GE L60 Instruction Manual page 176

5.5 GROUPED ELEMENTS
As operation of the permissive tripping mode of phase comparison protection and tripping of the line is fundamentally
dependent on transmitting the signal to the remote end of the line, some cases of system operating conditions require
attention:
1. If a line is open at one end, the phase comparison element is unable to detect an internal fault and give trip permission
to the remote terminal relay.
2. A weak-infeed or no fault infeed at one end of the faulted line may prevent phase comparison element trip. Conse-
quently, instant conversion from weak-infeed logic with sending permissive continuous signal to fault logic with sending
square waves is required in case of the external fault at the adjacent or internal fault for proper operation of phase
comparison relay at the remote line's terminal.
The Open Breaker Echo element should be applied to any particular application according to local system conditions. The
element settings are described below:
• OPEN BREAKER KEYING: Disables/enables the open breaker keying feature.
• BRK 1 AUX CONTACT: Assigns a FlexLogic™ operand to control open/close state of Breaker #1 with either 52a or
52b type contact to create logic "1" when the breaker is open.
• BRK 1 CONT SUPV: Selects a supervising element such as a test/normal switch usually used in Breaker #1 control
schemes or any other elements. If no element is required, the default value "Off" should be used.
• BRK 2 AUX CONTACT: If supervision of two breakers is required, this setting is used to assign a FlexLogic™ operand
to control open/close state of the Breaker #2 with either 52a or 52b type contact to create logic "1" when the breaker is
open.
• BRK 2 CONT SUPV: Selects a supervising element such as a test/normal switch usually used in Breaker #2 control
schemes or any other elements. If no element is required, the default value "Off" should be used.
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• OPEN BREAKER KEYING PKP DELAY: Delays the operation of open breaker keying to override disagreement
between main and auxiliary contacts of the breaker or any other operating conditions.
• OPEN BREAKER KEYING RST DELAY: Delays the reset of open breaker keying to override disagreement between
main and auxiliary contacts of the breaker or any other operating conditions.
• WEAK-INFEED KEYING: This setting assigns a sensitive phase-current element for weak-infeed keying control. It
should be normally picked up with a minimum line load current. An instantaneous overcurrent element or a group of
overcurrent elements are suitable for this purpose.
• WEAK-INFEED SUPV: This setting selects a weak-infeed supervising element from FlexLogic™ operands. An under-
voltage element, auxiliary contacts of breakers indicating close position, or other elements can be useful for no-current
supervision.
• WEAK-INFEED PICKUP DELAY: This setting delays operation of weak-infeed keying during some transient condi-
tions (such as breaker reclosure, etc.).
• WEAK-INFEED RESET DELAY: The weak-infeed keying function incorporates a default 35 ms reset delay to assure
reset coordination with the FDH trip-level fault detector at the remote terminal during fault clearing. The default reset
time can be changed according to local conditions.
5-84 L60 Line Phase Comparison Relay
5 SETTINGS
GE Multilin