Bently Nevada 990-04-70-01-01 Vibration Transmitter

Bently Nevada 990 Vibration Transmitter with CSA Division 2 Approval

Product Introduction

The 990-04-70-01-01 belongs to the Bently Nevada 990 series of vibration transmitters. This device converts radial vibration signals from a 3300 NSv proximity probe into a standard 4-20 mA current loop output. Specifically, it suits OEMs of centrifugal air compressors, small pumps, motors, and fans that need a proportional vibration signal for their control systems. Moreover, the transmitter integrates the Proximitor function internally, so no external signal conditioning module is required.

Key Technical Specifications

The 990-04-70-01-01 operates as a loop-powered device requiring +12 to +35 Vdc at the transmitter terminals. Its full-scale range is 0-4 mils pp (0-100 μm pp). Meanwhile, the 4-20 mA output accuracy stays within ±1.5% over the specified full-scale range.

The transmitter accepts input from one non-contacting 3300 NSv proximity probe and its matching extension cable. The system length option -70 denotes a 7.0-meter (23.0-foot) cable length. Furthermore, current limiting occurs at 23 mA typical, and the maximum loop resistance is 1,000 Ω including cable at 35 Vdc. Zero and span adjustments are non-interacting and accessible externally.

Additionally, the frequency response spans 5 Hz to 6,000 Hz +0, -3 dB, covering typical rotating machinery vibration bands. The minimum target size is 9.5 mm (0.375 in) diameter for reliable signal pickup.

Mechanical and Environmental Parameters

The mounting option -01 provides 35 mm DIN-rail clips, allowing quick snap-on installation inside machinery protection cabinets. The transmitter must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from target to ensure full-scale range coverage. Its compact housing suits dense panel layouts where space is limited. Weighing just 0.43 kg (0.9 lbm), the unit ships at minimal freight cost.

The agency approval option -01 provides CSA Division 2 certification for installation in hazardous classified areas. Therefore, users can deploy this transmitter in petrochemical and oil & gas environments where flammable vapors may be present. In such locations, the power supply must be limited to 28 V.

Installation Guide

First, verify that the DIN-rail section is clean and free of debris before mounting the transmitter. Next, clip the unit onto the 35 mm rail until the locking tab engages firmly. Connect the 3300 NSv probe and extension cable to the transmitter input. Then, wire the 4-20 mA loop observing correct polarity for the 2-wire configuration.

Set the probe gap between 0.5 and 1.75 mm using a feeler gauge or DC voltage method. Route the probe coaxial cable through grounded conduit to minimize electromagnetic interference. Finally, perform a loop check using the TEST input to verify output accuracy across the full-scale range.

Packaging List

• 1 × Bently Nevada 990-04-70-01-01 Vibration Transmitter

• 1 × DIN-rail mounting clip set

• 1 × Technical documentation folder

FAQ

Q1: What does the -70 suffix mean on this model?
A1: The -70 indicates a 7.0-meter (23.0-foot) system length between the probe and transmitter. Do not cut or extend this factory-tuned cable.

Q2: Can this transmitter work with probes other than the 3300 NSv?
A2: No. The 990-04-70-01-01 is calibrated specifically for Bently Nevada 3300 NSv proximity probes and matching extension cables.

Q3: What probe gap does this transmitter require?
A3: Gap the probe between 0.5 and 1.75 mm (20 and 55 mils) from the target. This range ensures full-scale output coverage.

Q4: What happens if the probe cable breaks during operation?
A4: The Not OK circuit drives the output below 3.6 mA within 100 µs, alerting the control system to a fault condition.

Q5: How do I verify the transmitter output without running the machine?
A5: Use the TEST input terminals to inject a simulation signal. The output should track proportionally across the 4-20 mA range within ±1.5% accuracy.