GE L90 Instruction Manual page 242

5.5 GROUPED ELEMENTS
d) 87L TRIP
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PATH: SETTINGS GROUPED ELEMENTS
# 87L TRIP
#
5
The 87L Trip element must be used to secure the generation of tripping outputs. It is especially recommended for use in all
single-pole tripping applications. It provides the user with the capability of maintaining the trip signal while the fault current
is still flowing, to choose single-pole or three-pole tripping, to employ the received Direct Transfer Trip signals, to assign
supervising trip elements like 50DD, etc. The logic is used to ensure that the relay will:
• trip the faulted phase for a single line to ground fault, as detected by the line differential element
• trip all three phases for any internal multiphase fault
• trip all three phases for a second single line to ground fault during or following a single pole trip cycle
For maximum security, it is recommended the Disturbance Detector (plus other elements if required) be assigned to see a
change in system status before a trip output is permitted. This ensures the relay will not issue a trip signal as a result of
incorrect settings, incorrect manipulations with a relay, or inter-relay communications problems (for example, extremely
noisy channels). The Open Pole Detector provides forcing of three-pole tripping for sequential faults and close-onto-fault if
desired. The Open Pole Detector feature must be employed and adequately programmed for proper operation of this fea-
ture. The
87L TRIP 1P OP
If DTT is not required to cause the 87L Trip scheme to operate, it should be disabled at the remote relay via the
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ETTINGS GROUPED ELEMENTS
menu.
NOTE
TIAL
• 87L TRIP FUNCTION: This setting is used to enable/disable the element.
• 87L TRIP SOURCE: This setting is used to assign a source for seal-in function.
• 87L TRIP MODE: This setting is used to select either three-pole or single-pole mode of operation.
• 87L TRIP SUPV: This setting is used to assign a trip supervising element. The
mended (the element has to be enabled); otherwise, elements like instantaneous overcurrent, distance, etc. can be
used.
• 87L TRIP FORCE 3-φ: This setting is used to select an element forcing 3-pole tripping if any type fault occurs when
this element is active. Autoreclosure Disabled can be utilized, or Autoreclosure Counter if second trip for example is
required to be a 3-pole signal, or element representing change in the power system configuration, etc. can be consid-
ered to be applied.
5-152
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SETTING GROUP 1(6)
87L TRIP FUNCTION:
Disabled
87L TRIP SOURCE:
MESSAGE
SRC 1
87L TRIP MODE:
MESSAGE
3-Pole
87L TRIP SUPV:
MESSAGE
Off
87L TRIP FORCE 3-φ:
MESSAGE
Off
87L TRIP SEAL-IN:
MESSAGE
Disabled
87L TRIP SEAL-IN
MESSAGE
PICKUP: 0.20 pu
87L TRIP TARGET:
MESSAGE
Self-reset
87L TRIP EVENTS:
MESSAGE
Disabled
and operands are provided to initiate single-pole or three-pole autoreclosing.
87L TRIP 3P OP
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SETTING GROUP 1(6)
L90 Line Differential Relay
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SUPERVISING ELEMENTS
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4
Range: 3-Pole, 1-Pole
Range: FlexLogic™ operand
Range: FlexLogic™ operand
Range: Disabled, Enabled
Range: 0.20 to 0.80 pu in steps of 0.01
Range: Self-reset, Latched, Disabled
Range: Disabled, Enabled
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LINE DIFFERENTIAL ELEMENTS
FlexLogic™ operand is recom-
50DD SV
5 SETTINGS
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87L TRIP
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CURRENT DIFFEREN-
GE Multilin