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Percentage restraining characteristics
The percentage restraining characteristic is tested on the outflow current (l
out
) and infeed current
(l
in
) plane as shown in Figure 6.5.8. The characteristic shown in Figure 6.5.8 is equivalent to the
one on the differential current (ld) and restraining current (lr) plane shown in Figure 2.11.2.
I
out
DF2
DF1
ik
I
in
0
[kp
･
p2 + (1- p1)ik]/(p2 – p1)
Operating zone
Figure 6.5.8 REF_DIF Element (I
out
- I
in
Plane)
Figure 6.5.9 shows a testing circuit simulating infeed from a neutral circuit and outflow from a
primary winding.
Single-phase
current
source
TB1
DC
voltmeter
-1
-8
-7
-2
TB4
GRT100
-
A
16
-
A
17
Monitoring
j
ack
E
A
0V
DC
power
supply
+
−
+
−
A
φ
Single-phase
current
source
+
−
A
+
−
I
in
I
out
Figure 6.5.9 Testing Restricted Earth Fault Element (Model 100s, 200s)
• Enter a signal number 29 to observe the 1REF_DIF output at monitoring jack A and press the
ENTER
key.