Schweitzer Engineering Laboratories SEL-351 - Monitoring Open Interval and Reset Timing; Reclosing Relay Shot Counter

Date Code 20001006 Close and Reclose Logic 6-19
SEL-351 Instruction Manual
Monitoring Open Interval and Reset Timing
Open interval and reset timing can be monitored with the following Relay Word bits:
Relay Word Bits Definition
OPTMN Indicates that the open interval
timer is actively timing
RSTMN Indicates that the reset timer is
actively timing
If the open interval timer is actively timing, OPTMN asserts to logical 1. When the relay is not
timing on an open interval (e.g., it is in the Reset State or in the Lockout State), OPTMN deasserts
to logical 0. The relay can only time on an open interval when it is in the Reclose Cycle State, but
just because the relay is in the Reclose Cycle State does not necessarily mean the relay is timing on
an open interval. The relay only times on an open interval after successful reclose initiation and
no stall conditions are present [see Skip Shot and Stall Open Interval Timing Settings (79SKP
and 79STL, respectively) later in this subsection].
If the reset timer is actively timing, RSTMN asserts to logical 1. If the reset timer is not timing,
RSTMN deasserts to logical 0. See Block Reset Timing Setting (79BRS) later in this subsection.
Reclosing Relay Shot Counter
Refer to Figure 6.6.
The shot counter increments for each reclose operation. For example, when the relay is timing on
open interval 1, 79OI1, it is at shot = 0. When the open interval times out, the shot counter
increments to shot = 1 and so forth for the set open intervals that follow. The shot counter cannot
increment beyond the last shot for automatic reclosing [see Determination of Number of
Reclosures (Last Shot) earlier in this subsection]. The shot counter resets back to shot = 0 when
the reclosing relay returns to the Reset State.
Table 6.3: Shot Counter Correspondence to Relay Word Bits and Open Interval Times
Shot
Corresponding
Relay Word Bit
Corresponding
Open Interval
0 SH0 79OI1
1 SH1 79OI2
2 SH2 79OI3
3 SH3 79OI4
4 SH4
When the shot counter is at a particular shot value (e.g., shot = 2), the corresponding Relay Word
bit asserts to logical 1 (e.g., SH2 = logical 1).
Courtesy of NationalSwitchgear.com