Schweitzer Engineering Laboratories SEL-311L, Instruction Manual, Page: 229 / 734

Date Code 20010625 Close and Reclose Logic 6-11
SEL-311L Instruction Manual
settings for the SEL-311L(2) Relay (see Figure 7.23 and Figure 7.24). Note the built-in
3-cycle qualification of the synchronism check voltages shown in Figure 3.53.
Additional Settings Example 2
Refer to subsection Synchronism Check Elements in Section 3: Line Current Differential,
Distance, Out-of-Step, Overcurrent, Voltage, Synchronism Check, and Frequency Elements .
Also refer to Figure 6.3 and Figure 6.4.
If the synchronizing voltages across open circuit breaker 52/2 are “slipping” with respect to one
another, the Reclose Supervision Limit Timer setting 79CLSD should be set greater than zero so
there is time for the slipping voltages to come into synchronism. For example:
79CLSD = 60.00 cycles
79CLS = 25A1
The status of synchronism check element 25A1 is checked continuously during the 60-cycle
window. If the slipping voltages come into synchronism while timer 79CLSD is timing,
synchronism check element 25A1 asserts to logical 1 and reclosing proceeds.
In the above referenced subsection Synchronism Check Elements , note item 3 under
Synchronism Check Element Outputs , Voltages V
P
and V
S
are “Slipping.” Item 3 describes a
last attempt for a synchronism check reclose before timer 79CLSD times out (or setting 79CLSD
= 0.00 and only one check is made).
R
ECLOSING
R
ELAY
Note that input:
Reclosing Relay Open Interval Time-Out
in Figure 6.2 is the logic input that is qualified by SEL
OGIC
control equation setting 79CLS, and
then propagated onto the close logic in Figure 6.1 to automatically reclose a circuit breaker. The
explanation that follows in this reclosing relay subsection describes all the reclosing relay
settings and logic that eventually result in this open interval time-out logic input into Figure 6.2.
Other aspects of the reclosing relay are also explained. Up to four (4) automatic reclosures
(shots) are available.
The reclose enable setting, E79, has setting choices N, 1, 2, 3, and 4. Setting E79 = N defeats the
reclosing relay. Setting choices 1 through 4 are the number of desired automatic reclosures (see
Open Interval Timers that follows in this subsection).