7 Acceptance/Protection Function Test Guide
7-18
L-PRO 4000 User Manual
D02706R02.30
3. Now determine the 3-phase voltage phasors.
Only B-C fault is shown here, but the same principle applies for A-B or C-
A faults.
Since neutral is not involved in this type of fault, the faulted voltage phasors
collapse toward each other along the phase-to-phase line.
Figure 7.12: Phasor Representation of an Ideal Phase-to-Phase Fault
The following tables show the voltages to inject for a variety of fault voltage
levels using 115 V secondary phase-to-phase nominal (66.4 V phase-to-neutral
nominal).
0 deg
FAULT
VOLTS
HEALTHY
VOLTS
-120 deg
120 deg
A
B
C
N
Table 7.14: A-B Fault Voltage Injections
A-B Fault
(C-phase voltage = 66.4 V
+120
) The resultant angle of A-B voltage always = +30
% Reduction
10%
20%
30%
40%
50%
60%
70%
80%
90%
Fault V
103.5 V
92.0 V
80.5 V
69.0 V
57.5 V
46.0 V
34.5 V
23.0 V
11.5 V
Fault Volt Angle
30
30
30
30
30
30
30
30
30
Voltage A=B
61.5 V
56.7 V
52.2 V
47.9 V
43.9 V
40.4 V
37.4 V
35.1 V
33.7 V
A Angle
-2.7
-5.8
-9.5
-13.9
-19.1
-25.3
-32.5
-40.9
-50.2
B Angle
-117.3
-114.2v
-110.5
-106.1
-100.9
-94.7
-87.5
-79.1
-69.8
Summary of Contents for L-PRO 4000
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Page 252: ...Appendix B IED Settings and Ranges Appendix B 34 L PRO 4000 User Manual D02706R02 30...
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