GE L60 Instruction Manual

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

Contents

5-128 L60 Line Phase Comparison System GE Multilin5.5 GROUPED ELEMENTS 5 SETTINGS5– 3TL-TR-SPC-2FC: three-terminal line, permissive tripping scheme, single phase comparison, two frequencychannel carrier to two other terminals.– 3TL-BL-SPC-2FC: three-terminal line, blocking scheme, single phase comparison, two frequency channel carrierto two other terminals.– 3TL-TR-DPC-3FC: three-terminal line, permissive tripping scheme, dual phase comparison, three frequencychannel carrier to two other terminals.– 3TL-BL-SPC-3FC: three-terminal line, blocking scheme, dual phase comparison, three frequency channel carrierto two other terminals.A two-frequency channel (2FC) can be either amplitude modulated (AM) on-off carrier or a high-low frequencyshift keying (FSK) system.In blocking schemes, the open breaker echo element must be disabled. Additional information about phasecomparison can be found in the Theory of operation chapter.• 87PC BLOCK: Selects a Flexlogic operand that blocks operation of the phase comparison scheme (for example, anoperand that indicates operation of a communications channel failure detector).• 87PC SIGNAL SOURCE: Selects whether current is supplied from one current source (either single-breaker CT appli-cation or dual-breakers with CTs summed externally) or from two separate sources (breaker-and-a-half or ring configu-rations), where currents from both CTs are fed into the L60 individually.• 87PC SIGNAL: A mixed I_2 – K × I_1 signal, mixed I_1+I_2 / K signal, or single 3I_0 signal can be chosen as theoperating signal for the FDH and FDL detectors and positive/negative square pulses generation. The constant K in themixed excitation signal is adjustable.• 87PC MIXED SIGNAL K: Selects the K factor used in the mixed excitation operating signals I_2 – K × I_1 andI_1+I_2 / K. For the mixed I_1+I_2 / K mode, the setting range is limited from 0.08 to 0.25.• 87PC MIXED SIGNAL REF ANGLE: This setting applies exclusively to the negative-sequence mixed mode operatingcurrent (“Mixed I_2-K*I_1”) and specifies a leading angular shift for the originally developed operating signal. The oper-ating signal is always developed taking phase A as reference for calculating symmetrical components. This setting canbe used to control the angular position of the operating current with respect to the voltage of any phase that might beused by the line carrier in a particular application. This allows minimizing the impact of positive corona on dependabilityof single-comparison blocking schemes. Effectively this setting shifts the transmitted pulses in time with the intent tominimize – for majority of faults – the overlap between the space periods and positive peaks of the voltage in the phaseused by the carrier. Normally, this angle shall be adjusted to follow the conductor used by the carrier plus the extra linecharacteristic angle (approximately 90°).The following setting rule applies particularly for blocking schemes:Some applications are not concerned with the corona effect, such as when the applied carrier uses narrow-band filter-ing, 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. Ifused in situations that are not concerned with the corona effect, this setting will not alter operation of the relay: neitherimproves it, nor impairs it. The only effect would be in possibly different operating times for different fault types, with theaverage times unchanged.This setting must be set identically at all line terminals or the scheme will be dramatically impacted to theextent of entirely diminishing security and/or dependability. The same caution applies to the scheme type,operating current, and K settings.• 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 tostart channel keying. This is beneficial for power system conditions when FDL cannot pick up.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°NOTENOTENOTE