GE L90 Instruction Manual page 361

5 SETTINGS
c) 87L TRIP
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PATH: SETTINGS GROUPED ELEMENTS
 87L TRIP
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MESSAGE
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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 (DTT) signals, and to
assign supervising trip elements like the disturbance detector. 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 and
87L TRIP 1P OP
If a direct transfer trip (DTT) is not required for the 87L trip scheme to operate, it should be disabled at the remote
relay via the
GROUPED ELEMENTS
settings menu.
NOTE
TIAL
• 87L TRIP FUNCTION: This setting is used to enable or 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-: This setting is used to select an element forcing three-pole tripping if any type fault occurs
when this element is active. Autoreclosure disabled can be utilized, or the autoreclosure counter if, for example, the
second trip is required to be a three-pole signal. Likewise, any operand representing a change in the power system
configuration, can be applied.
GE Multilin

SETTING GROUP 1(6)
87L TRIP FUNCTION:
Disabled
87L TRIP SOURCE:
SRC 1
87L TRIP MODE:
3-Pole
87L TRIP SUPV:
Off
87L TRIP FORCE 3-:
Off
87L TRIP SEAL-IN:
Disabled
87L TRIP SEAL-IN
PICKUP: 0.20 pu
87L TRIP TARGET:
Self-reset
87L TRIP EVENTS:
Disabled
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 Current Differential System
5.6 GROUPED ELEMENTS
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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

LINE DIFFERENTIAL ELEMENT
FlexLogic™ operand is recom-
50DD SV
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87L TRIP
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CURRENT DIFFEREN-
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