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6.5.1.2 2F element
The testing circuit is shown in Figure 6.5.5.
Current
source
TB1
DC
voltmeter
TB4
-1
-2
-
A
16
-
A
17
GRT100
DC
power
supply
+
−
Monitoring
j
ack
A
0V
+
−
+
−
Current
source
50 or 60Hz
100 or 120Hz
+
−
I
a
I
1
I
2
Figure 6.5.5 Testing 2F Element (Model 100s, 200s)
The output signal number of the 2F element is as follows:
Element Signal number
2F 122
• Set the second harmonic restraint setting k2f to 15%(= default setting).
• Press 4 (= Logic circuit) on the "Test" sub-menu screen to display the "Logic circuit"
screen.
• Enter a signal number to observe the 2F output at monitoring jack A and press the
ENTER
key.
• Set the fundamental frequency current I
1
to 3 times of ik setting. Change the magnitude of
the second harmonic current I
2
and measure the value at which the element operates.
• Calculate the percentage of the second harmonic by I
2
/I
1
when the element operates.
Check that the percentage is within 7% of the k2f setting.