Description
Bender IRDH275-435 | ISOMETER Insulation Monitor
Product Introduction
An insulation fault in an unearthed power system can remain latent until a second fault creates a more serious operational or safety issue. The Bender IRDH275-435 ISOMETER is designed to monitor insulation resistance continuously and signal when the measured value falls below configured response thresholds.
The IRDH275-435 supports unearthed AC systems up to 793 V and DC systems up to 650 V. Its standard configuration includes two adjustable alarm thresholds, a 0–400 μA analog output, and an auxiliary supply compatible with 88–264 VAC or 77–286 VDC. With OEM article number B91065100, it is a specific replacement candidate for installations requiring this exact variant. Verify the installed device’s full model and wiring before ordering.
IRDH275-435
Key Technical Specifications
- Manufacturer: Bender
- Model: IRDH275-435
- Article Number: B91065100
- Product Series: ISOMETER IRDH275
- Device Function: Insulation resistance monitoring
- Monitored AC System Voltage: 0–793 VAC, 1-phase or 3-phase AC
- Monitored DC System Voltage: 0–650 VDC
- Auxiliary Supply (AC): 88–264 VAC
- Auxiliary Supply (DC): 77–286 VDC
- Auxiliary Supply Frequency: 42–460 Hz
- Power Consumption: ≤14 VA
- Response Value Range: 1 kΩ–10 MΩ
- Alarm Thresholds: Two independently adjustable response values
- Analog Output: 0–400 μA, proportional to measured insulation resistance
- Measuring Voltage: ±50 V peak
- Measuring Current: ≤278 μA at RF = 0 Ω
- Maximum System Leakage Capacitance: 500 μF
- Relay Outputs: Two SPDT changeover contacts
- Mounting: DIN rail or screw mounting
- Protection Rating: IP30 enclosure / IP20 terminals
- Operating Temperature: Verify against the applicable manual and unit revision
Specifications are based on Bender IRDH275 documentation for the standard -435 variant.
Global Sourcing & Live-Test SOP
For insulation-monitoring equipment, condition and functional performance must be established through controlled verification—not appearance alone.
Incoming Verification
- Confirm the complete -435 model marking.
- Verify OEM article number B91065100 where present.
- Photograph the front panel, nameplate, terminals, and housing.
- Inspect the display, keys, terminal blocks, and mounting features for damage.
Authenticity and Configuration Review
- Compare the nameplate against Bender documentation.
- Verify the auxiliary supply range before energizing.
- Confirm the monitored system type and voltage limits.
- Record response thresholds and relay operating mode, where accessible.
- Distinguish the standard from IRDH275B, W, or BW variants.
Functional Validation
- Power the device only with a verified compatible supply.
- Check startup, display operation, and built-in self-test.
- Test insulation response using an appropriate controlled test setup.
- Verify alarm relay operation and analog output.
- Record the test method, measured response, and results.
- Do not claim calibration or functional testing unless performed and documented.
ESD Protection and Shipment
- Protect the device from impact, moisture, and contamination.
- Secure terminal areas and mounting hardware.
- Use protective packaging suitable for electronic instrumentation.
- Include only accessories explicitly identified in the sale.
Field Engineer’s Pitfall Guide
- ❗ Do not confuse auxiliary supply with monitored system voltage. The -435 supply range is 88–264 VAC or 77–286 VDC. The monitored system range is a separate specification. Verify both before installation.
- ❗ Do not substitute an IRDH275B without checking the output requirements. The standard uses a 0–400 μA analog output, while IRDH275B versions provide selectable 0/4–20 mA outputs and additional features. Match the complete model to the control-system interface.
- ❗ Verify alarm thresholds and relay logic during commissioning. The device has configurable response values and relay behavior. Do not assume factory settings match the existing installation.
Intent-Driven FAQ
Q1: What is the Bender -435 used for?
It continuously monitors insulation resistance in unearthed AC and DC electrical systems and signals insulation faults.
Q2: What is the auxiliary supply vfor ?
The documented supply range is 88–264 VAC or 77–286 VDC. Confirm the nameplate before applying power.
Q3: What system voltage can it monitor?
The is rated for monitoring up to 793 VAC or 650 VDC without an external voltage coupler.
Q4the have an analog output?
Yes. Thard provides a 0–400 μA analog output proportional to the measured insulation resistance.
the interchangeable with IRDH275B-435?
Not automatically. The B variant has different features, including a different analog output configuration. Verify output requirements, article number, and system configuration before substitution.
Qthe be hot-swapped?
Do not assume hot-swap capability. Follow site electrical-safety procedures and Bender installation instructions.
Q7: What should I verify before buyinglus ?
Confirm the complete model, article number, auxiliary supply range, terminal condition, and documented functional-test status. Verify warranty and included accessories with the seller.
Procurement Note
The specifications above describe the documenteard , article B91065100. This listing does not assert that a particular surplus unit has been tested, calibrated, or supplied with a warranty. Confirm physical condition, included accessories, and test status before publishing.
