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TB XRI1-IR 02.00 E
23
7.4.2
Test circuit of
XRI1-IR
Figure 7.1: Test circuit
For testing relays with directional feature, current and
voltage input signals with adjustable phase shifting are
required. Figure 7.1 shows an example of a single
phase test circuit with adjustable voltage and current
energizing the
XRI1-IR
relay under test.
For testing a relay with directional feature, one of the
input energizing quantity (voltage) shall be applied to
the relay with a constant value within its effective
range. The other input energizing quantity (current) and
phase angle shall be appropriately varied.
XRI1-IR
is a three phase directional time overcurrent re-
lay with relay connection angle of 90°. That is why
the phase angle between input current and input volt-
age has to be set to -90° before the measuring proce-
dure is started. The relay input currents and their corre-
sponding reference voltages are shown in table 7.1
(refer to Fig. 4.2):
If the single phase test circuit as illustrated in
Figure 7.1 is applied to test the directional feature of
the relay and the current source is connected to
phase 1 current input (1S1/1S2), then the voltage
source should be connected to relay terminals L2/L3.
In order to test the directional feature, parameters have
to be set in compliance with table 7.2. Then a test vol-
tage equivalent to the rated voltage is connected to
terminals L2/L3 and a current of 1 x In is impressed
upon the current inputs 1S1/1S3.
It is now possible to read and check all measured va-
lues in accordance with Table 7.1. If the phase posi-
tion is changed, the values I
Q
and I
P
change. If the an-
gle is changed by 90
o
, for example, the measured va-
lue for current input I1 must be ±0 for I
P
and +1.0 for
I
Q
.
Determining the change in direction
The angle of greatest sensitivity for determining the
phase direction is adjustable between 15
o
and 83
o
.
Consequently, the greatest sensitivity is achieved with
setting 49
o
if the input current leads the input voltage
by 49
o
. This setting results in a tripping range in fore-
ward direction of 139
o
leading to 41
o
lagging if the
marginal regions are neglected on account of lack in
measuring precision.