The Low-Voltage Motor Protector is a new-generation comprehensive protector developed by our company for various fault characteristics of low-voltage circuit motors. It is a low-voltage protection device that offers high cost-performance, stability, and reliability, integrating relay protection, measurement, control, and communication. The protector features a split structure, consisting of the main body, display module, and current transformer. It replaces thermal relays, thermal protectors, leakage protectors, under-voltage protectors, and eliminates time relays, intermediate relays, auxiliary relays, meters, control and selection switches, indicator lights, programmable controllers, transmitters, and various additional components, significantly simplifying the complexity of system wiring. It prevents production accidents caused by motor overloading, stalling, phase failure, unbalanced three-phase current, over/under voltage, and leakage. This device is suitable for AC 50Hz, system voltage 380V/660V (default 380V), rated current 800A and below. For larger motors, control and protection can be achieved through a 5A special transformer in conjunction with a primary/5A protective transformer. It is widely used in industries such as power, petrochemical, light industry, coal, paper, iron and steel, metallurgy, and textiles.
Product Features
Comprehensive electrical parameter measurements, including voltage, current, power, zero sequence/current leakage, temperature, positive/negative sequence current, electrical energy, power factor, heat capacity, voltage/current percentage, average current, and voltage/current unbalance values, etc.
A comprehensive motor protection function covering short circuit, overflow, blockage, stall, overload, overcurrent, underload, phase loss, voltage/current imbalance, grounding (zero sequence/leakage), external faults, extended startup time, overvoltage, undervoltage, underpower, overpower, startup count, trip count, operation timeout, phase sequence, temperature, phase failure, voltage drop restart, anti-sag, tE time, etc.
Features 2-way analog output, conveniently converting motor measurement values (current, voltage, power, zero sequence, temperature, heat capacity, etc.) into 4-20mA DC current, thereby achieving the functions of a conventional fully isolated transmitter.
A full range of control methods is available, including pure protection, direct start, autotransformer reduction start, star-delta start, forward-reverse start, and two-speed start. Simply setting up allows for easy transition between different control function logic, offering high flexibility and versatility.
Equipped with a system clock and SOE timestamping function, it can record protective operations, specific action values, and action times, as well as remote signal change events, start-up information, and stop information, with up to hundreds of related data records. These can be uploaded or viewed on-site, providing a robust basis for fault diagnosis and accident analysis.
Configured with 10-wire switch input (passive), offering versatile state and command signal functionalities, allowing for normally open or normally closed signals. Features 6 relay output functions, with customizable outputs that can be set to normally open or normally closed, and adjustable output expansion time. Options for automatic fault return or manual return are available.
Equipped with motor management and maintenance functions, recording the motor's start-up current, historical start-up current, running current, historical running current, start-up count, tripping count, cumulative total running time, total stoppage time, current running time, and current stoppage time.
Features comprehensive self-check capabilities, including memory, outputs, indicators, communication ports, etc., and can automatically alert to any device anomalies.
Features 2-way remote communication capability, utilizing RS-485 communication interface, and operates with the standard MODBUS-RTU protocol.
Universal Input Power Module, compatible with AC or DC power sources ranging from 85-265V, reduces requirements for working power supply.
Widely used in coal mining, petrochemical, smelting, power, pump, fan, and construction industries.
Feature Configuration
Type Feature | Feature Configuration | ||||
| Standard Features | Optional features | ||||
| Protection Feature | Short circuit, overflow | √ | |||
| Blockage, jamming | √ | ||||
| Overload, Overcurrent | √ | ||||
| Underloaded, phase missing | √ | ||||
| Voltage and current unbalance | √ | ||||
| External Fault | √ | ||||
| Boot-up time too long | √ | ||||
| Overvoltage, undervoltage | √ | ||||
| Overpower, Underpower | √ | ||||
| Startup Count | √ | ||||
| Number of trips | √ | ||||
| Operation Time-Out | √ | ||||
| Phase sequence, phase displacement | √ | ||||
| Temperature | √ | ||||
| Residual Current | Grounding (Self-produced) | √ | |||
| Grounding and leakage protection must be selected from one. | Leakage | √ (Leakage) | |||
| T/T (Telegraphic Transfer) Time | √ Enhanced Safety Protection | ||||
| Loss-of-voltage restart function (anti-surge) | √ | ||||
| Control Method | Protect Start Mode | √ | |||
| Direct Start Mode | (Select one) | ||||
| Two-speed start mode | |||||
| On-off reverse start mode | |||||
| Star-Delta Start Mode | |||||
| Self-coupled step-down starting mode | |||||
| Soft Starter with Start-up Mode | |||||
| Variable Frequency Drive with Start-up Mode | |||||
| Communication Features | RS485 Interface Communication Protocol: MODBUS-RTU | √ (Communication Function) | |||
| Switched Input | 10-way DI, compatible with various starting methods | √ | |||
| Relay Output | 6-way DO, compatible with various starting methods | √ | |||
| Analog Output | DC4-20mA | √ (Analog Function) | |||
| Data Recording | 50 event records, detailing the causes and times of motor failures | √ | |||
| Measurement shows | Measurement Parameters | Three-phase line voltage, power, power factor | √ | ||
| Electric Power | √ | ||||
| Three-phase current, frequency | √ | ||||
| Setpoint configuration | Setpoint setting | Various Protection Setpoint Queries | √ | ||
| Various protective setpoint settings | √ | ||||
Technical Specifications
| Technical Specifications | Key Technical Specifications | |
| Operating Power Supply | AC/DC 85~265V, power consumption 8VA, less than 0.75VA per phase | |
| Rated working voltage for motor | AC 380V (660V upon order, please specify) 50Hz | |
| Rated operating current of the motor | Utilize an external dedicated current transformer that matches the motor's rated current, with 2 times the rated current for continuous operation and up to 10 times the rated current for 10 seconds. | |
| Relay Output Contact Rating | Resistive Load | AC250V、5A；DC30V、5A |
| Switched quantity input | Dry Contact (Built-in DC15V) | |
| Communication | RS485 Modbus-RTU Protocol | |
| Environmental | Operating Temperature | -20ºC～+55ºC |
| Storage Temperature | -25ºC～+70ºC | |
| Relative Humidity | ≤95% non-condensing, non-corrosive gases | |
| Elevation | ≤3000m | |
| A0 Output | Load Capacity: Less than 750Ω, Accuracy: ±0.5% | |
| Accuracy | Level 1, Action Time: ±80ms ±3% | |
| Ingress Protection (IP) Rating | Main IP20, Separate IP45 (when installed on cabinet panel) | |
Dimensions and wiring diagram
Body module size (35mm track mounting and M4 bolts)
Display Module Dimensions (Flush Mount)
Subject Terminal Diagram
