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Key Technical Specifications
| Parameter | Specification |
|---|---|
| Channels | 4 Independent Inputs |
| Input Signal | Proximity Probe (Eddy Current) |
| Probe Power | -24 V DC (supplied by module) |
| Frequency Range | 1 Hz to 20,000 Hz (60 to 1.2M CPM) |
| Voltage Range | -2 V to -22 V DC (typical operation) |
| Resolution | 12-bit ADC per channel |
| Trigger Level | Software configurable (-2 V to -20 V) |
| Output Signals | Keyphasor TTL pulses to backplane |
| Power Consumption | 3.5 Watts (typical) |
| Operating Temp | -30°C to +65°C (-22°F to +149°F) |
| Certification | CE, CSA, ATEX (Zone 2 pending config) |
| Slot Width | Single slot (35 mm) |
Product Introduction
The Bently Nevada 3500/25-01-01-00 serves as the primary interface for Keyphasor signals within the 3500 protection rack. It conditions raw eddy current probe data from turbomachinery shafts, generating precise once-per-revolution pulses required for vibration phase analysis and speed monitoring.This specific configuration (-01-01-00) includes internal termination and standard firmware optimized for general industrial turbines and compressors. Field data indicates this revision handles signal noise rejection effectively up to 15 kHz, outperforming older 7200 series cards in high-RPM applications. Units are tested against a simulated 10 kHz square wave to ensure trigger accuracy before shipment.
Installation & Configuration Guide
Installation & Configuration GuidePreparation (10 min)
- Verify rack power is OFF. Check the 3500 frame ground strap; a loose ground causes erratic Keyphasor counts.
- Confirm the target slot is empty and the backplane connector pins are not bent.
- Have a small flathead screwdriver ready for terminal block retention clips.
Removal (5–10 min)
- If replacing an existing card, note the DIP switch settings on the old unit first. (Take a photo. Seriously. You will forget the pattern once the card is out.)
- Unscrew the front panel mounting screws.
- Pull the card straight out using the ejector handles. Do not wiggle excessively; backplane pins can shear.
Installation (10 min)
- Inspect the new 3500/25 module for shipping damage. Check the green terminal block for cracked plastic.
- Slide the module into the designated slot until the backplane connector seats firmly.
- Secure the front panel screws to ensure proper EMI shielding.
- Wire the proximity probe cables to the terminal block: Terminal 1 (Signal), Terminal 2 (Common), Terminal 3 (Probe Power -24V). Tighten to 0.5 Nm.
Power-On & Test (10 min)
- Apply 24 V DC to the rack power supply. Measure voltage at the rack terminals; it must be 24.0 V ± 0.5 V.
- Observe the “OK” LED on the module. It should flash slowly (1 Hz) during boot, then stay solid green.
- If the LED turns amber, the module detected a configuration mismatch. Connect the 3500 Rack Configuration Software via the serial port to verify the .cdm file matches the hardware revision.
- Simulate a shaft rotation using a function generator (1 kHz sine wave) on Channel 1. Verify the “Inhibit” LED remains off and the software reads a valid frequency.
Troubleshooting Quick Reference
| Symptom | Probable Cause | Action |
|---|---|---|
| OK LED is Red | Internal hardware fault or watchdog timeout. | Reseat the card. If persistent, replace unit. Check rack backplane voltage. |
| OK LED is Amber | Configuration mismatch (Software vs. Hardware). | Reload the correct configuration file (.cdm) from the engineer’s laptop. |
| No Keyphasor Pulse | Probe gap incorrect or cable shorted. | Measure DC bias voltage at terminals. Should be -8 V to -10 V for standard probes. Adjust probe gap. |
| Erratic Frequency Reading | Electrical noise or grounding issue. | Check shield grounding. Ensure probe cable is not running parallel to VFD power lines. |
| Channel Inhibited | Signal amplitude below threshold. | Lower the trigger level in software or check probe sensitivity (mV/mil). |
Dimensions, Mounting & Wiring Notes
- Dimensions: 133.4 mm (H) × 25.4 mm (W) × 220 mm (D) (Standard 3500 form factor).
- Mounting: Slides into 3500 Series rack guide rails. Secured by two front-panel M4 screws.
- Terminal Notes: Uses removable green terminal blocks. Wire gauge: 14–22 AWG (0.2–0.5 mm²). Strip length: 7 mm.
- Warning: The -24 V DC probe power is internally fused. Do not short Terminal 1 to Terminal 3 during wiring, or the internal fuse will blow, requiring factory repair.
FAQ
Q: Will the 3500/25-01-01-00 work in a rack configured for the -02-00 version?
A: Physically, yes. Functionally, no. The -02 version often has different filter settings or alarm logic. You must update the rack configuration file to match the specific hardware revision of the -01-01-00, or the system will flag a “Hardware Mismatch” error and inhibit alarms.Q: I need this tomorrow for a turbine shutdown. Do you have stock?
A: We keep a rotating stock of tested surplus units. If ordered before 2 PM EST, we ship same-day via FedEx Priority. Call immediately to reserve a specific serial number range if your site requires strict traceability.Q: Can I use this module with non-Bently probes?
A: Technically, yes, if they are negative-voltage eddy current probes requiring -24 V excitation. However, the linear range and sensitivity must match the Bently Nevada standard (approx. 200 mV/mil). Using incompatible probes yields inaccurate gap voltages and false trips.Q: What does the “00” at the end of the model number mean?
A: It indicates the approval/certification level. “00” generally denotes standard CE/CSA certification without specific ATEX or IECEx hazardous location approvals built into the hardware label. For Zone 1 environments, verify your local safety regulations; you might need an external barrier.Q: My old card failed due to a lightning strike. Will this replacement survive?
A: This unit has the standard internal protection. If your site is prone to surges, we strongly recommend installing external signal conditioners or surge suppressors at the junction box. The 3500/25 is sensitive to common-mode voltage spikes greater than 50 V.Q: Is the firmware updatable by the user?
A: No. Firmware is flashed at the factory. If a newer revision is required for compatibility with a 3500/40M communications gateway, you must order a specific firmware revision code or send the unit to an authorized service center. Do not attempt to flash third-party binaries.
