Schweitzer Engineering Laboratories SEL-311C, Instruction Manual

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13.26
SEL-311C Relay Instruction Manual
Date Code 20060320
Testing and Troubleshooting
Test Procedures
Step 9. Connect the current source to the A-phase relay current input.
Refer to the A-phase voltage and current connections shown in
Figure 13.5 as an example. The B-phase and C-phase voltage
connections are not required for this test.
As described above, the relay 32Q element operates based upon
the magnitude and angle of negative-sequence voltages and
currents.
Step 10. You can calculate the magnitude and angle of V
2
and I
2
, given
the magnitude and angle of each of the phase quantities,
through use of the following equations.
Equation 13.9
Using single-phase signals simplifies the V
2
and I
2
calculations.
V
B
= V
C
= 0 volts
I
B
= I
C
= 0 amps
Equation 13.10
Assume that you apply a test voltage V
A
= 18.0
∠
180° volts
secondary.
Equation 13.11
Determine the test angle of A-phase current from the Z1ANG
relay setting.
Equation 13.1 yields a positive result when I
2
lags
V
2
by the angle of Z1ANG°. Equation 13.1 yields a negative
result when I
2
leads V
2
by (180° –
∠
Z1ANG°).
We are testing for positive values of Z2c, so I
2
should lag V
2
by
Z1ANG.
Assuming that V
A
= 18.0
∠
180° volts, the angle of I
A
for this
test should be 96°.
Determine the magnitude of A-phase current where Z2 equals
Z2R or Z2F through use of
Equation 13.12 :
Equation 13.12
V
2
1
3
---
V
A
a
2
V
B
a V
C
• + • +
( )
• =
I
2
1
3
---
I
A
a
2
I
B
a I
C
• + • +
( )
• =
V
2
1
3
---
V
A
( )
• =
I
2
1
3
---
I
A
( )
• =
V
2
1
3
---
18.0 180
° ∠ ( )
volts • =
6.0 180
° ∠
volts =
I
A
3
V
2
Z
2
---------
⎝ ⎠
⎛ ⎞
• =