GE 750, Instruction Manual

Page: 276 / 504

14-
20
750/760 Feeder Management Relay GE Power Management
14.7 TRANSFER 14 S7 CONTROL
14
14.7.2 SETPOINTS
14.7.3 SETTINGS/FUNCTIONS OF ASSOCIATED ELEMENTS
Output Relays 4-7 Auxiliary (All breakers)
These output relays are used to implement the transfer scheme, and must therefore not be operated by any
other feature of the relay. These relays must be programmed to have a non-operated state of ‘De-energized’
with the output type as ‘Self-reset’. These are the default settings.
Instantaneous Phase-1 or 2 (50P1 or 2) and Instantaneous Neutral-1 or 2 (50N-1 or 2)
(Incomers 1 and 2 only)
These fault detectors can be used as an input to transfer scheme logic in this application, and therefore the
function setpoint of elements that are used must be set to
Control . These elements block a transfer while a
fault, which can cause a severe voltage dip, is present on the load side of the breaker. This fault should be
cleared by time overcurrent protection on the incomer or an upstream breaker. If 50P is set properly, during this
event it will allow the 27-4 element to time out before the inverse time phase overcurrent operates, but still pre-
vent transfer initiation. The 50P element should be set above the maximum current caused by either the bus
motor contribution to an upstream fault, or the maximum current during low voltage conditions. The 50N ele-
ment should be set to detect arcing ground faults, but allow permitted unbalances.
■
TRANSFER
■
[ENTER] for more
The Transfer setpoints path is:
\ SETPOINTS \ S7 CONTROL \ TRANSFER
TRANSFER FUNCTION:
Disabled
Range: Disabled, Incomer 1, Incomer 2, Bus Tie
If the transfer scheme is not required select
Disabled
for this setpoint. If not
disabled, this setpoint is used to assign to the relay the function of the associ-
ated circuit breaker. This selection programs the relay to use the logic required
by each of the three breakers. Select
Incomer 1
or
Incomer 2
for this setpoint if
the relay is associated with the breaker to be used as Incomer 1 or 2 respec-
tively. Select
Bus Tie
if the relay is associated with the bus tie breaker.
TRANSFER DELAY THIS
SOURCE: 1.0 s
Range: 0.0 to 10.0 in steps of 0.1 s
This delay time establishes an interval from the reset of an operated instanta-
neous overcurrent element on this source, during which the line instantaneous
undervoltage element (27-3) is allowed to block a transfer. Select the desired
delay.
TRANSFER DELAY
OTHER SOURCE: 3.0 s
Range: 0.0 to 10.0 in steps of 0.1 s
This delay time prevents transfers that could otherwise be caused by a non-
simultaneous return of source voltages after a loss of both sources. It estab-
lishes an interval from the return of the first source to the return of the second
source during which a transfer cannot be initiated. Select the desired delay.
BLOCK TRIP ON DOUBLE
LOSS: Disabled
Range: Disabled, Enabled
This setpoint selects the required scheme operation in the event of a simulta-
neous loss of both source 1 and source 2. If it is desired to have both of the
Incomers trip on timed undervoltage when this occurs, select
Disabled . If it is
desired to prevent the Incomers from tripping on timed undervoltage when this
occurs, select
Enabled . With either selection a transfer-initiated close of the
bus tie breaker is not allowed.