HighPROTEC MRM4, MRMV4 protection of LV and MV induction motors
HighPROTEC MRM4 and MRMV4 are protection terminals for low and medium voltage induction motors of any rating. The first model protects the motor by current, the second adds voltage, frequency and power protections. The start recorder logs currents, start duration and the thermal capacity used.
- Application
- low and medium voltage induction motors of all ratings
- MRM4
- current-based protections
- MRMV4
- protections by current and voltage, power, frequency; 4 analog outputs (type B)
- Motor functions
- thermal overload 49M, locked rotor 51LRS, jam 51LR, underload 37, start 48, number of starts 66, asymmetry 46, overcurrent 50P/51P, earth fault 50N/51N, lockout 86
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
MRM4 and MRMV4 from the HighPROTEC line are built on a dual-core processor. MRM4 works on current measurement, monitors the start sequence, detects rotor locking and jamming, and tracks the thermal state of the motor. MRMV4 also has voltage inputs, so power, frequency and voltage protections are added to the current protections, along with underload and incomplete start monitoring. The functions are adapted to VDE-AR-N 4110:2023-09, and MRM4 has Lloyd’s Register marine approval.
The basic set of motor protections includes thermal overload (49M), locked rotor during start (51LRS), jam or locking during running (JAM, 51LR), underload (37), start monitoring (48) and a limit on the number of starts per hour (66). Current asymmetry is tracked by negative sequence protection (46). There are overcurrent and instantaneous protection (50P/51P), earth fault protection (50N/51N) and restart lockout (86). In the -2B versions the temperature is monitored through an external RTD unit (26). MRMV4 has wattmetric earth fault protection, six overcurrent stages, four earth fault stages, two zero sequence voltage stages, four voltage stages, six frequency stages, six power stages, two power factor stages, maximum value recording and THD protection.
For heavy starts there are extended start with reduced voltage starting, emergency start, incomplete sequence monitoring, a reverse rotation delay, a permissible number of cold starts and mechanical unloading. The relay sees zero speed through a digital input, and separate inputs are provided for stop and external signals. MRM4-2B has a 20 mA analog output, and MRMV4-B has four analog outputs. The start recorder logs maximum currents, negative sequence currents, start duration, the number of successful starts, the thermal capacity used and the temperature profile. History counters count starts, trips, operating time and circuit breaker wear. System supervision covers breaker failure protection (50BF), the trip circuit (74TC) and current transformers (60).
Communication is via Modbus, Profibus, DNP3.0, IEC 61850, IEC 60870-5-103 and IEC 60870-5-104 with individual data point assignment, time is synchronized via SNTP and IRIG-B, and cybersecurity functions are provided. Non-volatile recorders store waveforms for 120 s, 20 faults, 300 events and a trend of 4000 records. Smart view and waveform analysis are supplied at no extra charge under the all-inclusive concept. Typical applications are motors of pumps, fans, compressors, mills and conveyors in power generation, water supply, the oil and gas industry and mining.
Technical specifications
| Application | low and medium voltage induction motors of all ratings |
|---|---|
| MRM4 | current-based protections |
| MRMV4 | protections by current and voltage, power, frequency; 4 analog outputs (type B) |
| Motor functions | thermal overload 49M, locked rotor 51LRS, jam 51LR, underload 37, start 48, number of starts 66, asymmetry 46, overcurrent 50P/51P, earth fault 50N/51N, lockout 86 |
| Temperature | external RTD unit (MRM4-2B, MRMV4-2B) |
| Start recorder | max. currents, duration, thermal capacity used |
| Marine approval | Lloyd’s Register (MRM4) |
Request a price and lead time
HighPROTEC MRM4, MRMV4 protection of LV and MV induction motors. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Customs codes
| UKTZED (Ukraine) | 8537 10 98 00 |
|---|---|
| HS, 6 digits | 8537 10 |
| CN (EU) | 8537 10 98 |
| HTSUS (USA) | 8537 10 91 70 |
| China customs tariff | 8537 10 90 90 |
Codes are for reference: the final code is determined at declaration for the specific model.
Questions and answers
How does MRMV4 differ from MRM4?
MRM4 works on current measurement. MRMV4 also measures voltage, has power, frequency and voltage protections, underload monitoring and four analog outputs in the B version.
Does the relay limit the number of motor starts?
Yes, function 66 limits the number of starts per hour, and the permissible number of cold starts is set separately. The start recorder logs the thermal capacity used.
Can temperature sensors be connected to MRM4?
Yes, in the -2B versions the temperature is monitored through an external RTD unit (function 26). MRM4-2B also has a 20 mA analog output.
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