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5 SETPOINTS
If the fault is permanent, subsequent overcurrent element(s) will trip and initiate reclosure. The scheme will eventually go to
lockout when the
MAX NUMBER OF RECLOSURE SHOTS
detected at any time during operation, the scheme will again go straight to lockout. When in lockout, the 760 disables the
reclose scheme and returns all protection setpoints to their initial values. To re-enable the autoreclose scheme the relay
must be reset via the front panel reset key, the Reset logic input function, communications, or by a manual close operation.
The latter resets the scheme only after the
are active.
If the fault is transient in nature then no overcurrent element(s) will trip after the breaker has closed. The scheme will auto-
matically reset when the reset timer, started upon the first reclosure initiation, exceeds the
This autoreclosure reset returns the shot counter to zero and all protection setpoints to their initial values.
An anti-pumping feature is built into the reset mechanism. Otherwise, breaker pumping could occur when the fault level is
between the initial overcurrent pickup level and the adjusted overcurrent pickup level for a reclosure shot. It prevents a per-
manent fault from continuously repeating the trip breaker, initiate reclose, close breaker, automatic reset of autoreclose
scheme, trip breaker sequence. If this condition is detected the anti-pumping feature returns protection setpoints to their ini-
tial values without resetting the shot counter. The relay will then continue to trip and reclose until lockout is reached.
b) SCHEME SETUP
PATH: SETPOINTS
S7 CONTROL
SCHEME SETUP
[ENTER] for more
The setpoints shown above setup the general characteristics of the scheme. The
setpoints are critical and must be set appropriately.
SURE SHOTS
For an overcurrent element to initiate a reclosure it must be set to the "Trip & AR" function.
NOTE
•
MAX NUMBER OF RECLOSURE SHOTS: This setpoint specifies the number of reclosures that should be attempted
before reclosure lockout occurs. The dead time and overcurrent characteristics for each reclosure shot are entered in
the subsequent message groups
•
AR RESET TIME: The reset timer is used to set the total time interval for a single fault event, from the first trip until
either lockout or successful reclosure. Generally, this setpoint is set to the same delay that would be used for the
'reclaim time' in a traditional scheme with fixed protection settings. This time must be set to a value greater than the
sum of all programmed dead times plus the maximum time to trip on each reclose shot.
GE Multilin
Courtesy of NationalSwitchgear.com
has been met and another trip occurs. If a breaker failure condition is
AR BLOCK TIME UPON MANUAL CLOSE
AR
SCHEME SETUP
ð
AR
ENTER
ESCAPE
FUNCTION: Disabled
MAX NUMBER OF
ESCAPE
MESSAGE
RECLOSURE SHOTS: 1
AR RESET
ESCAPE
MESSAGE
TIME: 60 s
AR BLOCK TIME UPON
ESCAPE
MESSAGE
MANUAL CLOSE: 10 s
AR EXTERNAL CLOSE
ESCAPE
MESSAGE
LOGIC: Disabled
INCOMPLETE SEQUENCE
ESCAPE
MESSAGE
TIME: 30 s
RECLOSURE ENABLED
ESCAPE
MESSAGE
RELAYS (3-7): -----
RECLOSURE IN PROGRESS
ESCAPE
MESSAGE
RELAYS (3-7): -----
RECLOSURE LOCKOUT
ESCAPE
MESSAGE
RELAYS (3-7): -----
to
RECLOSURE 1
RECLOSURE 4
750/760 Feeder Management Relay
timer expires, and no overcurrent elements
AR RESET TIME
Range: Enabled, Disabled
Range: 1 to 4 in steps of 1
Range: 1 to 1000 s in steps of 1
Range: 0 to 200 s in steps of 1
Range: Enabled, Disabled
Range: 1 to 1000 s in steps of 1
Range: Any combination of the 3 to 7 Auxiliary relays
Range: Any combination of the 3 to 7 Auxiliary relays
Range: Any combination of the 3 to 7 Auxiliary relays
and
AR FUNCTION
.
5.8 S7 CONTROL
setpoint value.
5
MAX NUMBER OF RECLO-
5-119
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