Bently Nevada 3500/33 (149986-01) – 16‑Channel Relay Module for Trip and Alarm Logic in 3500 Racks

The Bently Nevada 3500/33 is the 16‑channel relay workhorse for the 3500 machinery protection system. It listens to Alert, Danger, and Not OK conditions across the entire rack and converts them into clean, hardwired dry‑contact outputs for trips, interlocks, and annunciation. From my experience, this module is chosen when plants want rack‑level voting, latching, and time delay behavior without scattering extra interposing relays throughout the cabinet. Part number 149986-01 identifies a common hardware/I/O variant used in turbines, compressors, and critical pumps.

Key Features

• 16 independent dry-contact relays: Map any monitor channel’s Alert/Danger/Not OK to dedicated outputs for trips, ESD inputs, or alarms.
• Flexible logic: Voting (e.g., 2‑out‑of‑3), latching or non‑latching, time delays, and bypass—aligned to your site trip philosophy.
• Fail‑safe options: Normally Energized or Normally De‑energized to match safety practices and reduce spurious trips.
• Backplane integration: No transducer wiring to the module; it receives alarm status digitally over the 3500 rack backplane.
• Cleaner cabinets: Typically reduces interposing relay count and associated wiring, which tends to cut installation time and fault points.
• Traceable actions: Relay changes correlate with rack events and timestamps—useful during incident reviews.

Technical Specifications

Application Fields

You’ll typically find the 3500/33 wherever deterministic, hardwired trip paths are required:

• Gas and steam turbines: vibration, thrust position, or temperature Danger relays to turbine trip/ESD
• Compressors and expanders: interlocks to shutdown valves and anti‑surge systems
• Refining & petrochemicals: mapping critical alarms to DCS/PLC interlock matrices
• Balance‑of‑plant: fans, blowers, and critical pumps needing local alarms and permissive logic

Advantages & Value

• Reliability you can audit: Fail‑safe options and simple wiring reduce nuisance trips and make proof‑testing straightforward.
• Compatibility: Native to the 3500 ecosystem—no external logic solvers for many common trip schemes.
• Project savings: Fewer interposing relays, fewer terminals, and less engineering typically mean lower installed cost.
• Fleet standardization: Consistent hardware across units simplifies spares and reduces training overhead.

Installation & Maintenance

• Cabinet environment: Mount the 3500 rack in a clean, ventilated enclosure; avoid corrosive atmospheres and condensation.
• Wiring practices: Use the rear I/O terminal for dry contacts; keep wiring away from high‑noise power; for higher loads, drive an interposing relay.
• Logic setup: Configure voting, latching, and delays to mirror your site trip matrix; document proof‑test steps per relay.
• Safety & handling: De‑energize the rack before inserting/removing modules and follow ESD procedures to protect the backplane.
• Routine care: Function‑test relays during planned outages, back up configurations, and review event logs; firmware updates are best scheduled during turnarounds.

Quality & Certifications

• CE marking for EMC and safety (module family)
• UL/cUL and CSA certifications commonly available for 3500 system modules
• RoHS conformity where applicable
• Manufacturer warranty is typically 12 months; we support a 365‑day warranty on supply