Bender IRDH275B-435 Insulation Monitor – Continuous insulation monitoring for IT (unearthed) power systems

The Bender IRDH275B-435 is an ISOMETER designed to continuously monitor insulation resistance in unearthed AC, DC, and mixed AC/DC IT systems. From my experience, it’s a solid choice when you need early warning of insulation degradation without shutting down the process. One thing I appreciate is the stable measuring behavior in noisy industrial environments and the straightforward alarm concept—simple to wire, simple to understand.

Company’s Order Placement Process and Guarantees

• Warranty period: 365 days
• Delivery: 1 week for in-stock; no more than one month at the latest
• Payment: 50% advance payment, full payment for delivery
• Express options: FedEx, UPS, DHL

Key Features

• Continuous insulation monitoring (IT systems) – Detects insulation drop before it becomes a ground fault, helping avoid unexpected shutdown.
• AC/DC and mixed systems – Monitors variable-speed drive systems, rectifiers, battery DC buses, and modern mixed networks reliably.
• Two-step alarming (prewarning/alarm) – Adjustable response values with two relay outputs for staged maintenance actions.
• Robust measurement principle – Bender’s AMP-style measuring method typically provides stable readings even with system leakage capacitance.
• BMS (RS‑485) connectivity – Integrates with Bender’s BMS network and supports connection to insulation fault location systems (EDS) in many cases.
• Self-monitoring and test/reset – On-device TEST/RESET functions and watchdogs improve diagnostic confidence.
• Front-panel mounting – 96 × 96 mm format makes retrofits straightforward on standard control panel doors.

Technical Specifications

Application Fields

You might notice that the IRDH275B-435 fits best where uptime matters and selective fault location is desired:

• Drives and automation panels in process plants (VFD-heavy AC networks)
• Battery-backed DC buses, energy storage, and UPS-backed IT systems
• Mining, marine, and rail applications using unearthed supplies
• Power conversion skids, rectifiers, and PV inverters operating as IT networks
• Laboratory and test benches where isolation monitoring is mandatory

Advantages & Value

• Reliability – Stable measurement under system leakage capacitance and harmonic noise; fewer nuisance trips.
• Compatibility – Works across AC/DC/mixed IT networks; integrates with Bender BMS and EDS for scalable fault location.
• Cost savings – Early detection reduces downtime and helps plan maintenance when it’s least disruptive.
• Drop-in retrofit – The 96 × 96 mm window is common; typically minimal panel rework.
• Technical support – From parameter suggestions to bus integration tips, we can help speed up commissioning.

Installation & Maintenance

• Panel and environment – Mount on a flat, ventilated control panel door; observe IP requirements; avoid condensation and vibration where possible.
• Wiring – Connect measuring leads to the IT system conductors and PE as per Bender’s terminal diagram. Keep signal wiring short and separated from high-frequency drive cables.
• System voltage – For higher nominal voltages, use the appropriate Bender AGH coupling device; this is a common oversight in upgrades.
• Alarms – Set prewarning and alarm thresholds based on your insulation baseline; many sites start with a conservative prewarning to trend behavior first.
• Routine checks – Run periodic TEST; verify relay actions; clean the front panel to keep the display/indicators readable. Firmware updates may be applicable in some variants—schedule during planned downtime.
• Safety – De-energize circuits before terminal work. Follow lockout/tagout and local electrical codes.

Quality & Certifications

• CE marked; RoHS compliant; manufacturer operates under ISO 9001 quality management
• UL/cUL compliance is typically available for this family; specific file numbers vary by variant
• Manufacturer’s standard warranty policy applies; our supply warranty is 365 days as stated above

A quick note from a customer in a compressor plant: “After swapping to IRDH275, nuisance alarms disappeared and we finally caught a cable nick before it took down the line.” That seems to be the typical benefit—better signal, fewer surprises.