ABB RET620 Transformer Protection and Control IED (Relion 620 Series) Complete Description
I. Product Basic Positioning
RET620 is an ABB Relion® 620 series dedicated transformer protection and control intelligent device (IED), specifically designed for double-winding / triple-winding power transformers, step-up transformers, generator-transformer units, and is integrated with protection, measurement, control, voltage regulation, fault recording, and communication remote transmission. It is widely used in substations, factory self-owned power distribution, and power plant step-up stations.
Similar series distinctions:
REF620 = Feeder Protection
REM620 = Motor Protection
RET620 = Transformer Protection (cannot be used interchangeably)
Core Protection Functions (ANSI Standards)
1. Main Protection (Differential)
Proportional braking transformer differential protection (87T) + Differential Instantaneous Trip, with secondary / fifth harmonic braking, perfectly avoiding transformer excitation surge, preventing surge mis-tripping;
Automatically completes CT ratio, transformer connection group (Y/Δ) phase compensation, suitable for most distribution transformers;
Can detect winding inter-turn short circuits, bushing flashover, phase-to-phase short circuit faults, with fast action.
2. Ground Fault Protection
Optional high impedance / low impedance restricted ground protection REF (87REF), accurately detecting winding internal ground faults;
Zero-sequence overcurrent, zero-sequence overvoltage protection, covering high and low voltage side ground abnormalities.
3. Backup Protection
Three-stage overcurrent on high and low voltage sides (50/51), direction overcurrent (67), voltage locked overcurrent;
Overexcitation protection (V/Hz), preventing overvoltage causing core saturation and burning the transformer;
Thermal overload protection (double time constant), simulating transformer temperature rise curve, over-temperature alarm / trip;
Low voltage, overvoltage, high/low frequency, negative sequence imbalance protection;
Optional RTD temperature measurement expansion: monitoring winding, oil temperature, bearing temperature, Pt100 temperature measurement.
4. Special Extended Functions
OLTC On-load Voltage Control AVR: directly controls on-load tap changer, automatically regulates voltage to stabilize bus voltage, the voltage regulation logic is integrated in the device, no additional voltage regulation controller required;
Optional Arc Flash Protection: detects internal arc in switch cabinet, millisecond-level trip to enhance equipment personnel safety;
Breaker failure protection, interlock closing and opening, isolating switch / grounding switch operation control.
Measurement and Event Recording Capability
Real-time collection of three-phase current, voltage, active/reactive power, power factor, frequency, load current;
Fault recording: can export COMTRADE waveforms, used for post-tripping analysis;
SOE Event Sequence Record with millisecond-level timestamp, traceable reasons for tripping sequence;
Support 6 groups of switch setting value groups, suitable for different operating modes.
Communication Capability (Strong Adaptation to Digital Substation)
Core standards: IEC61850 Ed1/Ed2, supports GOOSE trip message, SMV sampling values, HSR/PRP dual network redundancy, IEEE1588 time synchronization;
Compatible with traditional protocols: IEC60870-5-103, Modbus RTU/TCP, DNP3;
Panel-mounted large-screen graphic LCD, can customize primary wiring single-line diagram; supports web-based HMI, direct browser login to view data, modify parameters;
Configuration and debugging software: PCM600, used for setting value upload/download, firmware upgrade, fault log reading;
Expandable RIO600 remote I/O module, expand input/output points.
Hardware Structure and Installation Characteristics Pull-out module design: The cabinet can be pre-wired in advance. Subsequent insertion and replacement of the device does not require disassembling the secondary wiring, making operation and maintenance convenient;
Panel buttons + local operation, allowing on-site closing and opening, viewing alarms, and resetting faults;
Wide power supply range, compatible with DC operation power supply of substations;
The protection level is suitable for embedded installation of switch cabinets, and electromagnetic compatibility meets the strict EMC standards of the power industry.
Typical application scenarios
10kV/35kV main transformer protection and control in the distribution room of industrial and mining enterprises;
Generator – main transformer unit protection in power plants;
Transformer protection in photovoltaic/wind power substation;
Renovation of old substations with comprehensive protection, and digital transformation of intelligent substations in accordance with IEC61850.
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