Key Technical Specifications
| Parameter | Specification |
|---|---|
| Module | 3500/33 16-Channel Relay Module |
| Front Panel PN | 149986-01 |
| Rear I/O Module | Typically 149992-01 for 3500/33-01-00 |
| Relay Type | SPDT, epoxy sealed |
| Channels | 16 independent relay outputs |
| Max Switching Voltage | Up to 250 Vac (verify per certification option) |
| Arc Suppressor | 250 Vrms standard |
| Relay Contact Life | 10,000 to 100,000 cycles depending on load; verify OEM datasheet |
| Operating Mode | Normally De-energized or Normally Energized, selectable per group of 4 |
| Typical Power | 5.8 W |
| Diagnostics | OK LED, TX/RX LED, per-channel CH Alarm LED |
| Software | Requires 3500 Rack Config ≥ 3.3; Data Acquisition ≥ 2.40; Data Display ≥ 1.40 |
| Mounting | One full-height front slot + matching rear I/O slot |
| Dimensions (H×W×D) | Approx. 241 mm × 24.4 mm × 242 mm with rear module |
| Operating Temp | −30 °C to +65 °C |
| Safety Notes | Voltage derating applies for CSA -01 and SIL systems; higher voltages not allowed in SIL applications |
Product Introduction
The Bently Nevada 3500/33 149986-01 is a 16-channel relay module for the 3500 machinery protection rack. It converts alarm and trip conditions from monitoring modules into hard-wired relay outputs for shutdown systems, annunciators, and DCS interfaces.Each of the 16 SPDT relays can be programmed with AND/OR voting logic using any monitored channel in the rack. Relays are grouped in sets of four for Normally De-energized or Normally Energized operation. The module is not a monitoring channel itself — it reacts to alarms generated by 3500/40M, 3500/42M, 3500/45, 3500/53, and other monitor modules. For SIL-rated trips, voltage limits are restricted and must be confirmed against the current OEM certificate.
Installation & Configuration Guide
Preparation (10 min)
- Photograph the existing module: front label, rear I/O module, slot position, and DIP/switch settings.
- Confirm the rear I/O module matches — 149986-01 alone is not a complete assembly.
- Export or print the current 3500 Rack Configuration before any change.
- Verify relay load voltage does not exceed the certified limit for your approval option.
Removal (5–10 min)
- Confirm the rack is powered only if hot-swap is permitted by your site procedure.
- Label all rear terminal wires by channel number.
- Remove the front retaining screws, then withdraw the module.
- Inspect rear connector pins for bent contacts or carbon tracking.
Installation (10 min)
- Insert the replacement into the same slot position.
- Seat the rear I/O module fully before tightening front screws.
- Reconnect relay wiring exactly per the saved labels.
- Verify the ND/NE switch banks match the original configuration.
Power-On & Test (10 min)
- Confirm the OK LED is steady green.
- Check TX/RX LEDs flash during rack communication.
- Force each relay channel from the configuration software and measure contact closure.
- Verify trip logic against the saved configuration printout.
- Document firmware version and switch positions for the maintenance record.
Troubleshooting Quick Reference
| Symptom | Most Likely Cause | Fast Check |
|---|---|---|
| OK LED off | No power or module fault | Reseat module; check rack backplane |
| TX/RX LED not flashing | Backplane communication lost | Verify adjacent modules; reseat |
| Relay does not trip | Logic not assigned or forced | Check channel assignment in Rack Config |
| Relay trips unexpectedly | Wrong ND/NE switch setting | Compare switch bank to original photo |
| Contact voltage too high | Certification limit exceeded | Verify CSA/SIL derating on nameplate |
| CH Alarm LED stuck | Monitor channel in alarm | Check source monitor, not the relay |
| Intermittent output | Loose rear terminal | Torque terminals; inspect for arcing |
Dimensions, Mounting & Wiring Notes
- Mounting: One full-height front slot plus matching rear I/O slot in a 3500/05 rack.
- Dimensions: Approximately 241 mm × 24.4 mm × 242 mm with rear module installed.
- Relay Outputs: 16 × SPDT, grouped in four channels per ND/NE switch bank.
- Wiring: Relay terminals are on the rear I/O module. Keep trip wiring separate from analog signal wiring.
- Arc Suppression: 250 Vrms suppressors are standard; verify suitability for DC loads.
- ESD: Handle as a static-sensitive assembly. Use a grounded wrist strap.
FAQ
Is 149986-01 the complete relay module?
No. 149986-01 is the front panel assembly. The 3500/33 also requires a rear I/O module, commonly 149992-01 for the 3500/33-01-00 configuration. Order and verify both.Can I use it in a SIL-rated trip circuit?
Only if the certification option and voltage limits match your safety case. SIL applications restrict relay voltage — do not assume 250 Vac is permitted. Verify with the current Baker Hughes functional safety certificate.What is the difference between 3500/32 and 3500/33?
The 3500/32 provides 4 relay channels. The 3500/33 provides 16. They are not slot-equivalent and require different rear I/O modules.I replaced the module and the relays won’t trip. What should I check first?
Download the existing configuration and confirm each relay channel is assigned to a valid alarm source. Then verify the ND/NE switch banks match the original module.Does it support hot swap?
Yes, 3500 modules support hot-swap replacement under normal rack operation. Follow site safety procedures and confirm redundancy before removing any module.What software version do I need?
Minimum 3500 Rack Configuration 3.3, Data Acquisition 2.40, and Data Display 1.40. Newer revisions are recommended if available.Can you test it before shipping?
Function can be verified under test conditions: power-up, OK/TX-RX LEDs, relay actuation per channel, and switch-bank position. A full trip test requires access to the original rack configuration.
