Overview
The AIM-T300 is an insulation monitoring device designed for industrial IT power distribution systems (unearthed systems). It continuously monitors the insulation resistance to earth in real time. When the insulation level drops below a preset threshold, it issues an alarm signal, allowing maintenance personnel to identify and clear the fault promptly, thus preventing unplanned downtime and ensuring operational safety. Typical applications include mines, glassworks, chemical plants, explosion-hazard areas, computer centres, and emergency power supplies.
Highlight
Insulation Monitoring
- Range 1kΩ-5MΩ
- Response <6s (Ce=1μF)
Two-Stage Alarm Output
- Pre-alarm & alarm relays
- Adjustable 10kΩ-5MΩ
RS485 Communication
- Modbus-RTU protocol
- Connect to SCADA
Wide Auxiliary Power
- AC85-265V wide range
- Power <8W
Function
| Insulation Monitoring | Continuously measures insulation resistance of unearthed AC/DC systems up to 480V. Range 1kΩ-5MΩ, response time <6s (with 1μF leakage capacitance). |
| Two–Stage Alarm Output | Two independent relay outputs (pre-alarm and main alarm) with adjustable thresholds (10kΩ-5MΩ). Dry contacts for external alarm devices. |
| RS485 Communication | Built-in RS485 interface with Modbus-RTU protocol. Enables integration with SCADA, PLC, or building management systems. |
| LCD Display & Self–Test | Intuitive LCD shows real-time insulation value and alarm status. Self-test function verifies measurement accuracy. |
Specification
| Parameter | Value |
| Model | AIM-T300 |
| Auxiliary Power | AC85～265V |
| Power Consumption | < 8 VA |
| Monitored System Voltage | AC 0～480V, DC 0～480V |
| Rated Frequency | 40～60 Hz |
| Insulation Measuring Range | 1 kΩ ～ 5 MΩ |
| Pre-alarm / Alarm Setpoint Range | 10 kΩ ～ 5 MΩ |
| Response Time (with Ce = 1 μF) | < 6 s |
| Permissible System Leakage Capacitance | < 150 μF |
| Internal Measuring Voltage | < 20 V |
| Internal Measuring Current | < 170 μA |
| Internal DC Resistance | ≥ 120 kΩ |
| Relay Outputs | 2 × change-over (pre-alarm, alarm) |
| Communication Interface | RS485, Modbus-RTU |
| Operating Temperature | –20 °C ～ +60 °C |
| Storage Temperature | –20 °C ～ +70 °C |
| Relative Humidity | 5 % ～ 95 % (non-condensing) |
| Altitude | ≤ 2500 m |
| Cut-out Dimensions | 88 × 88 mm |
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FAQ
Connect the monitored system to terminals L1 and L2 (any two phases for three-phase systems). For DC systems, connect L1 to the positive pole and L2 to the negative pole. Ensure functional earth (KE, PE) is connected to the local equipotential earth bar.
Yes. The pre-alarm and main alarm thresholds are independently adjustable via the front panel menu from 10 kΩ to 5 MΩ.
It supports Modbus-RTU over RS485. The default baud rate is 9600 bps (other rates can be configured).
Check if the alarm recovery mode is set to “manual”. Enter the menu and change it to “automatic” to enable self-reset after fault clearance.
No. The AIM-T300 is rated for system voltages up to 480V AC/DC. For higher voltages (up to 690V AC / 800V DC), please consider the AIM-T500 or AIM-T500L models.
Summary
The AIM-T300 is a compact and reliable insulation monitor for industrial unearthed power systems. It offers wide measuring range, adjustable two-stage alarms, and easy integration via RS485 Modbus. With its intuitive LCD display and simple DIN-rail or panel mounting, it is an ideal choice for ensuring power continuity and safety in critical industrial environments.
