GE L90 Instruction Manual page 16

PRODUCT DESCRIPTION
IEC 61850, Modbus/TCP, TFTP, and PTP (according to IEEE Std. 1588-2008 or IEC 61588), and it allows access to the relay via
any standard web browser (L90 web pages). The IEC 60870-5-104 protocol is supported on the Ethernet port. The Ethernet
port also supports the Parallel Redundancy Protocol (PRP) of IEC 62439-3 (clause 4, 2012) when purchased as an option.
Secure 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. For
overcurrent protection, the time overcurrent curves can be selected from a selection of standard curve shapes or a
custom FlexCurve™ for optimum co-ordination. Additionally, five zones of phase and ground distance protection with
2
power swing blocking, out-of-step tripping, line pickup, load encroachment, and six pilot schemes are included.
The L90 incorporates charging current compensation for applications on very long transmission lines without loss of
sensitivity. The line capacitive current is removed from the terminal phasors.
For breaker-and-a-half or ring applications, the L90 design provides secure operation during external faults with possible
current transformation (CT) saturation.
Voltage, current, and power metering are built in as standard features. Current parameters are available as total
waveform RMS magnitude, or as fundamental frequency only root mean square (RMS) magnitude and angle (phasor).
Settings and actual values can be accessed from the front panel or EnerVista software.
The L90 uses flash memory technology that allows field upgrading as new features are added. Firmware and software are
upgradable.
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 supported
Device number Function
21G Ground distance
21P Phase distance
24 Volts per hertz
25 Synchrocheck
27P Phase undervoltage
27X Auxiliary undervoltage
32N Wattmetric zero-sequence directional
32R Sensitive reverse power
49 Thermal overload protection
50BF Breaker failure
50DD Adaptive fault detector
(sensitive current disturbance detector)
50G Ground instantaneous overcurrent
50N Neutral instantaneous overcurrent
50P Phase instantaneous overcurrent
50_2 Negative-sequence instantaneous overcurrent
51G Ground time overcurrent
51N Neutral time overcurrent
51P Phase time overcurrent
2-2
CHAPTER 2: PRODUCT DESCRIPTION
Device number Function
51_2 Negative-sequence time overcurrent
52 AC circuit breaker
59C Compensated overvoltage
59N Neutral overvoltage
59P Phase overvoltage
59X Auxiliary overvoltage
67N Neutral directional overcurrent
67P Phase directional overcurrent
67_2 Negative-sequence directional overcurrent
68 Power swing blocking
78 Out-of-step tripping
79 Automatic recloser
81O Overfrequency
81R Rate of change of frequency
81U Underfrequency
87RGF Restricted ground fault
87L Segregated line current differential
87LG Ground line current differential
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL