ABB REF620 (Relion 620 series) feeder protection and measurement device

ABB REF620 (Relion 620 series) feeder protection and measurement device

Product positioning: Why REF620 is suitable for feeder protection and renovation projects

ABB REF620 is a feeder protection and control IED in the Relion 620 series, designed for the protection, control, measurement, and monitoring of utility and industrial distribution systems. It is suitable for radial, ring network, and mesh distribution networks, and can be configured with various switchgear configurations such as single bus or double bus, single circuit breaker or double circuit breaker. For existing renovation projects, the value of REF620 lies not only in its "multiple protection functions", but also in its extractable unit design, expandable functionality, support for IEC 61850, and two default configurations of traditional CT/VT and sensor input, making it easy to choose between different cabinet types and measurement schemes.

REF620 provides two default configurations: Configuration A uses traditional current and voltage transformer inputs; Configuration B uses current and voltage sensor inputs. The default configuration can be used as the starting point of the project, but it cannot be directly applied as the end user. On site application configuration, signal matrix configuration, and parameter tuning still need to be done through PCM600. For replacing or adding feeder protection devices, the first step is to verify whether the existing cabinet is a CT/VT or sensor solution, and then determine the hardware variants, I/O quantities, and communication modules of REF620 to avoid discovering a mismatch in wiring methods only after arrival.

Protection function and setting points: from overcurrent to ground fault

The protection functions of REF620 cover a wide range, including three-stage non directional overcurrent, directional overcurrent, non directional grounding fault, directional grounding fault, negative sequence overcurrent, phase failure protection, residual voltage protection, three-phase undervoltage/overvoltage, positive sequence undervoltage, negative sequence overvoltage, frequency protection, thermal overload, circuit breaker failure, surge detection, main tripping, etc. commonly used on site. For networks where the neutral point is not grounded, grounded through resistance, or grounded through impedance, admittance type, harmonic type, wattmeter type grounding fault protection, as well as transient/intermittent grounding fault protection, can also be selected.

Don't just look at the parameters of a single machine during calibration. Overcurrent protection should be combined with the rated current of the feeder, CT ratio, cable current carrying capacity, and the coordination of upper and lower level protection; Grounding fault protection should be combined with neutral point grounding method, zero sequence CT transformation ratio, and on-site capacitive current. Directional overcurrent and directional grounding faults require confirmation of the polarity, wiring group, and directional mode of the voltage transformer. For overhead lines that require reclosing, the coordination between automatic reclosing and overcurrent/ground fault protection should be checked to avoid reclosing with permanent faults. REF620 supports multi instance protection function. When configuring the project, the purpose of each instance should be clearly defined in PCM600 to avoid duplicate or missing configurations.

Control, Interlocking, and HMI: On site operations cannot rely solely on indicator lights

REF620 supports circuit breaker control, isolation switch control, and grounding switch control, and provides corresponding position indications. Each controllable device typically requires two binary inputs and two binary outputs, depending on the selected hardware configuration. If there is insufficient I/O, remote I/O expansion can be achieved through RIO600, but non fast signals should be allocated to external I/O while retaining fast tripping and critical interlock signals of the main body.

The local HMI includes an LCD, 11 programmable LEDs, and 16 configurable manual buttons, supporting local/remote switching. During on-site debugging, it should be confirmed that the indication of the opening and closing position of the circuit breaker is consistent with the actual state; The position signals of the isolation switch and grounding switch are correct; Interlocking logic is implemented through signal matrix or application configuration; The LED and button functions are consistent with the single line diagram. For renovation projects, it is not enough to only check the protection settings, but also the control circuit, auxiliary contacts, trip circuit, and signal circuit. Otherwise, there may be problems such as "protection action but circuit breaker not tripped" or "background display inconsistent with actual position".

Measurement, power quality and recording functions: data foundation for troubleshooting

REF620 can measure three-phase current, zero sequence current, three-phase voltage, zero sequence voltage, and calculate sequence components, frequency, active/reactive power, power factor, electrical energy, and current/power demand. In terms of power quality, it supports monitoring of total current demand distortion, total voltage harmonic distortion, voltage variation, and voltage imbalance. For fault analysis, the device provides disturbance records, fault records, event records, and load curves. Disturbance records can be configured with up to 12 analog channels and 64 binary channels; Event records can store 1024 time stamped events; The fault record can save 128 latest fault events.

When troubleshooting on site, these records are more valuable than "doing the experiment again". For example, after the feeder trips, the fault current, voltage, protection start and trip signals in the fault record should be read first, and then combined with disturbance recording to determine whether it is overcurrent, grounding fault or circuit breaker failure. If the backend only sees "protection actions" without specific stages, the event records and GOOSE signal mapping should be checked. The load curve is suitable for judging long-term overload, load fluctuations, and abnormal demand, and it is not advisable to draw conclusions based on a single instantaneous value.

Communication networking: IEC 61850, Modbus, DNP3 and redundancy selection

REF620 supports IEC 61850, IEC 60870-5-103, Modbus, and DNP3. IEC 61850 supports horizontal GOOSE communication and can be used to protect inter trip, interlocking, and analog transmission; Modbus supports RTU, ASCII, and TCP; DNP3 supports both serial port and TCP. The device can run protocols such as IEC 61850 and Modbus simultaneously, making it easy to connect to different backends.

There are three common ways of redundant networking: PRP, HSR, and RSTP self-healing ring. PRP operates in parallel with two independent networks, with zero switching time; HSR sends two frames in a single loop, transmitted in opposite directions. It is recommended to have no more than 30 HSR loops for 620 series IEDs; The RSTP self-healing ring is implemented through a management switch, which has a lower cost, but the switching time is not as good as PRP/HSR. When selecting on-site, the backend architecture, switch capabilities, and project budget should be taken into account, and fiber optic interfaces, communication modules, and switch configurations should not be ignored for the sake of "full redundancy". During debugging, the communication module type, fiber/electrical port, baud rate, IP address, GOOSE dataset, and subscription relationship should be checked. If GOOSE is disconnected, first check the physical link and switch configuration, and then check the dataset and APPID.

Input/Output and Expansion Modules: Hardware Checklist that must be verified before replacement

The basic configuration of traditional CT/VT variants includes 3 phase current inputs, 1 residual current input, 3 phase voltage inputs, 1 residual voltage input, and 1 phase synchronous check voltage input. The basic configuration consists of 24 binary inputs and 14 binary outputs. The sensor variant includes 3 sensor inputs (RJ-45 combiner) and retains 1 traditional residual current input, with a basic configuration of 16 binary inputs and 14 binary outputs. Residual current input can be selected as 0.2/1A, suitable for sensitive ground fault protection.

Optional modules include: BIO0005 adds 8 binary inputs and 4 binary outputs; BIO0007 provides 8 binary inputs and 3 high-speed outputs, with a high-speed output startup time of about 1ms, suitable for fast applications such as arc protection; RTD0003 provides 6 RTD inputs and 2 mA inputs. When replacing or expanding, the slot position, module type, terminal definition, and ordering code should be checked. Special attention should be paid to the fact that the terminals of high-speed output boards are different from those of ordinary BIO modules, and orders cannot be placed simply by looking at "a few more I/Os". The type of power supply should also be checked, commonly including 48-250VDC/100-240VAC and 24-60VDC.

On site debugging and common troubleshooting

1. Check before powering on. Check the power supply voltage, polarity, fuse, grounding, CT secondary short circuit, VT secondary not short circuit, sensor wiring and shielding. Confirm that the CT/VT ratio inside the cabinet is consistent with the device parameters. For extractable units, check if the CT automatic short-circuit contacts are reliable.

2. Self check and alarm. REF620 has a self check function that continuously monitors the status of hardware and software. If the HMI shows a self-test alarm, the alarm code and LED status should be recorded first, and then the power supply, communication module, I/O module, and firmware version should be checked. Do not simply reset it, otherwise you may lose fault information.

3. Trip circuit monitoring. Trip circuit monitoring can monitor the availability of the circuit breaker in both closed and open positions, and can detect loss of control voltage. If a "trip circuit fault" is reported, the trip coil, auxiliary contacts, terminal block, fuse, and control voltage should be checked. For double trip coils, they should be verified separately.

4. Monitoring of fuse failure. This function detects voltage measurement circuit faults through negative sequence algorithm or voltage/current change rate, and locks the voltage dependent protection after action to prevent misoperation. If the fuse failure is reported, the VT secondary fuse, air switch, and voltage terminal should be checked.

5. Current circuit monitoring. Current circuit monitoring compares the sum of CT three-phase currents with the reference current to detect CT secondary circuit faults. If there is an abnormality in the current circuit, the CT terminal, short circuiting piece, transformer ratio, and secondary load should be checked.

6. Communication abnormality. If the backend communication is interrupted, first check the physical layer: network cable/fiber optic cable, switch port, communication module indicator light; Recheck the link layer: IP address, subnet VLAN； Finally, check the application layer: IEC 61850 dataset, GOOSE subscription, Modbus register mapping. For PRP/HSR, the dual network configuration and redundant box status should be confirmed.

7. Unable to reset after protective action. Check the trip hold, circuit breaker mechanism, auxiliary contacts, closing interlock, and reclosing logic. If the protection has been reset but the circuit breaker cannot be closed, the control circuit and interlocking conditions should be checked instead of repeatedly pressing the closing button.

Replacement and maintenance suggestions

When replacing REF620 or using it for old cabinet renovation, it is recommended to establish a "four-dimensional checklist": mechanical dimensions and installation methods, electrical input and output and CT/VT/sensor types, communication protocols and redundancy methods, ordering codes and certification documents. REF620 supports flush, semi flush, rack mounted, wall mounted, and 19 inch installation. The panel opening size is 162 ± 1mm high and 248 ± 1mm wide. Before replacing, the old device opening, terminal height, and depth should be measured to confirm the space inside the cabinet.

When migrating parameters, do not only migrate protection settings. Control logic, GOOSE configuration, LED mapping, event recording settings, and communication parameters should be migrated simultaneously. Before operation, secondary injection test, trip transmission, interlock test, point-to-point communication test, and background signal verification should be completed. During the maintenance cycle, self inspection records, trip circuit monitoring status, event records, and load curves should be regularly checked, and maintenance should be arranged based on the number of circuit breaker actions and fault current levels.

The reliability of REF620 is based on correct selection, wiring, and configuration. If on-site engineers can string "hardware verification - protection setting - communication networking - fault record analysis" into a closed loop, it can significantly shorten power outage time in feeder protection modification, fault investigation, and daily operation and maintenance, and improve the observability and maintainability of the distribution system.