GE L60 Instruction Manual page 270

5.5 GROUPED ELEMENTS
• 87PC FDH PICKUP: This setting is used to select FDH pickup value. FDH is used as a trip-arming element.
• 87PC FDH AUX: This setting assigns an auxiliary element (an impedance element, for example) in parallel with FDH
to permit tripping. This is beneficial for power system conditions where FDH cannot pick up.
• 87PC FDH SUPV: This setting assigns an auxiliary element (an impedance element, for example) to seal-in the FDH
output for 200 ms to prevent another FDH operation during external fault clearing.
• 87PC CH1 ASYMMETRY and 87PC CH2 ASYMMETRY: These settings set the symmetry adjustment to make posi-
tive and negative halves of the power cycle of the received signal from the remote terminal via communication channel
noise symmetrical. Refer to the test procedures for more detailed information.
• 87PC CH1 DELAY and 87PC CH2 DELAY: These settings delay the local signal until the remote signal is received.
Refer to the test procedures for more detailed information.
• 87PC CH1 RX VOLT and 87PC CH2 RX VOLT: These settings select a threshold for the signal received from the car-
riers. They are dependent on the carrier nominal output voltage. A value of 10 to 20% of carrier nominal output voltage
is recommended.
• 87PC TRIP SECURITY: This setting controls security of the response of the 87PC function on the first and following
coincidence periods. When set to "First Coincidence" the function uses the primary
operates when the integrated value exceeds the setting. Each coincidence period is treated independently. When set
to "Enhanced", the function applies the value for the first coincidence period specified by
setting. If the integrated value is less than this more stringent stability angle setting, the function does not trip. If the
integrated value is greater than the regular stability angle setting, but less than the enhanced trip level, the function
arms itself toward tripping on the next coincidence. The regular stability angle value specified by the
setting controls tripping on the next coincidence.
ANGLE
• 87PC SECOND COINCID TIMER: This setting applies only if the
5
specified time opens a window for tripping on the second coincidence if the first coincidence does not satisfy the more
stringent stability angle setting. This value is typically set to 1.25 cycles in dual comparison applications and 2 cycles in
single comparison applications.
• 87PC STABILITY ANGLE: This setting is used to select the stability angle for trip security.
• 87PC ENHANCED STAB ANGLE: This setting specifies the more stringent stability angle allowing the scheme to trip
safely on the first coincidence. This setting applies only if the
ting is typically 30° to 40° higher than the regular stability angle specified by the
The enhanced trip security is illustrated below. In part a) of the figure, tripping occurs at the first coincidence if the inte-
grator exceeds the enhanced stability angle setting. In part b), tripping occurs at the second coincidence if at the first
coincidence integrator exceeded the stability angle setting but did not reach the enhanced stability angle setting.
5-138
87PC TRIP SECURITY
87PC TRIP SECURITY
L60 Line Phase Comparison System
5 SETTINGS
setting and
87PC STABILITY ANGLE
87PC ENHANCED STAB ANGLE
87PC STABILITY
mode is set to "Enhanced". The
mode is set to "Enhanced". This set-
setting.
87PC STABILITY ANGLE
GE Multilin