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L60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUAL
GROUPED ELEMENTS
CHAPTER 5: SETTINGS
5
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
87PC TRIP SECURITY
mode is set to “Enhanced.” This setting is typically
30° to 40° higher than the regular stability angle specified by the
87PC STABILITY ANGLE
setting.
The figure illustrates enhanced trip security. In part a) of the figure, tripping occurs at the first coincidence if the integrator
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.
Figure 5-98: Enhanced trip security
87PC PICKUP DELAY
— This setting specifies a pickup delay for the phase comparison element. This delays the start of the
coincidence detection by specified time. It does not affect start of the signal transmittal to the remote terminal.
87PC STOP TX
— This setting selects a FlexLogic operand that is used to stop signal transmittal to the remote terminal. This
can be used in blocking schemes to accelerate tripping at the remote end and in tripping schemes to prevent tripping at
the remote end, if desirable.
87PC TX RESET DELAY
— This setting specifies a time delay to prolong signal transmission to the remote end after FDL drops
off and is recommended for blocking schemes only. If mixed current is greater than 0.02 pu, then square pulses are
transmitted. If mixed current is less than 0.02 pu, then continuous blocking signal are transmitted for blocking schemes.
87PC RESET DELAY
— This setting is used to seal-in the output phase comparison element after operating by the time
defined by this setting. A value of 30 ms or higher is recommended. A value of 0 ms operates the element during integrated
coincidence only, meaning that the 87PC OP output operand is set and reset on every cycle.
87PC TRANS BLOCK PICKUP
— This setting increases sensitivity during and after the clearing of an external fault and prevents
false tripping during transient current intervals. If a pickup delay is used, the this setting must be increased by the time
specified in the
87PC PICKUP DELAY
setting.
87PC TRANS BLOCK RESET
— Resets transient blocking and allows tripping.
87PC CHNL LOSS TRIP WINDOW
— This setting is applicable to the 2TL-UB-DPC-2FC scheme only. If a loss of carrier is
detected in the course of the fault, a trip is allowed for the time defined by this setting (default value is 0). The trip is blocked
after the expiration of this time window.
87PC HIGH-SPEED CONTACT 1
and
87PC HIGH-SPEED CONTACT 2
— These settings allow decreasing of the tripping time by up
to one-quarter of the power cycle by bypassing FlexLogic execution and sending trip command directly from the 87PC
function to the contact output. These setting are used for breaker 1 and 2 (if used) trip coil connections.