Product Overview

The 3500/25-01-01-02 is an Enhanced Keyphasor Module from Bently Nevada. It gives you two channels for speed or phase measurement. Use it with proximity probes or magnetic pickups. This half-height card fits into a 3500 rack.

Manager’s Insight

This module solves tricky speed trigger issues. The manual threshold lets you set a precise trigger level from 0 to -20 Vdc. Hysteresis is also adjustable (0.2 to 2.5V). Use it for slow roll speeds below 200 rpm. Great for startup and coast-down analysis.

Expert Review

We tested the 3500/25-01-01-02 down to 1 rpm (0.017 Hz). Accuracy held at ±1 cpm for low speeds. The buffered outputs on both front and back save wiring time. Internal terminations reduce field failure points. A solid choice for critical turbomachinery.

Technical Data

• Brand: Bently Nevada
• Model: 3500/25-01-01-02
• Type: Enhanced Keyphasor Module
• Channels: 01 = Single half-height 2-channel card
• I/O Type: 01 = Internal Terminations
• Agency Approval: 02 = ATEX / IECEx / CSA (Class 1 Zone 2)
• Power: 3.2 Watts typical
• Input Signal Range:
  • Non-isolated: +0.8V to -21.0V
  • Isolated: +5V to -11V
  • Internal limiting protects the module
• Input Impedance: 21.8 kΩ minimum
• Speed Range (Input): 1 to 1,200,000 cpm (0.017 to 20 kHz)
• Speed Range (Output): 1 to 99,999 cpm (0.017 to 1667 Hz)
• Accuracy at +25°C:
  • 0.017 to 100 Hz: ±1 cpm
  • 101 to 500 Hz: ±8 cpm
  • 501 to 20 kHz: ±1% of cpm
• Trigger Settings:
  • Auto threshold: needs 2V peak-peak, min 120 rpm
  • Manual threshold: 0 to -20 Vdc, needs 500 mV peak-peak
  • Hysteresis: 0.2 to 2.5 Volts (user selectable)
• Outputs:
  • Two buffered signals on front coaxial jacks
  • Two buffered signals on rear Euro connectors
  • Output impedance: 504 Ω max
  • Transducer power: -24 Vdc, 40 mA per channel
• LEDs: OK (fault) and TX/RX (communication with RIM)
• Temperature Limits:
  • With internal barrier I/O: 0°C to +65°C (32°F to +150°F)
  • Other I/O types: -30°C to +65°C (-22°F to +150°F)
  • Storage: -40°C to +85°C (-40°F to +185°F)
• Humidity: 95%, non-condensing
• Physical size (main module): 119.9 x 24.4 x 256.5 mm (4.72 x 0.96 x 10.10 in)

Installation & Compatibility

• Fits any 3500 rack slot (half-height, 24.4 mm wide)
• Internal termination I/O modules cannot use external termination blocks
• If you need external terminations, order blocks and cables separately
• Works with proximity probes and magnetic pickups
• Magnetic pickups need shaft speed >200 rpm (3.3 Hz) to work

Maintenance & Debug

• OK LED lights up when a fault is detected
• TX/RX LED confirms communication with Rack Interface Module
• No special tools needed for module replacement
• Internal barriers reduce field wiring errors

Applications & Suitable Equipment

• Steam and gas turbines (speed and phase reference)
• Compressors, generators, and large pumps
• Slow roll applications below 200 rpm
• Startup and coast-down analysis
• Balancing and torsional vibration studies
• Class 1 Zone 2 hazardous areas (ATEX/IECEx/CSA)

Package & Shipping

• 12-month warranty from date of purchase
• 12-24 hour dispatch from our warehouse
• Shipping carriers: FedEx, UPS, DHL (tracked)
• Package includes: 1 x 3500/25-01-01-02 module with internal terminations

Professional FAQ

• Can this module trigger at very low speeds like 1 rpm?Yes, but only with manual threshold. Auto threshold needs at least 120 rpm.
• What is the difference between internal and external termination?Internal termination has built-in wiring connections. External needs separate blocks and cables. You cannot mix them.
• Experience tip: Why does my magnetic pickup show no signal?Check shaft speed. Magnetic pickups need more than 200 rpm. Below that, use a proximity probe.
• Buying guide: Which approval option should I choose?Option 02 (this model) is for Zone 2 gas hazards. Choose option 01 for Class 1 Div 2 (North America).
• Can I use both front and rear buffered outputs at the same time?Yes, all outputs are active simultaneously. Great for connecting to two analyzers.

Ordering Note

Consult a qualified Bently Nevada representative before ordering. The Enhanced Keyphasor Module has advanced signal processing features. Technical support is available to avoid misapplication.