BENDER IRDH275-427 Insulation Monitoring Device | Replacement, Equivalent & Selection Guide
The BENDER IRDH275-427 is a high-performance insulation monitoring device (IMD) designed for ungrounded IT power systems. It continuously monitors insulation resistance between live conductors and earth, providing early fault detection to prevent unplanned shutdowns and electrical hazards. At Konmask.com, we supply genuine BENDER modules and verified compatible alternatives for industrial automation and critical power applications.
Technical Specifications
- Part Number: IRDH275-427
- Manufacturer: BENDER GmbH & Co. KG
- Series: IRDH275
- Function: Insulation Monitoring Device (IMD) for IT Systems
- Nominal System Voltage (Un): AC 0–690 V / DC 0–1000 V
- Measuring Voltage: DC ≤ 12 V
- Response Value (Ran): 1 kΩ – 10 MΩ (adjustable)
- Alarm Output: 2 relay outputs (fault + pre-warning)
- Communication Interface: RS-485 (BENDER BMS protocol)
- Supply Voltage (Us): AC/DC 24–240 V (wide-range)
- Degree of Protection: IP30 (front panel)
- Operating Temperature: −25 °C to +70 °C
- Mounting: DIN rail (35 mm) or panel mount
- Weight: approx. 1,560 g
- Standards: IEC 61557-8, IEC 60364-4-41, UL 508
- Approvals: CE, cULus
Compatible Replacement & Equivalent Models
When the IRDH275-427 is unavailable or a cost-optimized alternative is required, the following models offer comparable insulation monitoring functionality:
- BENDER IRDH275B-427 — Updated variant with enhanced BMS communication; direct drop-in replacement in most installations.
- BENDER ISOMETER® IR155-3204 — Compact IMD for EV/HV DC systems; suitable where DC-only monitoring is acceptable.
- BENDER IRDH375-427 — Higher-spec successor with extended voltage range and improved diagnostics; backward-compatible wiring.
- Littelfuse / SELCO E0550 — Third-party equivalent for AC IT systems up to 690 V; verify relay output compatibility before substitution.
- Schneider Electric IM400 — Alternative IMD for IEC 61557-8 compliant installations; requires adapter for BMS bus integration.
⚠ Always verify system voltage, response value range, and communication protocol before substituting. Contact [email protected] for a free compatibility check.
Why Choose the Original IRDH275-427
- ✅ Proven reliability — Widely deployed in hospitals, data centers, offshore platforms, and industrial plants worldwide.
- ✅ Adaptive measuring method — AMP technology eliminates interference from system capacitance, ensuring accurate readings in high-capacitance networks.
- ✅ Dual-channel alarm — Independent pre-warning and fault relays allow staged response without nuisance tripping.
- ✅ Wide supply voltage range — AC/DC 24–240 V eliminates the need for a separate power supply in most control cabinets.
- ✅ BMS bus integration — Native RS-485 support enables seamless integration with BENDER COM465 gateways and SCADA systems.
- ✅ Long service life — Designed for continuous 24/7 operation in harsh industrial environments.
Typical Applications
- Hospital operating theaters and ICU power systems (IEC 60364-7-710)
- Offshore oil & gas platforms and marine power distribution
- Industrial manufacturing lines with ungrounded IT networks
- Data center UPS and critical power infrastructure
- Railway traction and auxiliary power systems
- Renewable energy (solar/wind) DC bus monitoring
- Chemical and pharmaceutical process plants
System Compatibility
- BENDER BMS Bus: Compatible with COM465IP, COM465DP, and all BENDER BMS-capable devices.
- Coupling Devices: Works with BENDER AGH150W, AGH204W series coupling/separation modules.
- Locating Devices: Pairs with BENDER EDS series (EDS460, EDS490) for fault location in complex networks.
- PLC Integration: Relay outputs directly interface with Siemens S7, Allen-Bradley ControlLogix, and Mitsubishi MELSEC PLCs.
- SCADA/DCS: RS-485 Modbus RTU adapter available for integration with ABB, Honeywell, and Emerson DCS platforms.
Selection Guide
Use the table below to select the correct IRDH275 variant for your application:
- IRDH275-427 — AC/DC 24–240 V supply, RS-485 BMS, standard response range 1 kΩ–10 MΩ → General industrial IT systems
- IRDH275B-427 — Same as above + enhanced diagnostics display → Upgrade or new installations requiring local readout
- IRDH375-427 — Extended Un up to 1000 V AC, wider Ran range → High-voltage IT systems, renewable energy
- IR155-3204 — DC 0–1500 V, compact form factor → EV charging infrastructure, HV DC battery systems
Key selection parameters: System voltage (Un) · Supply voltage (Us) · Required response value (Ran) · Communication protocol · Mounting space · Certification requirements (UL/CE/ATEX)
Quality Assurance & Sourcing
- 🔒 Genuine parts — All BENDER products sourced through authorized distribution channels with full traceability.
- 🔒 Inspection — Each unit inspected for physical integrity, label authenticity, and packaging condition before dispatch.
- 🔒 Warranty — 12-month warranty against manufacturing defects; original BENDER warranty terms apply to new stock.
- 🔒 Documentation — Datasheet, CE declaration, and calibration certificate available upon request.
- 🔒 Anti-counterfeit — We do not source from grey-market channels; serial numbers verifiable with BENDER directly.
How to Order
- Confirm your system voltage (Un) and supply voltage (Us) requirements.
- Verify communication interface needed (standalone relay vs. BMS RS-485).
- Add BENDER IRDH275-427 to cart, or contact us for volume pricing.
- For urgent requirements, email [email protected] with your project specs for a same-day quote.
- International shipping available — DDP/DAP terms supported for most destinations.
Replacement & Compatibility FAQ
Q: Can the IRDH275B-427 directly replace the IRDH275-427?
A: Yes. The IRDH275B-427 is the updated variant and is electrically and mechanically compatible. Terminal assignments are identical.
Q: Is the IRDH275-427 suitable for DC IT systems?
A: Yes. It monitors both AC (0–690 V) and DC (0–1000 V) IT systems with the same unit.
Q: What is the difference between IRDH275-427 and IRDH275-4?
A: The “-427” suffix denotes the wide-range AC/DC 24–240 V supply voltage version. The “-4” suffix typically indicates a 24 V DC-only supply. Verify your control voltage before ordering.
Q: Can I use a Schneider IM400 as a replacement?
A: Functionally possible for basic insulation monitoring, but the IM400 does not support BENDER BMS RS-485 protocol. A Modbus RTU gateway would be required for bus integration.
Q: Do you supply IRDH275-427 with a test certificate?
A: Yes. Factory test certificates and CE declarations are available. Request at time of order.
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