Overview
The AIM-D100-T series DC insulation monitor is specifically designed for unearthed DC systems (IT systems) to ensure operational safety by continuously monitoring the insulation resistance of both positive and negative poles to earth. When the insulation resistance falls below preset thresholds, the device issues pre alarm or alarm signals. Based on the unbalanced bridge principle, it overcomes the limitation of balanced bridges that fail to detect faults when both poles are simultaneously grounded. Typical applications include DC switchgear in power plants and substations, EV charging infrastructures, UPS systems, photovoltaic DC systems, energy storage systems, and other DC networks.
Highlight
Wide DC Voltage Range
- DC 10-1000V (two models)
- TH: 100-1000V, TL: 10-100V
- Suitable for diverse DC systems
High Precision Insulation
- 1kΩ-10MΩ, accuracy ≤3%
- Response time: 500ms or 1000ms
- Unbalanced bridge design
Flexible Communication
- RS485 Modbus-RTU protocol
- Baud rate adjustable: 4800-38400bps
- Easy SCADA integration
Multiple Alarm Outputs
- 3 relay outputs, NO/NC selectable
- Independent pre-alarm & alarm thresholds
- Dry contacts, AC250V/DC30V 5A
Function
| Insulation Monitoring | Continuously measures insulation resistance of positive and negative poles to earth. Range: 1kΩ～10MΩ. Pre-alarm and alarm thresholds can be set independently. |
| Voltage Monitoring | Real-time measurement of system voltage (pole-to-pole) and pole-to-earth voltages. |
| Over/Under Voltage Alarm | Issues an alarm when system voltage exceeds 120% or drops below 80% of the rated voltage |
| Pre–alarm & Alarm | Two independent adjustable setpoints for pre-alarm and alarm |
| LED Indication | Panel LEDs indicate running, communication, fault, overvoltage, and undervoltage status |
| LCD Display | 128×32 dot-matrix LCD shows parameters and system information |
| Relay Output | Three relay outputs (NO/NC selectable) for remote signalling of insulation fault, pre-alarm, and voltage alarms |
| Event Recording | Up to 20 fault records with time stamp and fault type for easy troubleshooting |
| Communication | One RS485 interface with Modbus-RTU protocol for SCADA integration |
| Rail Mounting | Standard 35mm DIN rail mounting for easy installation |
| Plug–in Terminals | Plug-in terminal blocks simplify wiring and maintenance |
Specification
| Parameter | Value |
| Auxiliary Power | DC 12～36V |
| Max. Power Consumption | ≤6 W |
| Voltage Measurement Range | AIM-D100-TH: DC 100～1000V AIM-D100-TL: DC 10～100V |
| Voltage Accuracy | Class 0.5 |
| Overvoltage Threshold | ≥ 120% of rated voltage |
| Undervoltage Threshold | ≤ 80% of rated voltage |
| Insulation Resistance Range | 1 kΩ ～ 10 MΩ |
| Pre-alarm / Alarm Setting Range | 10 kΩ ～ 10 MΩ |
| Insulation Accuracy | 1～10 kΩ: ±1 kΩ 10～500 kΩ: ≤3% |
| Permissible System Leakage Capacitance | ≤5 μF |
| Insulation Monitoring Method | Periodic trigger (5～500 s adjustable) or communication trigger |
| Insuration Monitoring Time | 500 ms / 1000 ms per cycle |
| Internal DC Resistance | <1 MΩ |
| Alarm Outputs | 3 relay outputs, NO/NC selectable |
| Contact Rating | AC 250V 5A / DC 30V 5A |
| Fault Records | 20 |
| Communication Interface | RS485, Modbus-RTU |
| Mounting | 35 mm DIN rail |
| Protection Degree | IP30 |
| Operating Temperature | –20 °C ～ +60 °C |
| Storage Temperature | –25 °C ～ +75 °C |
| Relative Humidity | <95% (non-condensing) |
| Altitude | <2000 m |
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FAQ
The series includes two models: AIM-D100-TH for DC 100～1000V systems and AIM-D100-TL for DC 10～100V systems. Choose the model according to your system voltage.
It uses an unbalanced bridge measurement principle, which effectively detects insulation drop even when both poles are simultaneously grounded – a limitation of traditional balanced bridges.
Yes. Pre-alarm and alarm thresholds can be independently adjusted for both positive and negative poles, ranging from 10 kΩ to 10 MΩ.
The device can store up to 20 fault records, including fault type, measured value, and time stamp. The latest record is stored first.
The AIM-D100-T series supports Modbus-RTU over RS485, allowing easy integration with SCADA or building management systems.
Summary
The AIM-D100-T series DC insulation monitor is a compact, high-precision solution for ungrounded DC systems. With wide voltage coverage, accurate insulation measurement, flexible alarm settings, and Modbus communication, it provides reliable protection for critical DC power infrastructures. Its event logging and multiple relay outputs simplify troubleshooting and integration, making it an ideal choice for power plants, substations, renewable energy systems, and industrial DC networks.
