E. Phase-Phase Mho Element Tests
Purpose:
Use the LOGIC command to program a single output relay (A1-A4) to follow
the appropriate instantaneous phase-phase distance element. Select a phase-
phase element from the Relay Word as indicated below:
Determine the pickup of the phase-phase distance element at three points on the
mho characteristic: MTA, MTA +45° and MTA -45°.
Method: 1.
Z1P
= Zone 1 Instantaneous Phase-Phase Distance Element
Z2PT
= Zone 2 Time Delayed Phase-Phase Distance Element
Z3
= Zone 3 Instantaneous Phase and Ground Distance Element
Please note the Z2PT element includes any delay set by the Z2DP timer.
The following example outlines the test procedure for the Zone 1 phase distance
element.
2.
Connect the sources of voltage and current to the relay rear panel terminals (see
Figure 7.9a or b). Note that two current sources are employed in Figure 7.9a,
while only one current source is used in Figure 7.9b.
The single current source method yields the same results as the two current
source method. Single current source method also assures that the phase angle
of the two involved currents is always 180° apart.
These steps connect a single current source to the relay for a BC phase-phase
fault test.
a.
Connect B current source dotted output to dotted relay IB input
(Terminal 31).
b.
Jumper undotted relay IB and IC current inputs together (Terminals 32 and
34 respectively).
c.
Connect dotted relay IC current input to common current source return of
current Source B (Terminal 33 to source common current return).
7-22
Maintenance & Testing
SEL-221F, -1 Instruction Manual
Date Code 920508
Summary of Contents for SEL-221F
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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 ...