ
1C7 is a single pole overcurrent module. It
contains two residual overcurrent stages, a low-
set stage I
> and a high-set stage I
0
The low-set or high-set residual current stage
starts if the input energizing current exceeds the
set start value of the stage concerned. When
starting, the stage provides a start signal SS1 or
SS2 and simultaneously the operation indicator
of the stage is lit with yellow colour. If the
overcurrent situation lasts long enough to ex-
ceed the set operate time, the stage that started
also operates and provides a trip signal, TS1 or
TS2. At the same time the operation indicator of
the concerned stage turns red. With switch-
group SG2 the start and operation indicators
can individually be given self-reset or manual
reset mode of operation. If the self-reset mode of
operation is selected, the indicator is auto-
amtically turned off when the stage resets. If the
manual reset mode is selected the indicators are
reset with the RESET push button on the front
panel of the relay module or via the serial port by
means of the command V102 or V101.
The operation of the low-set overcurrent stage
I
> can be blocked by routing a blocking signal
0
BTS1 to the stage. Similarly, the starting of the
high-set current stage I
>> can be blocked by a
0
blocking signal BTS2. The blocking signals are
routed by means of switchgroup SGB on the
PC-board of the relay module.
If the protection relay incorporates an auto-
reclose module, switchgroup SGB is addition-
ally used for the purpose of selecting proper start
signals for the auto-reclose module. The in-
structions for setting the switchgroup are given
in the general description of the protection
relay, in the diagram illustrating the signal inter-
change between the relay modules.
The low-set stage I
> includes three alternative
0
setting ranges, i.e. 0,2...2% x I
5...50% x I
. The setting range to be used is
n
selected with switches SG1/2 and SG1/3. Two
operate time t> setting ranges are available, i.e.
0.05...1.00 s and 0.50...10.0 s. The setting
range to be used is selected with switche SG1/1.
The high-set stage I
native setting ranges, i.e. 1...8% x I
x I
n
>>.
used is selected with switches SG1/6 and SG1/7.
0
Two operate time t>> setting ranges are avail-
able, i.e. 0.05...1.00 s and 0.50...10.0 s. The
setting range to be used is selected with switche
SG1/8. The operation of the high-set stage can
be set out of function by selecting the set value
∞, infinite.
The the two overcurrent stages are provided
with a so called latching facility, which means
that the tripping output remains energized,
although the signal which caused the operation
disappears. The latching function is selected
with switch SG1/4 and the stages are reset by
pressing the push buttons STEP and RESET
simultaneously or with a command V101 tai
V102 vias the SPA-bus.
The energizing input is provided with a lowpass
filter which suppresses harmonics of the ener-
gizing current, see Fig. 1.
dB 10
Fig. 1. Filter characteristics of the energizing
, 1...10% x I
and
input
n
n
>> also includes three alter-
0
and 25...200% x I
. The setting range to be
n
0
-10
-20
-30
-40
-50
-60
0
1
2
3
4
, 5...40%
n
5
6
7
f / f n
3
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