13.45
Date Code 20060320 Instruction Manual SEL-311C Relay
Testing and Troubleshooting
Test Procedures
Equation 13.60
Taking the test signals from Table 13.6.
V
A
= 40.4 V ∠0°
V
B
= 67.0 V ∠–120°
V
C
= 67.0 V ∠120°
Equation 13.61
I
A
= 2.5 ∠ –82.42°
I
B
= 0.0 ∠0.0°
I
C
= 0.0 ∠0.0°
Equation 13.62
Using Equation 13.58 to calculate Z2, we obtain the following
result:
Equation 13.63
The relay example Z2F setting is 0.77 Ω. The value of Z2c
applied (–10.66 Ω) is less than the Z2FT threshold (–2.91 Ω),
so the 32GF element asserts when these signals are applied. If
Z2c applied is greater than the Z2FT threshold, select new test
current and voltages through performance of the steps outlined
above.
Step 17. Turn on the voltage sources.
a. Apply V
A
, V
B
, and V
C
at the magnitudes and angles
listed in Table 13.6.
b. Turn on the current test source.
c. Set the current angle to –82°. Slowly increase the
magnitude of current applied until the Z2G element
asserts, causing OUT106 to close. This occurs when
current applied is approximately 2.5 amps.
You might want to test the distance element
characteristic at impedance angles other than the line
positive-sequence impedance angle. To do this, you
must adjust the magnitude and angle of I
TEST
from the
values shown in Table 13.6.
d. As an example, calculate the current signal necessary to
test the distance element at an angle of 38.97°.
First, the new desired impedance angle (38.97°) is 45°
less than the original test impedance angle (83.97°).
Z2FT 1.25 Z2F 0.25 Z2m• –• =
2
1
3
---
40.4 0° 1 240° 67.0 120°–1120° 67.0 120°∠• ∠+∠• ∠+∠() volts• =
8.88 180° volts∠=
2
1
3
---
2.5 82.42°–∠() amps• =
0.83 82.42° amps–∠=
Z2c 10.66 ohms–=
Z2m 15.47ohms=
Z2FT 1.25 0.77()0.25 15.47()• –• =
Z2FT –2.91 ohms=
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