Bently Nevada 3500/42 (350042-01-00) Proximitor/Seismic Monitor – 4‑Channel Vibration Protection for Critical Machinery

The Bently Nevada 3500/42 Proximitor/Seismic Monitor is a four-channel rack module designed for the 3500 machinery protection system. It measures and protects against shaft vibration, casing vibration, and position using proximity probes and seismic sensors—exactly the signals you need on turbines, compressors, pumps, and large fans. The ordering code 3500/42-01-00 (also written as 350042-01-00) identifies a common configuration used in many 3500 racks in the field. From my experience, it’s the workhorse module you select when you want both proximity and seismic coverage in one card, with buffered outputs for diagnostics and tight trip logic for protection.

Company’s Order Placement Process and Guarantees

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

Key Features

• Four independent channels – Each channel configurable for proximity or seismic measurement, which typically simplifies spares and cabinet layout.
• Proximitor and seismic compatibility – Works with eddy-current proximity probes (e.g., 3300 XL series) as well as velocity and acceleration sensors used on casing vibration.
• Buffered transducer outputs – Rear I/O provides buffered BNC access for portable data collectors and diagnostics without disturbing protection.
• Protection-grade alarms and trips – Dual setpoints per channel with OK/status, enabling shutdown logic through the rack’s relay modules.
• Keyphasor tracking support – When paired with a 3500/25 Keyphasor module, you can enable 1X amplitude/phase and other speed-referenced measurements.
• Rack-integrated communications – Data is exposed to plant systems via the 3500 system communications module (typically Modbus), not through the 3500/42 front card itself.
• Front card + rear I/O architecture – Clean wiring on the rear terminal base; quick front-card swap for maintenance without disturbing field cables.

Technical Specifications

Application Fields

This module is widely used in oil & gas, petrochemical, power generation, steel, pulp & paper, and water utilities. Typical machines include steam and gas turbines, centrifugal compressors, reciprocating compressors (for frame vibration), large pumps, ID/FD fans, blowers, and gearboxes. One thing I appreciate is how it combines shaft (proximity) and casing (seismic) coverage in the same card, so mixed trains—like a turbine driving a compressor—can be handled neatly in a single rack bay.

Advantages & Value

• Reliability – Designed for protection duty with robust OK/status handling and proven alarm logic in most installations.
• Compatibility – Works with common Bently Nevada probes and sensors; easy pairing with 3500/25 Keyphasor and 3500/33 Relay modules.
• Lifecycle cost – Buffered outputs simplify diagnostics; fewer site visits and quicker troubleshooting typically reduce downtime costs.
• System integration – Data presentation through the rack communications module makes DCS/PLC connectivity straightforward via Modbus.
• Spares strategy – Standard full-height format and common I/O reduce spare parts complexity across multiple machines.

A maintenance lead at a gas plant told us the move to the 3500/42 helped them standardize on one monitor for both probe and seismic points—fewer part numbers on the shelf and faster swaps during outages.

Installation & Maintenance

• Cabinet & rack – Install in a Bently Nevada 3500 rack mounted in a ventilated cabinet; keep ambient within the module’s operating range.
• Wiring – Use shielded cables for transducer runs; land all field wiring on the rear I/O terminal. Maintain proper probe gap and sensor polarity.
• Grounding – Bond shield drains at the rack end only, and ensure a clean instrument ground to minimize noise.
• Safety – Lock out/tag out any trip relay circuits attached to shutdown systems before working on the rack. Verify OK status before returning to service.
• Routine checks – Periodically verify probe bias/gap, review alarms/trips, and validate buffered outputs with a portable data collector.
• Firmware/config – When applicable, keep rack firmware and configuration files backed up; perform changes using approved procedures and management of change.

Common Supporting Components

• 3300 XL Proximitor Probe Sets – For shaft vibration, radial position, and thrust position measurements.
• 330500/330750 Seismic Velocity Sensors – For casing vibration points on motors, pumps, and fans.
• 3500/25 Keyphasor Module – Provides speed/phase reference enabling 1X tracking and vector measurements on the 3500/42.
• 3500/33 Relay Module – Adds voting and trip relay outputs for alarms/trips generated by the 3500/42.
• 3500 System Communications Module – Exposes measurements to DCS/PLC via Modbus (serial or TCP, depending on rack option).

Quality & Certifications

• CE compliant
• UL/cUL listed (typical for 3500 series racks and cards)
• RoHS compliant in many cases
• Manufacturer’s warranty terms apply; our supply warranty is 365 days as stated above

Notes: Specific options within 3500/42 ordering codes can vary. If you share your current rack configuration (probe types, Keyphasor presence, relay scheme), we can confirm exact compatibility and I/O module details before shipment.