Bently Nevada 991-01-XX-01-00 MOD: 284318-01 Thrust Transmitter: Precision Axial Displacement Monitoring for Industrial Machinery

Product Description

The Bently Nevada 991-01-XX-01-00 MOD: 284318-01 is a highly specialized thrust transmitter, engineered to precisely measure axial displacement (thrust) in industrial machinery. It is particularly tailored for original equipment manufacturers (OEMs) of centrifugal air compressors, small pumps, motors, and fans. This transmitter plays a crucial role in providing a straightforward 4 – 20 mA proportional axial displacement signal, which serves as a vital input for machinery control systems.

As a 2 – wire, loop – powered device, it seamlessly integrates with the Bently Nevada 3300 nsv* proximity probe and its corresponding extension cable, available in system lengths of 5 m and 7 m. Once the input signal from the proximity probe is received, the 991 transmitter processes and conditions it. It converts the raw data into appropriate engineering units that are directly proportional to the shaft’s axial position. This processed information is then output as a 4 – 20 mA industry – standard signal. This output is fed into the machinery control system, where it is utilized for machinery protection alarming and logic operations.

Product Parameters

Parameter	Specification
Module Type	Thrust Transmitter
Input Signal Source	3300 nsv Proximity Probe
Output Signal	4 – 20 mA Proportional Axial Displacement Signal
Power Supply	+12 to +35 VDC (input at the transmitter terminal)
Accuracy	± 1.5% over the full – scale range (typical). Rated from the test signal input to the voltage measured across a 250 ω loop resistance
Maximum Loop Resistance	1,000 ω (including cable) at 35 VDC
Zero and Span Adjustment	Non – interacting external adjustments for fine – tuning
Proximitor Sensor Output	Compatible with ungrounded, portable test equipment. For grounded, ac – powered test equipment, use the 122115 – 01 test adapter for isolation
Output Impedance	10 k ω for a 10 m ω load
Linear Range	0.25 – 1.65 mm (10 – 65 mils) for Prox Out. Suitable for 0.6 – 0.6 mm or 25 – 0 – 25 mils current loop linear ranges
Temperature Stability	Incremental scale factor remains within ± 10% from 0 °C to + 70 °C (+ 32 °F to + 158 °F)

Product Specifications

Series

The 991-01-XX-01-00 MOD: 284318 – 01 is part of Bently Nevada’s range of high – quality industrial monitoring and control products. Bently Nevada has a long – standing reputation in the industry for providing reliable and accurate solutions for machinery protection and condition monitoring. Their product portfolio includes a wide variety of sensors, transmitters, and monitoring systems. The 991 thrust transmitter series, to which this model belongs, is designed with a focus on meeting the specific needs of OEMs and end – users in industries where precise measurement of axial displacement is critical for ensuring the smooth operation and longevity of machinery.

Features

Integrated Proximitor Sensor

Eliminates the need for an external unit, simplifying the overall installation process. This not only reduces the complexity of the system but also minimizes the potential for connection errors and failures associated with additional components.

Dynamic Signal Output

Equipped with non – isolated “Prox Out” and “Com” terminals, along with a coaxial connector, it provides a dynamic vibration and gap voltage signal output. This feature is invaluable for diagnostic purposes, allowing maintenance personnel to quickly assess the health of the machinery and identify any potential issues related to vibration or shaft – to – probe gap.

Test Input Pin

Facilitates quick verification of the loop signal output. By using a variable dc voltage source as the input, technicians can easily check if the transmitter is functioning correctly. This reduces the time required for troubleshooting and maintenance, improving overall system uptime.

Power – up Inhibit Circuit

Designed to eliminate signal errors that could be caused by line voltage transients. This ensures stable and reliable operation, even in environments where electrical power fluctuations are common.

Not OK / Signal Defeat Circuit

Prevents high outputs or false alarms that could occur due to a faulty proximity probe or loose connection. This is a crucial safety feature, as it helps to avoid unnecessary shutdowns or incorrect readings that could lead to misinterpretation of the machinery’s condition.

Flexible Mounting Options

The availability of both din – rail clips and bulkhead mounting screws as standard options makes it easy to install the transmitter in different types of industrial setups. Whether in a control panel or directly on the machinery itself, the 991 transmitter can be mounted securely and conveniently.

Function

The main function of the 991-01-XX-01-00 MOD: 284318 – 01 is to accurately measure the axial displacement of a rotating shaft. It takes the input from the 3300 nsv proximity probe, which detects the position of the shaft relative to a fixed reference point. The transmitter then processes this raw signal, applying necessary conditioning and conversion algorithms to transform it into a 4 – 20 mA signal that is proportional to the axial displacement. This output signal is then sent to the machinery control system. In the control system, this signal is used for multiple purposes. It can trigger alarms if the measured thrust exceeds pre – set limits, indicating potential problems such as bearing wear or misalignment. It can also be used in control logic to adjust the operation of the machinery, for example, to optimize the performance of a compressor by maintaining the correct axial position of the shaft.

Use

In industrial applications, the 991 thrust transmitter is installed in close proximity to the rotating shaft of the machinery. The 3300 nsv proximity probe is carefully positioned to detect the axial movement of the shaft. The transmitter is then connected to the probe via the appropriate extension cable. Once installed, it is powered up using the specified +12 to +35 VDC power supply. Engineers and technicians use Bently Nevada’s recommended tools and procedures to configure the zero and span settings of the transmitter according to the specific requirements of the machinery. The output 4 – 20 mA signal is then connected to the machinery control system, where it is integrated into the overall monitoring and control strategy. Maintenance teams regularly check the transmitter’s diagnostic outputs and perform tests using the test input pin to ensure its continued accurate operation.

Application Fields

Centrifugal Air Compressors

Essential for monitoring the axial displacement of the compressor shaft. By accurately measuring thrust, it helps to prevent compressor failures due to excessive axial loads, which could lead to damaged bearings, seals, and impellers. This ensures the efficient and reliable operation of the compressor, which is critical for processes such as air supply in industrial plants, refrigeration systems, and gas pipelines.

Small Pumps

Used to monitor the shaft’s axial movement in small pumps. This is important for maintaining the proper alignment of the pump’s impeller and casing, preventing wear and tear on the mechanical components. In applications such as water supply systems, chemical transfer pumps, and oil – well pumps, the accurate measurement of thrust by the 991 transmitter can help to extend the pump’s lifespan and improve its performance.

Motors

In motor applications, the 991 transmitter can detect any abnormal axial displacement of the motor shaft. This information is valuable for preventing motor failures caused by misalignment or bearing problems. Motors are used in a wide range of industries, from manufacturing and processing plants to transportation systems, and ensuring their reliable operation is crucial for overall productivity.

Fans

For fans, especially those in industrial ventilation systems or cooling towers, monitoring the axial displacement of the fan shaft is important. The 991 thrust transmitter can help to identify any issues that could lead to fan imbalance, such as bearing wear or improper installation. By preventing fan failures, it ensures the proper functioning of ventilation and cooling systems, which are essential for maintaining a safe and comfortable working environment in industrial facilities.

In conclusion, the Bently Nevada 991-01-XX-01-00 MOD: 284318 – 01 thrust transmitter is a highly reliable and accurate device for measuring axial displacement in industrial machinery. Its advanced features, wide range of applications, and compatibility with other Bently Nevada products make it an ideal choice for OEMs and end – users looking to enhance the performance and reliability of their machinery.