Description
1. At-A-Glance Executive Brief
- Model: IRDH275B-435W (ISOMETER series)
- Brand: Bender
- Part Type: Insulation Monitoring Device (IMD) / Earth Fault Monitor
- Lifecycle Status: Mature / Legacy Support Platform
- System Compatibility: IT Systems (Ungrounded AC, DC, and AC/DC mixed networks)
- Core Protocol: Analog/Digital alarm relay outputs and communication interfaces
2. Technical Introduction
Unmonitored insulation degradation in ungrounded (IT) power distribution systems can escalate into catastrophic phase-to-ground faults or severe electrical shock hazards. The Bender IRDH275B-435W continuously surveys the insulation resistance of ungrounded AC, DC, or mixed AC/DC main circuits, injecting a measuring current to detect symmetrical and asymmetrical fault impedances. Deploying this monitoring unit into critical industrial power architectures ensures early fault detection and trip prevention without interrupting ongoing process operations.
3. Core Technical Specifications
| Parameter | Value |
| Nominal System Voltage (Un) | Up to AC 793 V / DC 650 V (dependent on coupling device settings) |
| Response Value (Ran) | Adjustable setting range (typically 1 k\Omega to 10 M\Omega) |
| Measuring Principle | Bender Automatic Adaptation Frequency Method |
| Supply Voltage (Us) | AC/DC 100…240 V / 48…400 Hz (Model variant dependent) |
| Outputs | Potential-free alarm relay contacts (Alarm 1 / Alarm 2) |
| Display / Interface | Front-panel LCD readout and setup configuration buttons |
| Mounting Type | DIN rail mounting or panel door installation enclosure |
| Operating Temperature | -10°C to +55°C (14°F to 131°F) |
4. Field Engineer’s Tech Notes
- Coupling Device Matching: Ensure the internal or external coupling transformer (such as an AGH series coupling unit) matches the maximum nominal voltage of your ungrounded network. Exceeding the rated voltage boundary of the coupling network will destroy the input measurement stage.
- Multiple IMDs on One Network: Never connect more than one active Bender ISOMETER to the same galvanically connected ungrounded system. Overlapping measuring signals will interfere with each other, causing erratic response values and false ground fault alarms.
5. Adaptive QA & Testing Protocol
Every pre-owned or New Surplus (NSFP) IRDH275B-435W unit undergoes rigorous hardware and functional verification on our dedicated electrical safety test bench before dispatch.
- Testing Actions: Technicians apply nominal control power and connect precision insulation resistance simulators to the input measurement terminals. We simulate graduated earth fault leaks ranging from healthy high-resistance states down to critical short-circuit thresholds, verifying that the internal microprocessor switches alarm relays and triggers LCD warning flags within required response times.
- Documentation: Comprehensive functional check reports and calibration validation logs are available upon request prior to shipment to ensure absolute out-of-box reliability.
6. Buyer’s FAQ
- What is the significance of the suffix code (-435W) on this model? The specific suffix designates factory-configured voltage ranges, response thresholds, and auxiliary power supply parameters tailored for industrial IT distribution networks. Cross-reference your exact nameplate string to ensure complete configuration parity.
- What warranty coverage comes with this insulation monitor? All units are backed by a comprehensive 12-month operational warranty covering electronic component integrity and measurement accuracy under load.
- How fast can an emergency replacement unit ship for unplanned plant outages? In-stock items ship same-day from our US facility via expedited global air freight to minimize downtime during critical electrical maintenance windows.
- Is calibration required upon installation? Units arrive pre-tested and factory-calibrated; however, technicians must program the specific response setpoints (Ran) via the front panel to match local plant safety coordination standards during commissioning.
