Referring to Figure 5.7 at t = 0, a permanent phase-phase fault occurs within the relay
Zone 1 reach. The relay detects the fault and asserts the TRIP outputs, fulfilling the first
requirement to initiate the reclosing sequence. Because the Z1P Zone 1 phase distance
element is set in the Mask for Reclose Initiate, reclosure is initiated.
In response to the relay TRIP signal, the line breaker opens. This causes the RI bit to
deassert because the Z1P element drops out. When the breaker opens, the breaker auxiliary
contact also opens, deasserting the relay 52A input.
The relay TDUR setting of nine cycles causes the TRIP to remain asserted until cycle 11. No
reclose cancel condition occurred, and the other three initiating conditions were fulfilled, so
the 79OI timer starts when TRIP drops out.
Forty cycles later, the 79OI timer expires. The relay issues the CLOSE signal, the breaker
recloses, and the 52A input is asserted by closure of the breaker auxiliary contact.
When the breaker closes, the phase-phase fault is reenergized. The relay Z1P element picks
up causing the relay to TRIP and the RI bit to assert. Again, the breaker opens and the 52A
input deasserts. Because the available reclosing shot has operated, when the relay trips a
second time, the recloser is locked out and the breaker remains open.
Example 2: Reclosing Cancelled Due to RC Assertion
In this example, the fault is a Zone 3 phase-ground fault. The fault was not cleared by the
primary protection, so this relay tripped due to assertion of the time delayed Zone 3 distance
element, Z3T. Because the Z3T bit is set in the Mask for Reclose Cancel, the reclose cancel
condition is fulfilled, cancelling the reclosing shot. Figure 5.8 illustrates the timing of the
example.
Because Reclose Cancel has precedence over Reclose Initiate, the reclosing sequence is
cancelled any time RC asserts while the TRIP is asserted, regardless of the presence of
Reclose Initiating conditions.
Figure 5.8: Reclosing Cancelled Due to RC Assertion
5-38
Applications
SEL-221F, -1 Instruction Manual
Date Code 920508
Содержание SEL-221F
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Страница 158: ...SETTINGS SHEET FOR SEL 221F RELAY PAGE 2 OF 6 DATE Date Code 921110 ...
Страница 160: ...SETTINGS SHEET PAGE 4 OF 6 FOR SEL 221F RELAY DATE Date Code 930601 ...
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Страница 170: ...Figure 6 2 Horizontal Front and Rear Panel Drawings Date Code 920508 Installation 6 7 SEL 221F 1 Instruction Manual ...
Страница 174: ...Figure 6 8 Dc External Connection Diagram Typical Date Code 920508 Installation SEL 221F 1 Instruction Manual 6 11 ...
Страница 228: ...APPENDICES TABLE OF CONTENTS Parts Placement Diagram Date Code 920508 Table of Contents SEL 221F 1 Instruction Manual i ...
Страница 229: ...SEL 200 Series Relay Main Board Troubleshooting Test Points and Jumper Locations ...