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

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.