GE L60 Instructions Manual

Also see for L60: Communications manual Communications guide Instruction manual Instruction manual Instruction manual

Contents

CHAPTER 5: SETTINGS GROUPED ELEMENTSL60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUAL 5-1955the majority of faults—the overlap between the space periods and positive peaks of the voltage in the phase used by thecarrier. Normally, this angle shall be adjusted to follow the conductor used by the carrier plus the extra line characteristicangle (approximately 90°).The following setting rule applies particularly for blocking schemes.Table 5-25: Setting ruleSome 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 insituations that are not concerned with the corona effect, this setting does not alter operation of the relay: neither improvesit, nor impairs it. The only effect is in possibly different operating times for different fault types, with the average timesunchanged.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 startchannel 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 topermit 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 outputfor 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 andnegative halves of the power cycle of the received signal from the remote terminal via communication channel noisesymmetrical. 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 testprocedures for more information.87PC CH1 RX VOLT and 87PC CH2 RX VOLT — These settings select a threshold for the signal received from the carriers. Theyare dependent on the carrier nominal output voltage. A value of 10 to 20% of carrier nominal output voltage isrecommended.87PC TRIP SECURITY — This setting controls security of the response of the 87PC function on the first and followingcoincidence periods. When set to “First Coincidence” the function uses the primary 87PC STABILITY ANGLE setting andoperates 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 integratedvalue is greater than the regular stability angle setting, but less than the enhanced trip level, the function arms itselftoward tripping on the next coincidence. The regular stability angle value specified by the 87PC STABILITY ANGLE settingcontrols tripping on the next coincidence.87PC SECOND COINCID TIMER — This setting applies only if the 87PC TRIP SECURITY mode is set to “Enhanced.” The specifiedtime opens a window for tripping on the second coincidence if the first coincidence does not satisfy the more stringentstability angle setting. This value is typically set to 1.25 cycles in dual comparison applications and 2 cycles in singlecomparison applications.87PC STABILITY ANGLE — This setting is used to select the stability angle for trip security.Ref angle setting Phase rotation, ABC Phase rotation, ACBCarrier 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 ofentirely diminishing security and/or dependability. The same caution applies to the scheme type, operating current,and K settings.