CHAPTER 5: SETTINGS
GROUPED ELEMENTS
L60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUAL
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the majority of faults—the overlap between the space periods and positive peaks of the voltage in the phase used by the
carrier. Normally, this angle shall be adjusted to follow the conductor used by the carrier plus the extra line characteristic
angle (approximately 90°).
The following setting rule applies particularly for blocking schemes.
Table 5-25: Setting rule
Some applications are not concerned with the corona effect, such as when the applied carrier uses narrow-band filtering,
or similar techniques improving security and dependability of transmission.
Shifting the angle reference is considered an advanced principle and does not have to be used in all applications. If used in
situations that are not concerned with the corona effect, this setting does not alter operation of the relay: neither improves
it, nor impairs it. The only effect is in possibly different operating times for different fault types, with the average times
unchanged.
87PC FDL PICKUP
— This setting is used to select the FDL pickup value. FDL is used as a start-keying element.
87PC FDL AUX
— This setting assigns an auxiliary element (an impedance element, for example) in parallel with FDL to start
channel keying. This is beneficial for power system conditions when FDL cannot pick up.
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 positive and
negative halves of the power cycle of the received signal from the remote terminal via communication channel noise
symmetrical. See the test procedures for more information.
87PC CH1 DELAY
and
87PC CH2 DELAY
— These settings delay the local signal until the remote signal is received. See the test
procedures for more information.
87PC CH1 RX VOLT
and
87PC CH2 RX VOLT
— These settings select a threshold for the signal received from the carriers. 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
87PC STABILITY ANGLE
setting and
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
87PC ENHANCED STAB ANGLE
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
87PC STABILITY ANGLE
setting
controls tripping on the next coincidence.
87PC SECOND COINCID TIMER
— This setting applies only if the
87PC TRIP SECURITY
mode is set to “Enhanced.” The 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.
Ref angle setting
Phase rotation, ABC
Phase rotation, ACB
Carrier in phase A
90°
90°
Carrier in phase B
240° + 90° = 330°
120° + 90° = 210°
Carrier in phase C
120° + 90° = 210°
240° + 90° = 330°
This setting must be set identically at all line terminals or the scheme is dramatically impacted to the extent of
entirely diminishing security and/or dependability. The same caution applies to the scheme type, operating current,
and K settings.
