To calculate I2, substitute currents for voltages in the equations above.
Please note that the angular relationship of V2 and I2 using a single voltage and
current differs by 180° from using three voltages and a single current. Figure
7.11 illustrates the difference between using a single voltage and current and
using three voltages and a single current. For the sake of simplicity, this test
uses the single voltage and current method. The relay declares ground faults in
the forward direction when I2 leads V2 ± 90° from the MTA.
I2 LEADS V2
I2 LAGS V2
(I0 LEADS V0)
(I0 LAGS V0)
Figure 7.11: Three Voltage vs. One Voltage for Directional Tests
2 . Apply IA = 3 amperes, corresponding to negative-sequence currents of one
ampere. IB and IC are zero for this test.
3.
Move the phase angle of the current with respect to the voltage and observe the
boundary of the directional element at MTA ±90°.
Date Code 920508
Maintenance & Testing
SEL-221F, -1 Instruction Manual
7-29
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 ...