GE Multilin L60 Line Phase Comparison Relay 2-12 PRODUCT DESCRIPTION 2.1 INTRODUCTION22 PRODUCT DESCRIPTION 2.1INTRODUCTION 2.1.1 OVERVIEWThe L60 Line Phase Comparison Relay provides a simple phase-comparison principle successfully employed by analogand static relays for many years along with the significant advantages of a modern microprocessor based relay. The phasecomparison element performs the following calculations:• Samples and filters three-phase AC currents at a rate of 64 samples per cycle.• Computes sequence components of the current.• If two CT/VT modules are employed for breaker-and-a-half applications, the relay sums up two currents and performsthe breaker-and-the-half logic calculations.• Forms a composite signal from current components according to a user-defined setting.• Forms local positive and negative squares from the composite signal sent to remote terminal and used locally alongwith the channel delay value.• Samples received from remote terminal squares 64 samples per cycle measuring magnitude of the pulse voltage.• Processes received samples to compensate for asymmetry and distortions in the signal.• Detects fault condition with the fault detector.• Compares coincidence of local and remote squares which indicate the presence of internal or external faults.• Detects transient conditions to block the phase comparison function.All processed signals, including transmitted and received pulses, are available in oscillography for commissioning, mainte-nance, and analysis. The L60 integrates received pulses on a sample-per-sample base, similar to the analog phase-com-parison principle, making the relay exceptionally robust on noisy channels. All permissive and blocking schemes, as well assingle and dual phase comparison, are incorporated into a single protection element and can be selected with a relay set-ting. The L60 supports two and three-terminal applications, can be used for single- and three-pole tripping applications, andsupports breaker-and-a-half applications. Multiple backup functions include three-zone phase and ground distance, direc-tional overcurrent, pilot schemes, and current and voltage elements.Control features include synchrocheck, autoreclosure, and control for two breakers. Monitoring features include CT failuredetector, VT fuse failure detector, breaker arcing current, disturbance detector and continuous monitor.Diagnostic features include an event recorder capable of storing 1024 time-tagged events, oscillography capable of storingup to 64 records with programmable trigger, content and sampling rate, and data logger acquisition of up to 16 channels,with programmable content and sampling rate. The internal clock used for time-tagging can be synchronized with an IRIG-B signal or via the SNTP protocol over the Ethernet port. This precise time stamping allows the sequence of events to bedetermined throughout the system. Events can also be programmed (via FlexLogic™ equations) to trigger oscillographydata capture which may be set to record the measured parameters before and after the event for viewing on a personalcomputer (PC). These tools significantly reduce troubleshooting time and simplify report generation in the event of a sys-tem fault.A faceplate RS232 port may be used to connect to a PC for the programming of settings and the monitoring of actual val-ues. A variety of communications modules are available. Two rear RS485 ports allow independent access by operating andengineering staff. All serial ports use the Modbus ® RTU protocol. The RS485 ports may be connected to system computerswith baud rates up to 115.2 kbps. The RS232 port has a fixed baud rate of 19.2 kbps. Optional communications modulesinclude a 10Base-F Ethernet interface which can be used to provide fast, reliable communications in noisy environments.Another option provides two 10Base-F fiber optic ports for redundancy. The Ethernet port supports IEC 61850, Modbus ® /TCP, and TFTP protocols, and allows access to the relay via any standard web browser (L60 web pages). The IEC 60870-5-104 protocol is supported on the Ethernet port. DNP 3.0 and IEC 60870-5-104 cannot be enabled at the same time.Typical two and three-terminal applications are shown below.