Bently Nevada 990-04-50-02-01 Vibration Transmitter

Bently Nevada 990-04-50-02-01 990 Vibration Transmitter

Product Introduction

The Bently Nevada 990-04-50-02-01 belongs to the trusted 990 Vibration Transmitter series. This device continuously monitors shaft vibration on rotating machinery. It works with a non-contacting 3300 NSv Proximity Probe and extension cable. The transmitter converts probe signals into a standard 4-20 mA loop current. Facilities worldwide use this model for reliable protection against excessive vibration. Its compact design and hazardous area approval make it a versatile choice.

Technical Specifications of the 990 Vibration Transmitter

Measurement Range and Accuracy
This 990-04-50-02-01 covers a full-scale range of 0-4 mils pp (0-100 μm pp). Loop accuracy stays within ±1.5% over the specified full scale. This rating applies from the TEST input to a 250 Ω loop resistor. Note that the ±1.5% error adds to the Prox Out Incremental Scale Factor.

Power and Output
The unit requires +12 to +35 Vdc at the transmitter terminal. Maximum loop resistance reaches 1,000 Ω including cable at 35 Vdc. Typical current limiting is 23 mA. The output signal ranges from 4 to 20 mAdc in a 2-wire configuration.

Frequency Response and Probe Setup
Frequency response spans 5 Hz to 6,000 Hz (+0, 3 dB). The probe must be gapped between 0.5 and 1.75 mm (20 and 55 mils) from the target to achieve the full scale range. Minimum target diameter is 9.5 mm (0.375 in).

Not OK Condition Behavior
When a Not OK condition occurs, the signal output drops to less than 3.6 mA within 100 µs. After the fault clears, the output restores within 2-3 seconds.

Mechanical and Environmental Features

Mounting and Weight
The mounting option uses bulkhead screws. Transmitter weight is 0.43 kg (0.9 lbm). This lightweight housing simplifies panel or junction box installation.

System Length and Cabling
System length option is 5.0 metres (16.4 feet). For the Proximitor Sensor Output (BNC connector), the maximum cable distance is 3 metres (10 feet). Leadwire length should follow these limits to maintain signal integrity.

Approvals and Hazardous Area Use
This model carries CSA Division 2 approval. It suits NonHazardous, Zone 2 or Div 2 Hazardous area locations. The recommended power supply voltage is 28 V.

Installation and Setup Guide

Step 1 – Probe and Cable Connection
Connect one non-contacting 3300 NSv Proximity Probe and its extension cable to the transmitter. Ensure the total cable length does not exceed the specified maximum.

Step 2 – Power and Loop Wiring
Apply +12 to +35 Vdc at the transmitter terminals. Use a 2-wire configuration for the 4-20 mA loop. Keep loop resistance below 1,000 Ω at 35 Vdc.

Step 3 – Probe Gap Adjustment
Adjust the probe gap between 0.5 and 1.75 mm (20–55 mils) from the target surface. Use the non-interacting external zero and span adjustments to calibrate.

Step 4 – Testing and Verification
Inject a TEST signal and measure voltage across a 250 Ω resistor. Verify that the output stays within ±1.5% of the expected value.

Packaging List

• 1 x Bently Nevada 990-04-50-02-01 Vibration Transmitter

• 1 x Mounting hardware (bulkhead screws)

• 1 x Product quick reference card

Note: Cables, probes, and extension cables are sold separately.

Shipping and Delivery

We ship worldwide using FedEx, UPS, or DHL. All orders include tracking and standard insurance. Express shipping options are available upon request.

Frequently Asked Questions (FAQ)

1. What is the full-scale range of the 990-04-50-02-01?
The full-scale range is 0-4 mils pp (0-100 μm pp). This matches many medium-speed machines like fans and gearboxes.

2. Can I use this transmitter with a longer extension cable?
No. The maximum leadwire length for the Proximitor Sensor Output (BNC) is 3 metres (10 feet). Exceeding this may degrade signal quality.

3. How fast does the output drop during a fault?
The Bently Nevada 990 Vibration Transmitter pulls the output below 3.6 mA within 100 µs after a Not OK condition. This fast response helps safety systems act quickly.

4. What power supply voltage do you recommend for this model?
A 28 Vdc supply works well for most installations. However, the transmitter accepts +12 to +35 Vdc at the terminals.

5. Do I need a separate proximity probe to use this unit?
Yes. The 990-04-50-02-01 requires one 3300 NSv Proximity Probe and an extension cable. These are not included in the transmitter package.