6-26
Close and Reclose Logic
Date Code 20001006
SEL-351 Instruction Manual
Table 6.5: Open Interval Time Factory Settings
Shot
Corresponding
Relay Word Bit
Corresponding
Open Interval
Open Interval Time
Factory Setting
0
SH0
79OI1
30 cycles
1
SH1
79OI2
600 cycles
In Table 6.5, note that the open interval 1 time (setting 79OI1) is a short time, while the following
open interval 2 time (setting 79OI2) is significantly longer. For a high magnitude fault (greater
than the phase instantaneous overcurrent element 50P2 threshold), open interval 1 time is skipped,
and open interval timing proceeds on the following open interval 2 time.
Once the shot is incremented to shot = 1, Relay Word bit SH0 = logical 0 and then setting 79SKP
= logical 0, regardless of Relay Word bit 50P2.
Additional Settings Example 2
If the SEL-351 Relay is used on a feeder with a line-side independent power producer
(cogenerator), the utility should not reclose into a line still energized by an islanded generator. To
monitor line voltage and block reclosing, connect a line-side single-phase potential transformer to
channel VS on the SEL-351 Relay as shown in Figure 6.7.
Figure 6.7: Reclose Blocking for Islanded Generator
If the line is energized, channel VS overvoltage element 59S1 can be set to assert. Make the
following setting:
79STL
= 59S1 + ...
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).
Содержание SEL-351
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