GE T60, Instruction Manual

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GE Multilin T60 Transformer Protection System 5-253
5 SETTINGS 5.6 GROUPED ELEMENTS
5
• 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 equip-
ment. In microprocessor relays this time is not significant. In T60 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 below 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
significantly 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
φ
A /3P: This setting selects the FlexLogic operand that represents the protected breaker early-type
auxiliary switch contact (52/a). When using the single-pole breaker failure scheme, this operand represents the pro-
tected breaker early-type auxiliary switch contact on pole A. This is normally a non-multiplied form-A contact. The con-
tact may even be adjusted to have the shortest possible operating time.
• BF1 BKR POS2
φ
A /3P: This setting selects the FlexLogic operand that represents the breaker normal-type auxiliary
switch contact (52/a). When using the single-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.
• BF1 PH AMP HISET PICKUP: This setting sets the phase current output supervision level. Generally this setting
should detect the lowest expected fault current on the protected breaker, before a breaker opening resistor is inserted.
• BF1 N AMP HISET PICKUP: This setting sets the neutral current output supervision level. Generally this setting
should detect the lowest expected fault current on the protected breaker, before a breaker opening resistor is inserted.
Neutral current supervision is used only in the three pole scheme to provide increased sensitivity.
This setting is valid
only for three-pole breaker failure schemes .
• BF1 PH AMP LOSET PICKUP: This setting sets the phase current output supervision level. Generally this setting
should detect the lowest expected fault current on the protected breaker, after a breaker opening resistor is inserted
(approximately 90% of the resistor current).
• BF1 N AMP LOSET PICKUP: This setting sets the neutral current output supervision level. Generally this setting
should detect the lowest expected fault current on the protected breaker, after a breaker opening resistor is inserted
(approximately 90% of the resistor current).
This setting is valid only for three-pole breaker failure schemes .
• BF1 LOSET TIME DELAY: Sets the pickup delay for current detection after opening resistor insertion.
• BF1 TRIP DROPOUT DELAY: This setting is used to set the period of time for which the trip output is sealed-in. This
timer must be coordinated with the automatic reclosing scheme of the failed breaker, to which the breaker failure ele-
ment sends a cancel reclosure signal. Reclosure of a remote breaker can also be prevented by holding a transfer trip
signal on longer than the reclaim time.
• BF1 PH A INITIATE / BF1 PH B INITIATE / BF 1 PH C INITIATE: These settings select the FlexLogic operand to initi-
ate phase A, B, or C single-pole tripping of the breaker and the phase A, B, or C portion of the scheme, accordingly.
This setting is only valid for single-pole breaker failure schemes .
• BF1 BKR POS1
φ
B / BF1 BKR POS 1
φ
C: These settings select the FlexLogic operand to represents the protected
breaker early-type auxiliary switch contact on poles B or C, accordingly. This contact is normally a non-multiplied Form-
A contact. The contact may even be adjusted to have the shortest possible operating time.
This setting is valid only for
single-pole breaker failure schemes .
• BF1 BKR POS2
φ
B: Selects the FlexLogic operand that represents the protected breaker normal-type auxiliary switch
contact on pole B (52/a). This may be a multiplied contact. This setting is valid only for single-pole breaker failure
schemes .
• BF1 BKR POS2
φ
C: This setting selects the FlexLogic operand that represents the protected breaker normal-type
auxiliary switch contact on pole C (52/a). This may be a multiplied contact. For single-pole operation, the scheme has