Acrel ARD3T Automatic Motor Relay Protection Device

ARD3T automatic motor relay protection device can be divided into 7 modules including main module, measurement module, switch module, analog module, temperature module, communication module and liquid crystal module. It is small in size and compact in structure, and is suitable for motors with rated voltage up to AC660V, rated current up to AC800A, and rated frequency 50/60Hz. It can be directly installed and used in low-voltage control terminal cabinets and various drawer cabinets of 1/4 module or above, which improves the reliability and automation level of the control circuit.

automatic thermal protection motor
automatic thermal protection motor

Specifications of ARD3T automatic Motor Relay Protection Device


Technical parameters

Technical indicators

Protector auxiliary power supply

AC/DC110/220V or AC380V, power consumption 15VA

The rated working voltage of the motor

AC380V / 660V, 50Hz / 60Hz

Rated operating current of the motor

1 (0.1A-5000A)

Adopt measurement module

5 (0.1A-5000A)




Adopt outlay current transformer and measurement module



50mA-1A or 3A-30A

Adopt measurement module and leakage current transformer

Relay output contact capacity

Impedance load

AC250V, 6A; DC24V, 6A

Master switching input and output


Switching value module


Temperature module

Type of external sensor: PT100, PT1000, Cu50, PTC, NTC
Channel of the sensor: 3 channels
Sensor's corresponding measurement range: 

PT100/PT1000: -50°C~+500°C 

Cu50: -50°C~+150°C 

PTC/NTC: 100Ω~30kΩ

Analog module

2-channel 4-20mA input and 2-channel 4-20mA output

Master communication

RS485 Modbus_RTU

Communication module

double RS485 Modbus_RTU, Profibus_DP


Working temperature


Storage temperature


Relative humidity

≤95﹪No condensation, no corrosive gas



Pollution levels

Class 3

Protection grade

Main body IP20, split display module IP45 (installed on the cabinet panel)

Installation category

Level III

Features of ARD3T Automatic Motor Relay Protection Device


The module is small in size and supports rail installation and screw installation;


The additional modules are powered by the bus and do not need an external auxiliary power supply;


With upper computer configuration software, it is convenient for customers to configure parameters and program settings;


Two channels of 4-20mA input measurement and two channels of 4-20mA transmission output can be realized by adding analog modules. The corresponding parameters of 4~20mA transmission output can be set freely;


It can realize 3-way temperature measurement protection by adding a temperature module. The types of external sensors that can be connected are: PT100, PT1000, Cu50, PTC, NTC;


Profibus-Dp communication can be realized by adding Profibus module.

Diagram of ARD3T Automatic Motor Relay Protection Device

Diagram of ARD3T Automatic Motor Relay Protection Device
Diagram of ARD3T Automatic Motor Relay Protection Device
Typical Connection
Diagram of ARD3T Automatic Motor Relay Protection Device
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Related ARD Series Motor Protection Circuit Relay
+8618795636361 michelle.zhou@email.acrel.cn
No. 9 Xincheng Road, Chengjiang Street, Jiangyin City, Jiangsu Province, China.