BENTLY NEVADA 3500/33-01-00 – 16?Channel Relay Module for Machinery Protection Outputs

The 3500/33-01-00 is Bently Nevada’s 16?channel relay module designed to translate monitor alarms into hardwired, fail-safe relay outputs for trips, shutdowns, and annunciation. It slots into a 3500 rack and pairs with a rear I/O module, giving you flexible, plant-ready dry contacts without external relay banks. You’ll typically see it used to consolidate alarm logic and drive ESD/PLC interlocks from vibration, temperature, and speed monitors in the same rack.

You might notice it’s sometimes called an “input” module in listings; functionally, this unit is an output relay module. From my experience, that clarity matters when you’re planning wiring and trip logic across a critical machine train.

• 16 Form C relay outputs – Dry-contact SPDT outputs for trips, permissives, annunciators, or PLC/ESD inputs.

• Configurable logic – Map any rack monitor alarms (e.g., 3500/42, /45, /60) with options for latching/non?latching, time delays, and voting (such as 2oo3).

• Fail-safe behavior – Normally?energized or de?energized configurations help meet plant safety philosophies.

• Integrated with the rack – Powered via the 3500 backplane; configuration and events handled through the 3500/22M TDI and configuration software.

• Front-panel status – Typical OK/BYPASS indicators aid quick diagnostics during commissioning and routine checks.

• One-slot footprint – Uses a single rack position with a matching rear I/O module for straightforward field wiring.

• Channel grouping – Assign individual or grouped relays to alarms/trips for flexible shutdown strategies.

This module is widely used wherever you need deterministic relay outputs tied to high?integrity monitoring:

• Oil & gas and petrochemical units – compressor trains, charge pumps, steam turbines, and expanders.

• Power generation – gas and steam turbines, generator auxiliaries, balance-of-plant equipment.

• Refining and pipelines – booster pumps, product pumps, and custody transfer support systems.

• Heavy industry – paper machines, large fans/blowers, critical gearboxes, and mill drives.

A maintenance lead at a Gulf Coast refinery told me they mapped three independent high?vibration alarms into 2oo3 voting on the 3500/33 to cut nuisance trips by half, while keeping shutdown integrity intact. That seems to be a common pattern for multi?bearing machines.

• Reliability – Industrial?grade relay design and fail?safe options align with plant trip philosophies.

• Compatibility – Works natively with all 3500 rack monitors; no external logic box needed in most cases.

• Cost & wiring efficiency – Reduces separate relay panels and simplifies terminations to DCS/PLC/ESD.

• Serviceability – Clear status indication, modular replacement, and configuration via familiar 3500 tools.

• Long lifecycle support – Stable platform with a large installed base and proven spares strategy.

• Cabinet/Rack – Mount in a standard 3500 rack within a well?ventilated enclosure. Keep ambient within the rack’s specified range and avoid direct heat sources.

• Wiring – Use the rear I/O terminals; segregate trip circuits from low?level signals. Clearly label common, NO, and NC contacts. Observe site standards for ESD/PLC input wiring.

• Grounding – Follow rack grounding practices to minimize interference and ensure safe fault clearing.

• Configuration – Set latching, time delays, and voting in the 3500 configuration software. Verify each relay with a functional test before placing the machine on risk.

• Routine checks – Periodically proof?test relays, confirm contact operation, and review event logs. Firmware and configuration should be managed via the 3500/22M TDI under MOC procedures.

• Conformity: CE and UL/cUL for the 3500 system; hazardous area approvals (e.g., ATEX/IECEx) available by specific option codes.

• Manufacturing: Built under ISO 9001 quality systems.

• Environmental: RoHS alignment on many variants; confirm per part number and site requirement.

• Warranty: Manufacturer’s standard warranty (commonly 1 year); extended coverage often available.

If you’re replacing legacy trip relays or standardizing across multiple racks, the 3500/33-01-00 typically gives a neat balance of channel density and configuration flexibility without complicating the shutdown architecture.