5.5 GROUPED ELEMENTS
BF1 USE SEAL-IN:
If set to Yes, the element will only be sealed-in if current flowing through the breaker is above the supervision pickup level.
BF1 3-POLE INITIATE:
This setting is used to select the FlexLogic™ operand that will initiate 3-pole tripping of the breaker.
BF1 PH AMP SUPV PICKUP:
This setting is used to set the phase current initiation and seal-in supervision level. Generally this setting should detect the
lowest expected fault current on the protected breaker. It can be set as low as necessary (lower than breaker resistor cur-
rent or lower than load current) - Hiset and Loset current supervision will guarantee correct operation.
BF1 N AMP SUPV PICKUP (valid only for 3-pole breaker failure schemes):
This setting is used to set the neutral current initiate and seal-in supervision level. Generally this setting should detect the
lowest expected fault current on the protected breaker. Neutral current supervision is used only in the three phase scheme
to provide increased sensitivity.
BF1 USE TIMER 1:
If set to Yes, the Early Path is operational.
BF1 TIMER 1 PICKUP DELAY:
Timer 1 is set to the shortest time required for breaker auxiliary contact Status-1 to open, from the time the initial trip signal
is applied to the breaker trip circuit, plus a safety margin.
BF1 USE TIMER 2:
If set to Yes, the Main Path is operational.
BF1 TIMER 2 PICKUP DELAY:
Timer 2 is set to the expected opening time of the breaker, plus a safety margin. This safety margin was historically
intended to allow for measuring and timing errors in the breaker failure scheme equipment. In microprocessor relays this
time is not significant. In UR relays, which use a Fourier transform, the calculated current magnitude will ramp-down to zero
one power frequency cycle after the current is interrupted, and this lag should be included in the overall margin duration, as
it occurs after current interruption. The BREAKER FAILURE MAIN PATH SEQUENCE diagram shows a margin of two
cycles; this interval is considered the minimum appropriate for most applications.
Note that in bulk oil circuit breakers, the interrupting time for currents less than 25% of the interrupting rating can be signifi-
cantly longer than the normal interrupting time.
BF1 USE TIMER 3:
If set to Yes, the Slow Path is operational.
BF1 TIMER 3 PICKUP DELAY:
Timer 3 is set to the same interval as Timer 2, plus an increased safety margin. Because this path is intended to operate
only for low level faults, the delay can be in the order of 300 to 500 ms.
BF1 BKR POS1
This setting selects the FlexLogic™ operand that represents the protected breaker early-type auxiliary switch contact (52/
a). When using 1-Pole breaker failure scheme, this operand represents the protected breaker early-type auxiliary switch
contact on pole A. This is normally a non-multiplied Form-A contact. The contact may even be adjusted to have the shortest
possible operating time.
BF1 BKR POS2
This setting selects the FlexLogic™ operand that represents the breaker normal-type auxiliary switch contact (52/a). When
using 1-Pole breaker failure scheme, this operand represents the protected breaker auxiliary switch contact on pole A. This
may be a multiplied contact.
BF1 BREAKER TEST ON:
This setting is used to select the FlexLogic™ operand that represents the breaker In-Service/Out-of-Service switch set to
the Out-of-Service position.
L90 Line Differential Relay
GE Power Management