Schweitzer Engineering Laboratories SEL-351-5, Instruction Manual

Page: 263 / 706

6.25
Date Code 20070117
Instruction Manual SEL-351-5, -6, -7 Relay
Close and Reclose Logic
Reclosing Relay
If line voltage is present, Relay Word bit 59S1 asserts, stalling open interval
timing (reclose block). If line voltage is not present, Relay Word bit 59S1
deasserts, allowing open interval timing to proceed (unless some other set
condition stalls open interval timing).
Additional Settings Example 3
Refer to Figure 6.4 and accompanying setting example, showing an
application for setting 79STL.
Other Settings Considerations
If no special skip shot or stall open interval timing conditions are desired,
make the following settings:
79SKP = 0 (numeral 0)
79STL =
0
(numeral 0)
Block Reset Timing
Setting (79BRS)
The block reset timing setting 79BRS keeps the reset timer from timing.
Depending on the reclosing relay state, the reset timer can be loaded with
either reset time:
79RSD (Reset Time from Reclose Cycle)
or
79RSLD (Reset Time from Lockout)
Depending on how setting 79BRS is set, none, one, or both of these reset
times can be controlled. If the reset timer is timing and then 79BRS asserts to:
79BRS = logical 1
reset timing is stopped and does not begin timing again until 79BRS deasserts
to:
79BRS = logical 0
When reset timing starts again, the reset timer is fully loaded. Thus, successful
reset timing has to be continuous. Use the RSTMN Relay Word bit to monitor
reset timing (see
Monitoring Open Interval and Reset Timing on page 6.18 ).
Factory Settings Example
The block reset function is not enabled in the factory settings:
79BRS =
0
(numeral 0)
Additional Settings Example 1
The block reset timing setting is:
79BRS = (51P + 51G) * 79CY
Relay Word bit 79CY corresponds to the Reclose Cycle State. The reclosing
relay is in one of the three reclosing relay states at any one time (see
Figure 6.5 and Table 6.1 ).
When the relay is in the Reset or Lockout States, Relay Word bit 79CY is
deasserted to logical 0. Thus, the 79BRS setting has no effect when the relay
is in the Reset or Lockout States. When a circuit breaker is closed from
lockout, there could be cold load inrush current that momentarily picks up a