Description
REX521GHHGSH51G REX521 ABB module
REX521GHHGSH51G multifunctional feeder/motor comprehensive protection relay pure text introduction
1、 Product basic positioning
REX521GHHGSH51G belongs to the REX521 series high-end microcomputer protection device, which integrates protection, measurement, control, fault recording, and equipment monitoring functions. It is mainly aimed at medium voltage distribution systems, suitable for feeders, large and medium-sized three-phase AC motors, and can also be used as backup protection for transformers and high voltage lines. It is compatible with various distribution networks such as neutral point ungrounded, resonant grounded, resistance grounded, and directly grounded, and supports single bus primary circuit configuration for radiation network and ring network. The model code GHHGSH51G corresponds to high-end hardware versions, glass fiber optic communication, dedicated power supply specifications, extended I/O, Chinese operation interface, and feeder standard protection program configuration. This series of products has been discontinued and only spare parts are available in the market. The new generation replacement model is the 615 series comprehensive protection device.
REX521GHHGSH51G REX521 ABB module
2、 Hardware structure and human-machine interface
The whole machine adopts a standard cabinet embedded installation structure, with a protection level of IP20, and is only suitable for internal layout of switchgear.
The front panel is equipped with two rows of 16 character LCD screens, matched with four-way navigation buttons, confirmation and exit operation buttons; The panel is equipped with multiple sets of status LED indicator lights to distinguish between protection actions, alarms, device operation, fault lockout, circuit breaker position, and other statuses. Real time electrical quantities, fault records, and set parameters can be viewed locally without the need for an upper computer.
The rear terminals are divided into three main modules: analog input terminals, switch input/output terminals, and communication and power supply terminals. The analog circuit is compatible with conventional electromagnetic current and voltage transformers, supporting 1A/5A secondary current and 100V secondary voltage access; This model of hardware also reserves access channels for Roche coils and electronic sensors. The switch circuit includes multiple passive inputs and relay passive tripping/alarm outputs. The output contacts can carry 24V DC to 250V AC circuit breaking and have online monitoring function for tripping circuit disconnection.
The communication hardware is equipped with dual independent communication channels, one RS485 electrical interface and one glass fiber optic interface, supporting multiple remote control protocols such as SPA, Modbus RTU, DNP3.0, and IEC60870-5-103. The fiber optic channel can avoid industrial strong electromagnetic interference and extend the communication wiring distance. The device comes with hardware timing input and supports minute/second pulse synchronization. When there is no external synchronization, the internal clock drift can be controlled to meet the unified recording requirements of substation fault timing.
3、 Complete protection function configuration
Current protection
Three stage interphase overcurrent protection, distinguishing between definite time and inverse time action characteristics; Three stage zero sequence grounding protection, supporting directional grounding fault discrimination, suitable for low current grounding systems; Built in excitation surge suppression logic to avoid protection misoperation during transformer and motor startup; Thermal overload protection, simulating the cumulative heating curve of equipment to achieve long-term overload warning and tripping; Phase failure, three-phase imbalance, negative sequence current protection, to deal with motor phase loss and winding asymmetry faults.
Voltage and frequency protection
Overvoltage, low voltage, and zero sequence overvoltage protection; Frequency over limit and frequency slip protection; Phase sequence error and voltage imbalance monitoring, suitable for photovoltaic and generator grid connected circuits.
Special motor matching protection
Motor start-up timeout monitoring, locked rotor protection, rotor current blocking lockout; Configurable acceleration logic before and after reclosing, suitable for rapid fault removal of domestic distribution network lines.
Auxiliary backup protection
Circuit breaker failure protection, CT disconnection alarm, PT disconnection alarm; Independent zero sequence voltage grounding fault identification; Can be used as backup overcurrent protection for main transformers and high-voltage lines.
4、 Measurement, recording and monitoring functions
High precision electrical measurement
Real time collection of three-phase current, three-phase line voltage, phase voltage, zero sequence current, and zero sequence voltage; Calculate active power, reactive power, apparent power, power factor, and frequency; Accumulate positive and negative active and reactive energy, record extreme current demand, and support monitoring of harmonic distortion in power quality.
Fault recording function
Built in transient fault recorder, automatically stores multi cycle current and voltage waveforms before and after the fault is triggered, synchronously records the timing of protection startup, tripping, and switch displacement, facilitating post fault traceability analysis. The storage records can be retrieved locally or uploaded to the backend system.
Equipment status monitoring once
Count the number of electrical wear and tear of circuit breakers and evaluate the degree of contact aging; Real time monitoring of the integrity of the trip control circuit; Collect position signals of isolation switches and grounding switches to achieve electrical interlocking logic; Customize multiple alarm signals, distinguish between minor alarms and emergency trip signals for graded output.
5、 Communication and system integration capability
The dual communication channels can independently connect to the local debugging computer and the substation backend monitoring system. The fiber optic channel is suitable for long-distance, strong interference factory areas, and outdoor distribution room scenarios. Support remote fixed value modification, remote signal retrieval, and remote fault recording download; Capable of GOOSE type signal interaction, able to achieve inter compartment protection logic linkage; The internal multi processor architecture of the device ensures independent operation of protection operations, measurement, and communication tasks, and a single channel failure does not affect the protection trip logic.
6、 Applicable working environment and electrical parameters
The working environment temperature range is from minus 20 degrees Celsius to plus 70 degrees Celsius, and it can withstand temperature changes inside industrial switchgear; The whole machine is equipped with electrical isolation, and the analog, switch, and communication circuits are isolated from each other. The anti electromagnetic interference meets the standards of the power industry.
The power supply supports wide range AC/DC universal input and is compatible with commonly used operating power sources in substations; The whole machine is designed with low power consumption, with low heat generation during long-term operation and no need for additional cooling devices.
The supporting I/O can increase the input and output points through external expansion units to meet the control requirements of complex primary circuits with multiple switches and interlocks.
7、 Typical application scenarios
Medium voltage distribution incoming and outgoing line spacing, radiation network, and ring network line protection in urban and industrial plant areas;
Complete protection for large and medium-sized medium voltage three-phase AC motors such as water pumps, fans, rolling mills, and air compressors;
Low voltage side backup protection for distribution transformers and remote backup overcurrent protection for high-voltage lines;
Integrated measurement and control protection interval for small substations, box transformers, and outdoor switch stations;
Accurate identification scenarios for cable line grounding faults in resonant grounding and low resistance grounding systems.
8、 Basic fault simple judgment logic
Running indicator light off: device power loss, internal hardware failure;
The protection action red light is always on: overcurrent, grounding, abnormal voltage and other faults trigger tripping, and the fault type, fault current and voltage values can be retrieved from the panel;
CT/PT disconnection alarm light on: voltage transformer, current transformer secondary circuit disconnection or short circuit;
Communication link interruption: fiber optic connector contamination, loose RS485 bus wiring, mismatched backend communication parameters;
Trip circuit alarm: The circuit breaker’s opening coil is disconnected and the control power supply is missing.
