Date Code 20151029 Protection Manual SEL-411L Relay
Section 4
P.Protection Manual
Autoreclosing and Synchronism-Check
This section describes the operation of autoreclose logic in the relay. Also
included in this section is a discussion of Voltage Check logic and
Synchronism-Check logic that can be used with autoreclosing or applied
independently. This section covers the following topics:
➤ Autoreclosing on page P.4.2
➤ One-Circuit-Breaker Autoreclosing on page P.4.4
➤ Two-Circuit-Breaker Autoreclosing on page P.4.10
➤ Autoreclose Logic Diagrams on page P.4.27
➤ Manual Closing on page P.4.40
➤ Voltage Checks for Autoreclosing and Manual Closing on
page P.4.43
➤ Settings and Relay Word Bits for Autoreclosing and Manual
Closing on page P.4.45
➤ Synchronism Check on page P.4.49
The relay autoreclose and synchronism-check functions provide complete
control for single-circuit breaker and two-circuit breaker reclosing schemes.
The autoreclose function accommodates both single-pole and three-pole
reclosing. You can set the autoreclose function for a total of two single-pole
and four three-pole reclose shots. The single-pole shots have a common dead
time, while the three-pole shots have individual dead times. You can designate
the leader and follower circuit breakers in a two-circuit breaker configuration;
the recloser can dynamically change leader and follower designations based
on settings and operating conditions.
You can program the autoreclose logic to perform one shot of high-speed
three-pole reclose. This high-speed three-pole shot replaces one of the four
delayed time three-pole shots. There is no difference between a shot of high-
speed three-pole reclose and a shot of delayed three-pole autoreclose; simply
select the open interval time accordingly.
Two autoreclose modes are available when using the relay to control two
circuit breakers:
➤ Combined two-breaker mode (setting E79 := Y)—both circuit
breakers must trip before any reclosing can occur.
➤ Independent two-breaker mode (setting E79 := Y1)—the
follower circuit breaker can trip and reclose even when the lead
breaker has not operated. This is useful on both ring bus and
breaker-and-a-half schemes, where the follower breaker is a tie
breaker that can be tripped by protection on either side.
For single circuit breaker applications, use setting E79 := Y.
NOTE: The relay voltage check
elements (for bus and line voltages)
may be used without the
synchronism-check feature, however,
for certain voltage connections, some
of the synchronism-check settings
need to be entered to ensure that the
correct voltages are used.
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