3500/70M

3500/70M Recip Impulse Velocity Monitor

The 3500/70M Recip Impulse Velocity Monitor is a 4-channel device used in reciprocating compressor systems to monitor crankcase and crosshead vibration. It takes input from seismic transducers, conditions the signals to derive vibration measurements, and compares them with user-programmable alarm setpoints.

The device supports the following functions, which can be programmed via the 3500 Rack Configuration Software:

• Impulse Acceleration
• Acceleration 2
• Recip Velocity
• Low Frequency Recip Velocity

Channel Programming

The monitor channels can be programmed in pairs, allowing up to two functions to be performed simultaneously:

• Channels 1 and 2 can perform one function.
• Channels 3 and 4 can perform the same or a different function.

Primary Purpose

The 3500/70M Recip Impulse Velocity Monitor provides:

• Machinery Protection: Continuously compares monitored parameters against configured alarm setpoints to trigger alarms.
• Essential Data: Provides valuable information for both operations and maintenance teams.

Each channel processes its input signal, generating static values, and you can configure alert and danger setpoints for the active static values.

Specifications

Inputs

• Signal Type: Accepts 1 to 4 proximity probe signals.
• Input Impedance:
  • Acceleration Input: 10 kΩ
  • Velocity Input: >1 MΩ
• Special Inhibit: Contact closure, 5 Vdc @ 390 μA (typical).

Power Consumption

• 7.7 watts (nominal).

Sensitivity

• Impulse Acceleration: 0.51 – 11.72 mV/(m/s²), 5 – 115 mV/g.
• Acceleration 2: 0.51 – 11.72 mV/(m/s²), 5 – 115 mV/g.
• Recip Velocity: 3.54 – 22.64 mV/(mm/s), 90 – 575 mV/(in/s).
• Low Frequency Recip Velocity: 3.54 – 22.64 mV/(mm/s), 90 – 575 mV/(in/s).

Outputs

• Front Panel LEDs:
  • OK LED: Indicates proper operation.
  • TX/RX LED: Indicates communication with other modules in the 3500 rack.
  • Bypass LED: Indicates when the monitor is in bypass mode.
• Transducer Power Supply:
  • Voltage: Minimum -22 Vdc.
  • Current: 40 mA maximum (15 mA on startup).
• Output Impedance:
  • Operating: 20 Ω typical.
  • Under Foldback Conditions: 1000 Ω typical.
• Protection: Foldback current between 15.4 and 24.9 mA.

Front Panel Buffered Outputs

• Buffered Transducer Outputs:
  • One coaxial connector per channel.
  • Output Impedance: 550 Ω typical.
  • Protection: Short-circuit protection for each connector.

Recorder Outputs

• Recorder Output: +4 to +20 mA, proportional to full-scale monitoring.
  • Selects one static data value per channel for use as the recorder value.
  • Voltage Compliance: +12 Vdc maximum.
  • Load Resistance: 600 Ω maximum.
  • Resolution: 0.3662 µA maximum.
  • Update Rate: Less than 100 milliseconds.
  • Accuracy: ±0.05 mA, ±0.14 mA over the temperature range.

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