Bently Nevada 991-25-50-01-00 Thrust Transmitter 5m Cable

Bently Nevada 991-25-50-01-00 Thrust Transmitter

Product Introduction

The Bently Nevada 991-25-50-01-00 is a versatile axial position transmitter from the 991 series, specifically configured for thrust monitoring applications. This model provides a bi-polar measurement range of 25-0-25 mils, capturing both forward and reverse shaft displacement from a neutral reference point. It pairs with a single 3300 NSv proximity probe to deliver a standardized 4-20 mA loop output. Additionally, the system length of 5.0 meters (16.4 feet) offers sufficient reach for many machine configurations. This version carries Agency Approval Option 00, meaning no hazardous area certifications are required, making it ideal for general-purpose industrial environments.

Key Technical Specifications

The 991-25-50-01-00 delivers accurate and repeatable axial position data critical for thrust bearing protection. Its primary function is to accept input from one non-contacting 3300 NSv proximity probe and extension cable, then condition that raw signal into a two-wire, 4-20 mA output.

• Input: Accepts 1 non-contacting 3300 NSv Proximity Probe and extension cable.

• Power Supply: Requires +12 to +35 Vdc input at the transmitter terminal.

• Output Signal: 4 to 20 mAdc over the specified full-scale bi-polar range (25-0-25 mils).

• Linear Range: 0.25 to 1.65 mm for Prox Out. Suitable for 0.6-0-0.6 mm or 25-0-25 mils current loop linear ranges.

• Loop Accuracy: Within ±1.5% over the full-scale range (typical), measured from TEST signal to a 250 Ω load.

• Maximum Loop Resistance: 1,000 Ω including cable at 35 Vdc.

• Current Limiting: 23 mA typical.

• Zero and Span: Non-interacting external adjustments for independent calibration.

Mechanical and Environmental Specifications

This transmitter is engineered to perform reliably across a wide temperature range, making it suitable for demanding industrial settings.

• Mounting Option: 01 – 35 mm DIN-rail clips for cabinet installation.

• System Length Option: 50 – 5.0 meters (16.4 feet) total cable length.

• Transmitter Weight: 0.43 kg (0.9 lbm).

• Operating Temperature: -35°C to +85°C (-31°F to +185°F).

• Storage Temperature: -51°C to +100°C (-60°F to +212°F).

• Agency Approval Option: 00 – Not required; intended for non-hazardous, general-purpose areas.

Installation and Setup Instructions

Proper installation ensures accurate thrust measurement and long-term reliability. First, mount the Bently Nevada 991-25-50-01-00 onto a standard 35 mm DIN rail using the included clips. Next, connect the 3300 NSv probe and extension cable to the transmitter input. Then, carefully gap the probe tip between 0.25 and 1.65 mm from the target surface to achieve the 25-0-25 mils bi-polar range.

For the output wiring, configure a 2-wire current loop with a DC power supply between +12 and +35 Vdc. Additionally, confirm that the total loop resistance—including cables and receiving instruments—does not exceed 1,000 Ω at 35 Vdc. The 991-25-50-01-00 features non-interacting zero and span potentiometers, allowing you to set the 4 mA and 20 mA points independently. This is particularly important for bi-polar applications where 12 mA typically represents the neutral shaft position.

Built-In Diagnostic Features

This transmitter includes a "Not OK" signal defeat function to enhance system reliability. When a fault condition occurs—such as a probe disconnect or internal error—the output current drops below 3.6 mA within 100 µs. Consequently, your control system can immediately recognize the failure and take appropriate protective action. Once the fault is cleared, the output automatically recovers within 0.1 seconds. This rapid restoration minimizes downtime and simplifies troubleshooting in critical thrust monitoring applications.

Packaging List

• 1 x Bently Nevada 991-25-50-01-00 Thrust Transmitter

• 35 mm DIN-rail mounting clips (pre-installed)

• Quick-start installation guide

Please note: The 3300 NSv proximity probe, extension cable, and external power supply must be ordered separately.

Shipping Information

All orders are dispatched via FedEx, UPS, or DHL to ensure prompt and secure delivery. Contact our team for real-time stock levels and estimated shipping times.

Frequently Asked Questions (FAQ)

1. What is the measurement range of the 991-25-50-01-00?
This transmitter measures bi-polar axial displacement from -25 mils to +25 mils, with a neutral center at 0 mils. The 25 full-scale option defines this specific range, which is standard for thrust bearing monitoring in turbines and compressors.

2. Does the 991-25-50-01-00 have hazardous area approvals?
No. This version carries Agency Approval Option 00, meaning it has no hazardous location certifications. It is intended for general-purpose, non-hazardous industrial environments only.

3. What is the difference between the 5.0m and 7.0m system length options?
The System Length Option 50 provides 5.0 meters (16.4 feet) of total cable length, while Option 70 provides 7.0 meters (23.0 feet). Choose based on the distance between your probe connection point and the transmitter mounting location.

4. Can I use this transmitter with a probe other than the 3300 NSv?
The Bently Nevada 991-25-50-01-00 is specifically calibrated for the 3300 NSv proximity probe and its matching extension cable. Using other probes will compromise accuracy and may damage the input circuitry.

5. How do I calibrate the zero and span on the 991-25-50-01-00?
The transmitter features non-interacting external zero and span adjustments. For a bi-polar 25-0-25 mils range, set the 12 mA (midpoint) to represent the neutral shaft position, then adjust span to achieve 4 mA at -25 mils and 20 mA at +25 mils. Always refer to the product manual for the complete calibration procedure.