Overview
The ARD2F series is Acrel’s intelligent motor protector designed for low-voltage motor circuits up to 660V.
Featuring a split structure (main unit + display unit + CTs), it integrates protection, measurement, control, communication, and maintenance functions.
Comprehensive protection ensures safe motor operation, programmable logic supports multiple control modes, and various communication modules are available for fieldbus adaptation.
With full-wave/fundamental parameter measurement, event logging/SOE, and anti-sag restart function, it serves as the intelligent upgrade terminal for conventional motor circuits.
Highlight
Cost-Effective & Practical
- Integrates protection, measurement, and control, covering 30+ protection functions. Standard 2 DO, 9 DI, flexible options, suitable for most LV motor applications.
Comprehensive Protection
- Overload, stall, jam, underload, phase loss, unbalance, OV/UV, ground/leakage, temperature, tE time, etc. Fully configurable thresholds/delays/stages.
Anti-Sag & Continuous Production
- Optional undervoltage restart (anti-sag) function, supports instant and delayed restart, effectively copes with voltage dips and ensures production continuity.
Flexible Programming & Multi-Protocol
- Fully programmable DI/DO, logic diagram; supports 1~2 MODBUS RTU, PROFIBUS DP, custom address mapping, compatible with various control systems.
Focus Areas
Overload, stall, tE time protection for large motors, preventing burn-out and reducing unplanned downtime.
Underload protection for pumps, runtime alarm, predictive maintenance, lower O&M costs.
Reversing & two-speed control, suitable for frequent start/stop and heavy-load conditions, enhancing equipment reliability.
Ex motor tE time protection, leakage/ground fault protection for hazardous areas.
MODBUS/PROFIBUS access to PLC/DCS for motor energy monitoring, remote diagnosis, and centralized management.
Specification
| Item | Parameter |
| Auxiliary Power | AC85~265V / DC100~350V |
| Motor Rated Voltage | AC220V / 380V / 660V, 50/60Hz |
| Motor Rated Current | 1A / 5A / 1.6A / 6.3A / 25A / 100A / 250A / 800A (external CT, 1A/5A versions support CT ratio up to 5000A) |
| Relay Output Contact Rating | Resistive load: AC250V, 10A |
| Digital Input | 9 channels, dry contact (optional wet contact DC110V/DC220V/AC220V) |
| Analog Output | Optional 1 channel DC4~20mA |
| Communication | RS485 Modbus_RTU (standard 1 port, optional 2 ports) Profibus_DP (optional) |
| Environment | Operating Temp: -10℃～55℃ Storage Temp: -25℃～70℃ Relative Humidity: ≤95% non-condensing, non-corrosive Altitude: ≤2000m |
| Pollution Degree | Class 2 |
| Protection Rating | Main unit: IP20 Display module (panel mounted): IP65 |
| Installation Category | Class III |
| Mounting | 35mm DIN rail |
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Function
| Protection Function | Standard | Optional |
| Definite-time overload | √ | |
| Inverse-time overload | √ | |
| Start timeout | √ | |
| Phase loss | √ | |
| Voltage unbalance | √ | |
| Current unbalance | √ | |
| Stall | √ | |
| Jam | √ | |
| Underload | √ | |
| External fault | √ | |
| Temp. protection | √ | |
| Ground fault (residual) | √ | |
| Leakage | √ | |
| Phase sequence | √ | |
| Undervoltage | √ | |
| Overvoltage | √ | |
| Underpower | √ | |
| Overpower | √ | |
| tE time (Ex motor) | √ | |
| Overflow | √ | |
| Start count alarm | √ | |
| Runtime alarm | √ | |
| Fault count alarm | √ |
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| Control Mode | Standard | Optional |
| Protection mode | √ | |
| Manual mode | √ | |
| Two-step mode | √ | |
| Two-speed mode | √ | |
| Star-delta | √ | |
| Auto-transformer | √ | |
| Anti-sag restart | √ |
| Measurement/Logging | Standard | Optional |
| U/I | √ | |
| P/Q/S | √ | |
| PF, F | √ | |
| EP/EQ | √ | |
| Events log | √ | |
| Trend log | √ |
Core Monitoring & Protection Functions
- Monitoring: 3-phase current/voltage (fundamental+full-wave), line voltage, zero/pos/neg sequence components, unbalance, P/Q/S, PF, F, energy, leakage current, PTC/NTC resistance, thermal capacity, residual current.
- Protection/Alarm: Inverse-time overload, definite-time overload, stall, jam, underload, phase loss, current unbalance, voltage unbalance, over/under voltage, phase sequence, over/under power, short circuit, overflow, ground fault, leakage, PTC/NTC temp, external fault, start timeout, tE time, start count, runtime, fault count.
- Control: Local start/stop (LCD keys/DI), remote control via communication, programmable logic, anti-sag restart (instant/undervoltage restart), two-speed/star-delta/auto-transformer starting modes.
- Precise Metering: Voltage/current accuracy Class 0.5, active energy Class 1.
Summary
The Acrel ARD2F intelligent motor protector is an ideal replacement for traditional thermal relays, integrating protection, measurement, control and communication into a compact split-body structure. Through the integration of programmable protection settings, logic control and multiple communication protocols, it upgrades passive motor protection to proactive warning and precise metering. Whether for standard low-voltage motors or Ex increased-safety motors, ARD2F provides reliable and cost-effective protection — an intelligent entry-level choice for industrial motor management.
FAQ
ARD2F natively supports Protection mode (external pushbuttons). With optional “Q” start control, it supports Manual mode (LCD/DI direct start/stop), as well as Two-step (star-delta), Two-speed, and Auto-transformer modes (with external contactors). All control modes can be switched via DI or remote communication.
The tE time protection function is optional. Set “Motor type” to “Ex increased-safety” in protection parameters; the “Trip class” will automatically switch to tEp setting (2~15s). Select the trip class according to the motor nameplate tE time. Under locked-rotor current, the protector will trip according to the tE characteristic curve, ensuring power-off before reaching the temperature limit.
Yes. DO4 and DO5 are factory-set as trip outputs, but users can redefine them via the “Programmable Settings” menu to any function such as start, stop, alarm, fault, etc., and configure NO/NC, pulse duration, etc. When the 5-DO option is selected, DO1~DO3 are also fully programmable.
Yes. Both start control (Q) and undervoltage restart (SU) options must be selected. You can configure “instant restart” (0.1~10s) and “undervoltage restart” (delay restart after voltage drops below set value). Ideal for production lines requiring high power supply continuity.
Both PTC (Positive Temperature Coefficient) and NTC (Negative Temperature Coefficient) thermistors are supported. The temperature protection (T) option must be selected. Select the sensor type in protection parameters, set alarm/trip thresholds and return resistance. Suitable for motor winding and bearing temperature monitoring.
Select the 1A or 5A current version of the protector, use external high-ratio CTs (e.g., 2500/5A), and set the “CT ratio” parameter (1~5000). The primary current can be extended up to 5000A. The displayed values will automatically reflect the actual primary current.
Standard cable length is 1.5m (Ethernet cable), with optional 3m and 5m lengths. For reliable communication, the maximum recommended length is 5m. For longer distances, please use shielded twisted pair and consult our technical team.
Two methods: 1) Via display menu “System parameters” -> “Factory reset”, select “Yes”; 2) Write 0xFFFF to communication address 0x2B (43). After reset, all protection settings and communication parameters will be restored to default; reconfiguration is required.
ARD2F supports mapping up to 120 non-consecutive register addresses to consecutive custom addresses (5000~5119). Write the target address into 5300~5419, then quickly read via 5000~5119. Greatly improves polling efficiency.
ARD2F is positioned as a cost-effective, basic intelligent protector for conventional motor protection, measurement and control; ARD3M is positioned as an advanced digital terminal with additional features such as harmonic analysis, USB waveform export, Ethernet communication, and color display. Users can choose flexibly based on site requirements and budget.
