Schweitzer Engineering Laboratories SEL-311C - Page 509

13.55
Date Code 20060320 Instruction Manual SEL-311C Relay
Testing and Troubleshooting
Test Procedures
Equation 13.90
Equation 13.91
Equation 13.92
Taking the test signals from Table 13.8:
V
A
= 40.0 V ∠0°
V
B
= 67.0 V ∠–120°
V
C
= 67.0 V ∠120°
Equation 13.93
I
A
= 8.0 ∠0.0°
I
B
= 0.0 ∠0.0°
I
C
= 0.0 ∠0.0°
Equation 13.94
Through use of Equation 13.90 to calculate Z2c, we obtain the
following result:
Equation 13.95
The relay example Z2F setting is 0.77 Ω. The value of Z2c
applied (–3.37 Ω) is less than the Z2FT threshold (0.12 Ω), so
the 32QF element should assert 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 14. Turn on the voltage sources.
a. Apply V
A
, V
B
, and V
C
at the magnitudes and angles
listed in Table 13.8.
b. Turn on the current test source.
c. Set the current angle to 0.0°.
d. Slowly increase the magnitude of current applied until
the Z2G element asserts, causing OUT106 to close. This
occurs when current applied is approximately 8.0 amps.
Z2c
Re V
2
1 Z1ANG°∠ I
2
• ()*• []
I
2
2
----------------------------------------------------------------------------=
Z2m
V
2
I
2
---------=
Z2FT 1.25 Z2F 0.25 Z2m• –• =
V
2
1
3
---
40.0 0° 1240° 67.0 120°–1120° 67.0 120°∠• ∠+∠• ∠+∠()volts• =
9.0 180°volts∠=
I
2
1
3
---
8.0 0.0°∠()amps• =
2.67 0.0°amps∠=
Z2c 3.37 ohms–=
Z2m 3.37ohms=
Z2FT 1.25 0.77()0.25 3.37()• –• =
Z2FT 0.12 ohms=
NOTE: As you perform this test,
other protection elements can assert,
causing the relay to close other
output contacts and assert relay
targets. This is normal and is not a
cause for concern.