RELAY REAR
PANEL VOLTAGE
AND CURRENT
INPUTS
THREE-PHASE
TEST SOURCE
Figure 7.8a: Three-Phase Voltage and Current Source Test Connections
for Three-Phase Fault Test
The two current source method yields the same results as does the three current
source method. For balanced three-phase faults, the residual or 310 is zero.
From this you can see why two current sources are adequate for three-phase
element testing:
3I0 = IA + IB + IC = 0
Therefore,
-IC = (IA + IB)
This has the same effect as performing the following steps:
a.
Connect the dotted output of A and B current sources to the dotted IA and
IB inputs of the relay (Terminals 29 and 31 respectively).
b.
Jumper together the undotted IA and IB current inputs of the relay
(Terminals 30 and 32 respectively). This forms the (IA + IB) quantity.
Date Code 940412
Maintenance & Testing
SEL-221F, -1 Instruction Manual
7-19
Summary of Contents for SEL-221F
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Page 110: ...Example Event Report 2 4 12 Event Reporting SEL 221F 1 Instruction Manual Date Code 930830 ...
Page 158: ...SETTINGS SHEET FOR SEL 221F RELAY PAGE 2 OF 6 DATE Date Code 921110 ...
Page 160: ...SETTINGS SHEET PAGE 4 OF 6 FOR SEL 221F RELAY DATE Date Code 930601 ...
Page 161: ...SETTINGS SHEET PAGE 5 OF 6 FOR SEL 221F RELAY DATE Date Code 961208 ...
Page 229: ...SEL 200 Series Relay Main Board Troubleshooting Test Points and Jumper Locations ...