ABB REM54 motor terminal troubleshooting

ABB REM54 motor terminal troubleshooting

Introduction: REM54 is not a regular feeder protection, troubleshooting should first look at the overall integrity of the "machine terminal"

ABB REM 543 and REM 545 belong to the REM 54_ series of rotating machine terminals, aimed at small and medium-sized diesel, hydropower, steam turbine generators and generator transformer units. They are also used for starting and operating protection of large and medium voltage synchronous motors and asynchronous motors such as pumps, fans, mills, crushers, etc. Unlike feeder protection, REM54 integrates protection, control, measurement, status monitoring, PLC logic, and communication into one device. Analog inputs can be connected to conventional current/voltage transformers or ABB's Rogowski coils and voltage dividers. The device also has a virtual simulation channel, which calculates neutral current and residual voltage using phase current and phase voltage.

When there is a "motor start trip", "generator differential misoperation", "grounding protection not working", "reclosing/control command failure", or "communication interruption" on site, it is not enough to only check one set value. The troubleshooting of REM54 should follow the sequence of "first check the self-test and power supply, then verify the analog input and sensors, then check the protection function and differential/grounding logic, and finally check the control, communication, and whole machine replacement". Special attention should be paid to the fact that the components of REM54 are calibrated together with the entire machine, and the documentation clearly states that spare parts are not provided separately. In the event of a malfunction, the supplier should be consulted, and it is not possible to replace only one board like a regular plug-in.

First, check the self-test, power supply, and temperature: Ready light flashing and IRF code are first-hand information

REM54 has a relatively complete self checking system that monitors RAM, ROM, parameter storage, CPU watchdog, power supply, digital I/O module, HMI module, RTD/analog input module, internal communication bus, A/D converter, and analog multiplexer. When an internal fault is detected, the green Ready indicator light starts flashing, and the HMI displays a fault text. At the same time, the self-test output relay acts and locks the protection trip output. At this point, you should first read the IRF fault code in the main menu, record the fault type, and then decide whether to power off for inspection. Do not reset repeatedly directly, otherwise the fault information may be lost.

In terms of power supply, REM54 requires reliable auxiliary voltage. PS1/240V supports 110/120/220/240V AC or 110/125/220V DC; PS1/48V supports 24/48/60V DC. The power module has a low auxiliary voltage indication: when the power supply voltage is about 10% lower than the minimum rated DC input of the power module, the internal ACFail signal will activate. This signal can be connected to any signal output in the configuration. If there are "repeated device restarts", "Ready light abnormality", or "protection indefinite lockout" on site, the auxiliary power supply ripple, instantaneous interruption, and battery voltage should be checked. The document provides auxiliary DC interruption time: less than 50ms at 110V and less than 100ms at 200V should not be reset; If the actual interruption exceeds this range, the power circuit and backup power supply should be checked.

REM54 also has internal overheating monitoring, which sends an overheating signal when the temperature inside the casing rises to about+78 ° C (+75...+83 ° C). If the temperature inside the cabinet is high in summer and the device frequently reports overheating, the ventilation inside the cabinet, filter blockage, and installation spacing should be checked instead of adjusting the protection settings.

Analog input and sensor: the part most likely to be "wrongly connected" in REM54 troubleshooting

REM54 has two analog input schemes based on hardware versions: hardware number REM54x_xxxAAAA/CAAA/AAAB is configured as a matching transformer; REM54x_xxxAABA/CAAB/AABB is configured to match transformer and sensor inputs. The sensor input can be connected to Rogowski coils or voltage dividers, and connected through shielded dual BNC connectors. Unused sensor inputs must be short circuited with dedicated connectors, otherwise interference or measurement abnormalities may be introduced.

The conventional transformer scheme should verify the CT/VT ratio, polarity, star point grounding, and secondary load. The sensor scheme should verify the sensor direction, shielding layer grounding, connector fastening, and channel scaling factor. Each analog channel of REM54 can be individually set with a scaling factor, where 1.00 indicates that the rated value of the protected equipment is consistent with the rated value of the measuring equipment; If the CT/VT ratio or sensor ratio is not consistent with the device settings, there will be systematic deviations in overcurrent, differential, impedance, and power protection.

REM54 also has a virtual simulation channel for calculating neutral current and residual voltage under the sensor scheme. Special reminder in the document: When sensitive grounding fault protection is required, it is not recommended to replace the core balanced CT with phase currents added up by numerical values. Usually, when the grounding setting value is lower than 10% of the rated value, the core balanced CT should be used. If there is a "small current grounding fault does not trip" or "frequent misoperation of grounding protection" on site, it is necessary to first confirm whether it is a dedicated zero sequence CT or a numerical calculation channel, and then check the setting value and wiring. Using three-phase summation to calculate zero sequence is prone to distortion under CT saturation, interference, or unbalanced loads, and cannot be regarded as a universal substitute.

Protection function troubleshooting: overcurrent, voltage controlled overcurrent, differential, under excitation, and low impedance

The protection function blocks of REM54 are independent of each other, with fixed value groups and data records. Typical current protection can be achieved using Rogowski coils or conventional CTs, while voltage protection can be achieved using voltage dividers or VT. When troubleshooting, it is necessary to first confirm whether the function block is activated, whether the set value group is correct, whether the measurement mode is peak or fundamental, and whether the trip output is self checked or externally locked.

Overcurrent and voltage control overcurrent. NOC3Low/High/In is used for three-stage non directional overcurrent; DOC6Row/High/In is used for directional overcurrent; VOC6Low/High is a voltage controlled overcurrent that supports voltage step, voltage slope, or input step control, and can reduce the starting current multiple at low voltages. If the motor malfunctions due to overcurrent during startup, the voltage limit, current multiplier, and startup time of VOC should be checked; If it refuses to move during a short circuit, check the starting current, time multiplier, measurement mode, and CT ratio. For directional overcurrent, it is also necessary to check the basic angle φ b, direction forward/reverse, and voltage wiring.

Differential protection. REM54 provides Diff6G stable generator differential, Diff3 high impedance or magnetic balance generator/motor differential, and REF1A high impedance restricted earth fault. The core of differential troubleshooting is CT polarity, transformation ratio, secondary wiring, and stable resistance/stable parameters. Diff6G has basic fixed values, start-up ratios, inflection points of 1/2, and transient periods; Diff3 has a basic fixed value and delay. If there is a fault differential misoperation outside the area, it should be checked whether the CT polarity is uniform, whether the differential CT has the same transformation ratio, whether the stable resistance is configured according to the calculation, and whether the secondary circuit is grounded at multiple points. If the fault in the area refuses to operate, the differential current threshold, braking characteristics, and CT saturation should be checked. High impedance differential also requires checking external stability resistors and metal oxide varistors.

Underexcitation and low impedance. UE6Row/High is under excitation protection, using impedance circle characteristics, and can set center offset, circle diameter, top distance from the R axis, and measurement mode. UI6Low/High is a three-phase low impedance protection with a Z setting of 0.01... 60 p.u., which can be used as a backup for the line. If there is an under excitation misoperation, the PT voltage, CT polarity, circular characteristic parameters, and measurement mode should be checked; If the impedance is low and refuses to move, the Z setting, phase selection, and voltage/current circuit should be checked.

Thermal overload, negative sequence, and frequency. TOL3Dev is used for thermal overload of motors, generators, and transformers, and requires selection of equipment type, starting current, allowable starting time, cold start frequency, ambient temperature, cooling/heating time constant, and restart suppression temperature. If the motor frequently trips, check whether the equipment type is selected incorrectly, whether the ambient temperature sensor is connected, and whether the time constant is consistent with the manufacturer's data. NPS3Low/High is used for negative sequence overcurrent and requires setting negative sequence startup value, time constant K, cooling time, and phase number. Freq1St1... 5 is used for underfrequency/overclocking and df/dt, and can be set with undervoltage lockout. If the frequency protection malfunctions, check whether the voltage amplitude is lower than the lockout value and whether the frequency measurement is affected by the frequency converter interference.

Power and start-up supervision. OPOW6St1... 3 is directional over power, UPOW6St1... 3 is under power/reverse power, and power direction, starting power, delay, and measurement mode need to be set. MotStart is used for motor start supervision and supports I ² t, I ² t&Tall. It can record the number of starts, allowed restart time, and locked rotor input. If the motor fails to start but the thermal protection is not activated, the starting current, allowed starting time, restart suppression, and stall signal of MotStart should be checked.

Control, tripping circuit monitoring and status monitoring: cannot only focus on protection tripping

The control functions of REM54 include circuit breaker control, isolation switch control, three state isolation switch, object indication, MIMIC dynamic data point, alarm channel, On/Off switch, and logic control position selector. The control function must be associated with the MIMIC configuration of the HMI, otherwise it cannot be correctly indicated and operated locally. If the on-site "protection action but circuit breaker does not trip", in addition to checking the protection trip output, it is also necessary to check the HSPO/PO/SO output type, control circuit power supply, auxiliary contacts, and trip circuit monitoring.

CMTCS1/CMTCS2 is a trip circuit monitoring system that monitors the integrity of the trip circuit based on constant current injection. If a tripping circuit fault is reported, the tripping coil, auxiliary contacts, terminal block, control voltage, and monitoring circuit current should be checked. CMCU3/CMVO3 monitoring excitation current/voltage input circuit; CMBWEAR1/2 monitors the electrical wear of circuit breakers; CMTIME1/2 is an operation time counter; CMTRAV1 is the travel time of the circuit breaker; CMSCHED is for regular maintenance; CMGAS1/3 is for gas pressure monitoring. The status monitoring data should be viewed in conjunction with event records and waveform recordings, rather than just looking at individual alarms.

The digital input is voltage controlled, optically isolated, can be reversed, and the filtering time can be set; Partial digital inputs can be programmed as pulse counters with a frequency range of 0... 100Hz. Digital outputs are divided into HSPO high-speed power output, PO power output, and SO signal output. HSPO bipolar contacts are suitable for tripping and circuit breaker control; SO is a common signal contact and cannot control heavy loads such as circuit breakers. If the control command is intermittent, check whether the output type is selected incorrectly, whether the contact capacity is sufficient, and whether the digital input filtering and oscillation suppression are too strong.

Communication and configuration: SPA, LON, Modbus, and external display

REM54 has three serial ports: front panel optical port RS232 for PC configuration, using SPA bus; The rear X3.2 is a 9-pin RS232 with optional SPA or Modbus RTU/ASCII; The rear X3.3 is a 9-pin RS485, with optional SPA or LON options. Fiber optic isolation requires RER123 (SPA) or RER103 (SPA/LON). Modbus requires a third-party fully isolated RS232/RS485 converter, and the documentation lists the Phoenix converter and dedicated cable. X3.4 is RJ45, used for external display modules, and the external display module requires independent auxiliary voltage from the same source as the host.

Communication troubleshooting should start with the physical layer: fiber optics, connectors, converter power supply, baud rate; Link layer: address, protocol selection, master-slave settings; Final application layer: event table, parameter table, SCADA point table. If the LON interlock does not work, check the LON network variable binding and LNT configuration; If Modbus cannot read data, the protocol selection, converter isolation, and cable should be checked. The configuration tools include CAP501/CAP505, Relay Configuration Tool, Relay Mimic Editor, and LON Network Tool. The parameters can be set locally on the HMI or externally on CAP501 or SMS510. After replacing the device, it is necessary to re download the configuration and settings, and verify the MIMIC, alarm LED, event, and communication mapping.

Whole machine replacement: REM54 cannot only replace one board

The REM54 document clearly states that in order to ensure operational accuracy, all components are calibrated together, and the product is considered as a whole and no spare parts are provided separately; When there is a malfunction, the supplier should be contacted. When replacing or modifying, one should not only look at the "REM543/REM545" model, but also verify the complete order number. The order number identifies the machine type, software version, functional level (M motor/G generator), hardware number, auxiliary power supply (A is PS1/240V, C is PS1/48V), sensor/transformer input (A has no sensor, B has a sensor), and display (A fixed display, B external display module). The display language is determined by the software number suffix, such as 001 English German, 002 English Swedish, 003 English Finnish, 009 English Russian. The Modbus option also needs to be confirmed according to the order, and some information is only marked as REM543.

Before replacement, the number of digital inputs and outputs should be checked (REM543 is 15 DI, REM545 is 25 DI; TCS input is 2; Whether there are RTD/analog modules, whether there are 4 channels of 0... 20mA analog outputs, whether sensor inputs need to be short circuited, external display module cables and auxiliary power supplies, communication modules and protocols. After replacement, secondary injection, differential polarity, and trip transmission should be performed TCS、 Verify point-to-point communication and HMI MIMIC. The configuration of the old device cannot be directly applied to the new hardware number, otherwise the sensor/transformer input and I/O mapping may be inconsistent.

On site troubleshooting checklist

Ready light flashes and IRF code appears. Record the IRF code, check the power supply, self-test module, I/O and RTD modules, ensure that the protection trip is locked, and do not forcefully put them into operation.

The analog quantity has a large deviation. Check the CT/VT ratio, sensor ratio, channel scaling factor, whether unused sensor inputs are short circuited, shielded, and grounded.

Misoperation outside the differential zone. Check CT polarity, transformation ratio, stable resistance, secondary multi-point grounding, Diff6G/Diff3/REF1A constant value, and braking characteristics.

Low current grounding does not trip. Check if a core balanced CT is used; it is not recommended to use three-phase summation as a substitute for sensitive grounding below 10% of the rated value.

The motor starts and trips. Check VOC voltage control, TOL3Dev device type and time constant, MotStart startup supervision, startup frequency, and restart suppression.

Trip circuit alarm. Check the CMTCS1/2 constant current monitoring circuit, trip coil, auxiliary contacts, control voltage, and terminals.

Communication interruption. Check the front panel/rear ports RER123/RER103、 Converter, protocol, baud rate, LON binding, and Modbus point table.

Complete machine replacement. Verify the complete order number, hardware number, power supply, sensor/transformer input, display language, Modbus options, and I/O quantity; Replace and recalibrate the test.