990-05-50-02-00 | Bently Nevada | 990 Vibration Transmitter

Description

This two-wire, loop-powered device is designed to interface with a non-contacting 3300 NSv proximity probe and its matching extension cable. The 990-05-50-02-00 conditions the incoming proximity sensor signal into appropriate peak-to-peak vibration amplitude engineering units, converting it into a proportional 4 to 20 mA industry-standard current loop output. This analog output is transmitted directly to a machinery control system, such as a PLC or DCS, where standard protection alarming and machinery logic are performed.

The unit integrates the functionality of a Proximitor Sensor directly into its housing, requiring no separate external driver. It features a non-isolated PROX OUT coaxial connector and terminal block connection to supply a dynamic vibration and gap voltage signal for troubleshooting and machinery diagnostic operations. Built with potted construction, the device provides robust environmental protection suitable for highly humid or condensing locations.

Features

• Integrated Proximitor Sensor: Combines full proximity probe driver capabilities inside the transmitter housing to eliminate external signal conditioning modules.
• Standard 4 to 20 mA Output: Transmits a continuous analog current loop proportional to peak-to-peak vibration amplitude over a standard two-wire configuration.
• Dynamic Signal Diagnostic Interfaces: Provides non-isolated PROX OUT and COM terminals plus an integrated coaxial connector for direct connection to diagnostic tools.
• Integrated Not OK / Signal Defeat Circuit: Drops the loop current output to less than 3.6 mA within 100 microseconds of a probe or cable fault to prevent false control system alarms.
• Non-Interacting Field Adjustments: Accessible zero and span potentiometers underneath the device label facilitate straightforward field loop adjustments.
• Dedicated Test Input Pin: Allows for rapid on-site verification of the loop output current by using an external function generator as the input signal.
• Potted Enclosure Construction: Fully sealed housing protects internal electronic components against up to 100% condensing humidity conditions.

Applications

• Centrifugal air compressors
• Small industrial pumps
• Electric motor machinery monitoring
• Cooling and ventilation fans
• OEM machinery control system integration
• Overall vibration trending and peak-to-peak amplitude data acquisition

Ordering Information

Technical Specifications

Specifications apply at +22 Celsius (+72 Fahrenheit) using a 3300 NSv Probe and Extension Cable, and an AISI 4140 steel target unless specified otherwise.

Connections/Interfaces

Installation Guidelines

• Cable Specifications: Use 1.0 mm2 (18 AWG), 2-conductor, twisted, shielded cable for the 4 to 20 mA current loop and field terminal connections. The maximum loop cable run distance is 13 km (8 miles).
• Power Supply Voltage: Maintain a minimum voltage of +17 Vdc at the transmitter terminal when accounting for full loop resistance to prevent clipping at the 20 mA limit.
• Probe Gap Adjustment: Ensure the matched 3300 NSv proximity probe is gapped between 0.5 mm and 1.75 mm (20 and 55 mils) from the target surface during installation to ensure valid full-scale operations.
• Diagnostic Instrument Isolation: The PROX OUT signal is not electrically isolated from the 4 to 20 mA loop. Do not connect grounded, AC-powered test equipment directly to the BNC or terminal strips as it will cause loop interference or false trips. Connect via a 122115-01 Test Adapter to safely isolate and invert the signal.
• Bulkhead Mounting Alignment: Mount the transmitter base securely to a flat surface using the four integrated bulkhead mounting holes and the supplied 6-32 x 1.326 screws.
• Moisture Protection: Install connector protector sleeves over all ClickLoc coaxial junctions to maintain sealing integrity in environments subject to high humidity or condensation.

Compliance and Certifications

• FCC: Complies with Part 15 of the FCC Rules.
• EMC Standards: EN 61000-6-2, EN 61000-6-4, and EMC Directive 2014/30/EU.
• ATEX / IECEx: ATEX Directive 2014/34/EU; Ex ia IIC T4 Ga, and Ex ec IIC T4 Gc (Ta = -30 Celsius to +85 Celsius).
• RoHS: RoHS Directive 2011/65/EU and China RoHS with a 15-year EFUP designation under SJ/T 11364-2024.
• Maritime: ABS 2009 Steel Vessels Rules.
• North American Approvals: cNRTLus Class I, Division 2, Groups A, B, C, D (T5 @ Ta = +85 Celsius, Type 4 Enclosure).

FAQ

What is the behavior of the output loop current when a proximity probe is damaged or disconnected?

The transmitter is equipped with an internal Not OK and Signal Defeat circuit. If a faulty probe or open connection is experienced, the loop output current automatically drops to less than 3.6 mA within 100 microseconds to suppress false machine alarms in the control system.

Can I run standard plant diagnostic software using the 4 to 20 mA output of this transmitter?

The 4 to 20 mA signal provides overall peak-to-peak trending data only and is not compatible with plant-wide dynamic diagnostic systems like System 1. The analog output cannot determine the phase of vibration or handle specialized parameters like gap alarms or Trip Multiply.

Why is an external test adapter required when connecting an oscilloscope to the PROX OUT terminal?

The PROX OUT signal shares a common ground reference with the non-isolated 4 to 20 mA loop current. Connecting grounded, AC-powered diagnostic tools directly to the transmitter can alter the loop current and cause accidental machinery shutdowns, so an isolating test adapter must be used