2-2 L30 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUALPRODUCT DESCRIPTION CHAPTER 2: PRODUCT DESCRIPTION2Secure Routable GOOSE (R-GOOSE) is supported with software options.In addition to current differential protection, the relay provides multiple backup protection for phase and ground faults. Forovercurrent protection, the time overcurrent curves can be selected from a selection of standard curve shapes or acustom FlexCurve™ for optimum co-ordination.The L30 incorporates charging current compensation for applications on very long transmission lines without loss ofsensitivity. The line capacitive current is removed from the terminal phasors.For breaker-and-a-half or ring applications, the L30 design provides secure operation during external faults with possibleCT saturation.Voltage, current, and power metering is built into the relay as a standard feature. Current parameters are available as totalwaveform RMS magnitude, or as fundamental frequency only RMS magnitude and angle (phasor).The L30 uses flash memory technology that allows field upgrading as new features are added. Firmware and software areupgradable.The following single-line diagram illustrates the relay functionality using American National Standards Institute (ANSI)device numbers.Table 2-1: ANSI device numbers and functions supportedDevice number Function Device number Function25 Synchrocheck 51_2 Negative-sequence time overcurrent27P Phase undervoltage 52 AC circuit breaker27X Auxiliary undervoltage 59N Neutral overvoltage49 Thermal overload protection 59P Phase overvoltage50BF Breaker failure 59_2 Negative-sequence overvoltage50DD Current disturbance detector 59X Auxiliary overvoltage50G Ground instantaneous overcurrent 67N Neutral directional overcurrent50N Neutral instantaneous overcurrent 67P Phase directional overcurrent50P Phase instantaneous overcurrent 79 Automatic recloser50_2 Negative-sequence instantaneous overcurrent 81R Rate of change frequency51G Ground time overcurrent 81U Underfrequency51N Neutral time overcurrent 87L Segregated line current differential51P Phase time overcurrent 87LG Line ground current differential
