Date Code 20001006
Inputs, Outputs, Timers, and Other Control Logic
7-33
SEL-351 Instruction Manual
Optoisolated input IN1 functions as a breaker failure initiate input. Phase instantaneous overcur-
rent element 50P1 and neutral ground instantaneous overcurrent element 50N1 function as fault
detectors.
Timer pickup setting SV6PU provides retrip delay, if desired (can be set to zero). Timer dropout
setting SV6DO holds the retrip output (output contact OUT1) closed for extra time if needed after
the breaker failure initiate signal (IN1) goes away.
Timer pickup setting SV7PU provides breaker failure timing. Timer dropout setting SV7DO holds
the breaker failure trip output (output contact OUT2) closed for extra time if needed after the
breaker failure logic unlatches (fault detectors 50P1 and 50N1 dropout).
Note that Figure 7.27 suggests the option of having output contacts OUT3 and OUT4 operate as
additional breaker failure trip outputs. This is done by making the following SEL
OGIC
Control
Equation settings:
OUT3 = SV7T
(breaker failure trip)
OUT4 = SV7T
(breaker failure trip)
Additional Settings Example 2
The seal-in logic circuit in the dedicated breaker failure scheme in Figure 7.27 can be removed by
changing the SEL
OGIC
Control Equation setting SV7 to:
SV7 = IN1*(50P1 + 50N1)
If the seal-in logic circuit is removed, optoisolated input IN1 (breaker failure initiate) has to be
continually asserted for a breaker failure time-out.
Timers Reset When Power is Lost, Settings are Changed, or Active Setting Group is
Changed
If power is lost to the relay, settings are changed (for the active setting group), or the active setting
group is changed, the SEL
OGIC
Control Equation variables/timers are reset. Relay Word bits SVn
and SVnT (n = 1 through 16) are reset to logical 0 and corresponding timer settings SVnPU and
SVnDO load up again after power restoration, settings change, or active setting group switch.
Preceding Figure 7.27 shows an effective seal-in logic circuit, created by use of Relay Word bit
SV7 (SEL
OGIC
Control Equation variable SV7) in SEL
OGIC
Control Equation SV7:
SV7 = (SV7 + IN1)*(50P1 + 50N1)
If power is lost to the relay, settings are changed (for the active setting group), or the active setting
group is changed, the seal-in logic circuit is “broken” by virtue of Relay Word bit SV7 being reset
to logical 0 (assuming input IN1 is not asserted). Relay Word bit SV7T is also reset to logical 0,
and timer settings SV7PU and SV7DO load up again.
Summary of Contents for SEL-351
Page 14: ...Courtesy of NationalSwitchgear com ...
Page 16: ...Courtesy of NationalSwitchgear com ...
Page 40: ...Courtesy of NationalSwitchgear com ...
Page 74: ...Courtesy of NationalSwitchgear com ...
Page 146: ...Courtesy of NationalSwitchgear com ...
Page 186: ...Courtesy of NationalSwitchgear com ...
Page 220: ...Courtesy of NationalSwitchgear com ...
Page 304: ...Courtesy of NationalSwitchgear com ...
Page 340: ...Courtesy of NationalSwitchgear com ...
Page 380: ...Courtesy of NationalSwitchgear com ...
Page 450: ...Courtesy of NationalSwitchgear com ...
Page 506: ...Courtesy of NationalSwitchgear com ...
Page 528: ...Courtesy of NationalSwitchgear com ...
Page 534: ...Courtesy of NationalSwitchgear com ...
Page 536: ...Courtesy of NationalSwitchgear com ...
Page 550: ...Courtesy of NationalSwitchgear com ...
Page 562: ...Courtesy of NationalSwitchgear com ...
Page 570: ...Courtesy of NationalSwitchgear com ...
Page 584: ...Courtesy of NationalSwitchgear com ...
Page 602: ...Courtesy of NationalSwitchgear com ...