Bently Nevada 3500/04-IS Ground Module – Single‑Point Earthing for 3500 Racks in I.S. Environments

The Bently Nevada 3500/04-IS is a dedicated ground module designed to establish a single, controlled earth reference for the 3500 machinery protection rack, especially where intrinsically safe (I.S.) inputs are used. From my experience, adding this module often reduces ground loops and helps quiet down random noise that can trigger nuisance alarms. It’s a simple, passive building block that typically makes a noticeable difference in electrically “busy” cabinets.

• Single-point earthing – Provides a defined, low-impedance reference point for the entire 3500 rack to help prevent ground loops.

• Intrinsic safety compatibility – The -IS variant is intended for racks using I.S. input channels/barriers, supporting proper bonding and segregation practices in hazardous areas.

• Noise mitigation – Shields and returns are referenced consistently, which in many cases reduces common-mode noise and spurious events.

• Passive design – No configuration, firmware, or field calibration; typically install and bond to plant earth and you’re done.

• Rack-integrated form factor – Fits the standard 3500 rack, keeping grounding and bonding inside the protection system rather than relying on ad-hoc cabinet terminals.

The 3500/04-IS is typically selected in plants that combine machinery protection with intrinsic safety—think Zone 1/Division 1 sensor loops feeding the 3500 rack. You might notice the benefits most in cabinets where multiple shielded cables converge and grounding discipline becomes critical.

• Oil & gas (compressors, turbines, and pumps in hazardous areas)

• Petrochemicals and refining (I.S. vibration and temperature loops)

• Pipelines and terminals (long cable runs with challenging EMC)

• Power generation (balance-of-plant skids using mixed I.S./non-I.S. signals)

• Reliability – A proper single-point ground seems to stabilize signal references and, in many cases, reduces nuisance alarms that eat into maintenance time.

• Compatibility – Designed for the 3500 ecosystem, including racks populated with intrinsically safe input options and barriers.

• Cost control – Fewer false trips and easier troubleshooting typically translate into avoided downtime and lower lifecycle cost.

• Simplicity – Passive hardware with no firmware, so there’s nothing to configure or update.

A maintenance lead at a gas processing site told us that after adding the ground module during a cabinet retrofit, they saw a noticeable drop in intermittent alarm chatter—no other changes, just better grounding discipline.

• Cabinet and rack – Install in a standard Bently Nevada 3500 rack within a clean, dry enclosure. Provide adequate ventilation consistent with the rack’s rating.

• Earthing practice – Bond the module to a low-impedance protective earth. Keep the earth conductor short, direct, and appropriately sized (many sites use ≥6 mm² for PE, subject to local code).

• Shield management – Terminate cable shields per plant standard; typically one-end shield grounding to the rack/ground module to avoid loops.

• Hazardous area – When used with I.S. channels, maintain separation and labeling for I.S. wiring. Only qualified personnel should install or modify these circuits.

• Routine checks – Periodically verify earth continuity, inspect terminations for corrosion/loosening, and confirm cabinet bonding integrity. No firmware or calibration is required for this module.

• CE-compliant; RoHS conformity typically available for the 3500 platform

• UL/CSA and hazardous area approvals (such as ATEX/IECEx) are available depending on system configuration and I.S. options

• Manufacturer’s warranty: standard Bently Nevada policy (commonly 1 year); extended coverage may be available via service agreements

If you’re specifying a mixed I.S./non‑I.S. 3500 rack, this module is a small line item that often saves time later. It helps keep the grounding strategy clean and predictable, which—in real plants—usually pays back quickly.