Breaker Failure / Welded Contactor (50Bf) - GE 339 Instruction Manual

S4 CONTROLS

Breaker failure / Welded contactor (50BF)

NOTE:
NOTE
6–130
The Breaker Failure or Welded Contactor function monitors the phase currents, after a trip
command from the protection elements is initiated, or a logic operand programmed as BF
EXT INITIATE / WELDED EXT INI is asserted. The external initiating logic operand can be a
Contact Input, a Virtual Input, a Remote Input, or an output from a Logic Element. If any
phase current is above the set current level after the programmed time delay, a BREAKER
FAILURE will be declared when BREAKER was chosen for SWITCHING DEVICE, or a WELDED
CONTACTOR will be declared when CONTACTOR was chosen for SWITCHING DEVICE, and
the selected output relays will be activated. The time delay should be set slightly longer
than the breaker or contactor operating time.
To provide user flexibility, the 339 has included two programmable timers for the Breaker
Failure / Welded Contactor function. The timers can be used singularly or in combination
with each other. BF/Welded Time Delay 1 starts counting down once a trip condition is
recognized or the programmed logic operand is asserted. BF/Welded Time Delay 2 does
not begin counting down until BF/Welded Time Delay 1 has expired and one of the phase
currents is above the setting BF/Welded Current. If one of the delays is not required, simply
program the unwanted timer to its minimum value.
When the switching device is selected as CONTACTOR, this feature is displayed as WELDED
CONTACTOR.
The following path is available using the keypad. For instructions on how to use the
keypad, please refer to Chapter 3 - Working with the Keypad.
PATH:
SETPOINTS > S4 CONTROLS > BREAKER FAIL (WELDED CONTACTOR)
BF FUNCTION / WELDED CONT FUNC
Range: Disabled, Alarm, Latched Alarm
Default: Disabled
For details see Common
BF CURRENT / WELDED CURRENT
Range: 0.05 to 20.00 x CT in steps of 0.01
Default: 1.00 x CT
This setting specifies the current level monitored by the Breaker Failure / Welded
Contactor logic. Program this setting to a current level that can detect the lowest
expected fault current on the protected breaker/contactor.
BF EXT INITIATE / WELDED EXT INI
Range: Off, Contact Input 1 to 10, Virtual Input 1 to 32, Remote Input 1 to 32, Logic
Element 1 to 16, CT Fail Alarm PKP, CT Fail Alarm OP
Default: Off
This setting allows the user to select a logic operand to externally initiate the Breaker
Failure / Welded Contactor logic.
BF TIME DELAY 1 / WELDED TIME DELAY 1
Range: 0.03 to 1.00 s in steps of 0.01 s
Default: 0.10 s
This timer starts when breaker trip command is issued from any of the protection
elements, or a programmed external initiating logic operand is asserted.
BF TIME DELAY 2 / WELDED TIME DELAY 2
Range: 0.00 to 1.00 s in steps of 0.01 s
Default: 0.00 s
This timer does not start until a trip command is recognized, timer BF / WELDED TIME
DELAY1 has expired, and at least one of the phase currents is above the setting BF /
WELDED CURRENT.
setpoints.
339 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 6: SETPOINTS