Description
Product Introduction
The Bently Nevada 3500/50-01-00 is a 2-channel, full-height speed processing and monitoring module designed for the 3500 Machinery Protection System. By converting voltage pulses from proximity probes, magnetic pickups, or optical transducers into precise RPM and acceleration readings, it acts as the primary tachometer and machinery speed conditioning card for rotating equipment.
Configured with the full-height main module option (-01) and standard unapproved agency rating (-00), the 3500/50 compares real-time shaft speed and acceleration against user-programmed alarm and Danger (trip) setpoints. It can be configured for four distinct monitoring modes: Speed Monitoring, Acceleration Monitoring, Zero Speed Detection, or Reverse Rotation Tracking—delivering critical protection logic to prevent catastrophic turbine overspeed events or gear train lockups.
Key Technical Specifications
| Parameter | Options / Configuration Value |
| Main Module Option (-01) | Full-Height 3500/50 Tachometer Front Module |
| Agency Approval Option (-00) | No Agency Approvals (Standard / Unclassified Area) |
| Input Channels | 2 Transducer Channels per Module (accepts Proximity or Magnetic Pickups) |
| Input Frequency Range | 0.01 Hz to 20 kHz (1 RPM to 120,000 RPM based on target events per revolution) |
| Transducer Input Range | +0.8 V to -21.0 V (Proximity) / +0.4 V to +120 V peak-to-peak (Magnetic Pickup) |
| Operational Modes | Speed Monitoring, Acceleration Monitoring, Zero Speed Detection, Reverse Rotation |
| Analog Outputs | Proportional 4–20 mA or 1–5 VDC outputs per channel (via rear I/O module) |
| Power Consumption | 5.8 Watts typical |
| Operating Temperature | -30°C to +65°C (-22°F to +150°F) |
Application Scenarios & The “Trench” Experience
Picture this: A steam turbine generator deck is undergoing full-load tripping tests. As steam valves trip open, the rotor accelerates rapidly toward its redline limits. The 3500/50 Tachometer card tracks shaft speed in real time across its dual channels. When acceleration rates spike past acceptable threshold ramps, the 3500/50 fires its trip logic down the rack backplane to the 3500/32 relay module within milliseconds, slamming steam trip valves shut before an overspeed catastrophic explosion can occur.
- Steam & Gas Turbine Drives – Overspeed & Acceleration Protection – Monitors rapid RPM acceleration ramps during load rejection events to trip steam/fuel valves.
- Hydroelectric Generators & Water Turbines – Zero Speed & Creep Detection – Tracks micro-RPM rotation (down to 1 RPM) to ensure the rotor has come to a dead stop before engaging mechanical braking jaws.
- Extruders & Gear Trains – Reverse Rotation Sensing – Uses dual staggered proximity probes to detect reverse shaft rotation, preventing mechanical damage to drive gears during shutdown back-pressures.
3500/50-01-00
3500/50-01-00
Transparency SOP: Quality Assurance & Testing
We test every 3500/50 module on dedicated 3500 rack test benches prior to shipment:
- Physical & Terminal Audit: Inspect faceplate locking levers, gold-plated edge connectors, and rear multi-pin header alignment.
- Backplane Power-On Diagnostics: Seat card in a 3500 test chassis, power up, and verify OK LED status during self-test routines.
- Frequency & Pulse Generator Injection Test: Inject calibrated variable-frequency pulse signals across both channels (0.01 Hz to 20 kHz); confirm exact RPM and acceleration readouts on Bently Nevada 3500 Rack Configuration Software.
- 4–20 mA Output Calibration Sweep: Connect a precision multimeter to rear I/O analog output terminals to verify output current accuracy at 0%, 50%, and 100% speed spans.
- Final QC & Anti-Static Packaging: Enclose module in ESD shielding bags and ship inside custom foam-lined cartons.
The Veteran’s Tech Trap Guide
- ⚠️ Not a Standalone Electronic Overspeed Shutdown System: While the 3500/50 provides high-speed overspeed alarm logic, it is designed for machinery monitoring and control interlocks. For SIL-rated electronic overspeed trip systems requiring API 670 compliance, specialized dedicated triple-modular redundant systems (like the Bently Nevada 3500/53 or Emergency Shutdown Systems) are required.
- ❗ Events Per Revolution (EPR) Setting: Accuracy depends entirely on matching the configuration setting in software to the actual number of teeth or notches on your shaft wheel (EPR). If your target gear has 60 teeth and you leave the card set to 1 EPR (single keyway notch), your reported RPM will be 60 times higher than actual speed!
- ⚠️ Proximity vs. Passive Magnetic Pickup Conditioning: If using passive magnetic pickups, remember that magnetic sensor voltage output drops off significantly at low shaft speeds. For Zero Speed detection (under 100 RPM), active proximity probes (like 3300 XL 8mm probes) MUST be used instead of magnetic pickups.
- ❗ Peak Acceleration Spike Thresholds: When configuring Acceleration Alarm setpoints, set time delays appropriately (0.1–1.0 seconds) to prevent false trips caused by momentary signal electrical noise during high-power breaker switching.
Frequently Asked Questions (FAQ)
Q: What do the option codes “-01-00” stand for in part number 3500/50-01-00?
A: -01 (Main Module) = Full-Height 3500/50 Tachometer Front Module; -00 (Approvals) = No Agency Approvals (Standard / Unclassified Area).
Q: Can a single 3500/50 module measure Reverse Rotation?
A: Yes. In Reverse Rotation mode, the 3500/50 uses both Channel 1 and Channel 2 connected to two physically offset proximity probes observing the same gear target to determine shaft rotation direction.
Q: Does the 3500/50 module supply power to field proximity probes?
A: Yes. The 3500/50 provides regulated -24 VDC transducer power to drive 3300 XL Proximitor sensors directly through its rear I/O module.
Q: Is the 3500/50 card hot-swappable?
A: Yes. You can remove or install a 3500/50 card while the 3500 rack is powered without interrupting primary machinery monitoring on adjacent cards (provided trip loops associated with that card have been bypassed).
Start Chat
