Bently Nevada 991-25-70-02-CN Thrust Transmitter

Bently Nevada 991-25-70-02-CN Thrust Transmitter

Product Introduction

The Bently Nevada 991-25-70-02-CN is a specialized 2-wire thrust transmitter. It continuously monitors the axial position of rotating machinery shafts like turbines and compressors. This model accepts input from a single 3300 NSv proximity probe. It translates shaft thrust movement into a proportional 4-20 mA signal for easy system integration. Its compact design and robust construction suit various industrial applications. Specifically, this version offers a 25-0-25 mils range and includes CN country-specific approvals.

Key Technical Specifications

This section outlines the essential parameters of the Bently Nevada 991 transmitter. These specifications guide proper application and ensure reliable operation.

• Input: The unit accepts one non-contacting 3300 NSv Proximity Probe along with its matching extension cable.

• Power Supply: It requires a DC input voltage between +12 and +35 Vdc applied at the transmitter terminal.

• Signal Output: It delivers a standard 4 to 20 mAdc signal across its specified full-scale range. This uses a 2-wire configuration for simplicity.

• Loop Accuracy: The 991-25-70-02-CN maintains loop accuracy within ±1.5% typical. Bently Nevada rates this from the TEST signal input across a 250 Ω load.

• Linear Range: The linear range spans 0.25 to 1.65 mm for Prox Out. This suits the 25-0-25 mils current loop linear range.

• Current Limiting: The typical current limiting is set at 23 mA. This protects the loop wiring and connected instruments from overcurrent faults.

• NOT OK/Signal Defeat: The output drops below 3.6 mA within 100 µs of a Not OK condition. It automatically restores within 0.1 seconds after the fault clears.

Mechanical and Environmental Specifications

The physical attributes and environmental limits are crucial for installation. The 991 Thrust Transmitter is built for longevity in harsh settings.

• Transmitter Weight: It weighs only 0.43 kg (0.9 lbm). This lightweight design simplifies mounting and reduces stress on the mounting hardware.

• Mounting: The unit mounts on a standard DIN rail for secure installation.

• Mounting Option: The specific 02 option includes bulkhead screws for robust panel mounting.

• Operating Temperature: The transmitter operates reliably from -35°C to +85°C (-31°F to +185°F).

• Storage Temperature: It can be stored from -51°C to +100°C (-60°F to +212°F) without damage.

• Agency Approval: The CN option signifies country-specific approvals for this model.

Installation and Connection Guide

Proper installation is key for the Bently Nevada 991-25-70-02-CN to function correctly. Follow these guidelines for a successful setup.

First, securely mount the transmitter on a DIN rail using the bulkhead screws. Ensure the mounting surface is stable and free from excessive vibration. Next, connect the 3300 NSv proximity probe and its extension cable to the input. Subsequently, wire the power supply to the transmitter terminals. A +12 to +35 Vdc source is mandatory.

After that, wire the 4-20 mA loop. The maximum loop resistance must not exceed 1,000 Ω at 35 Vdc. This includes all cable resistance. Finally, set the probe gap within the linear range of 0.25 to 1.65 mm. Use the non-interacting external adjustments for zero and span. This will ensure accurate measurement across the specified 25-0-25 mils range.

Packaging and Delivery

Your order will be carefully packaged to prevent damage during transit. All items are shipped from our warehouse promptly.

Packaging List:

• 1 x Bently Nevada 991-25-70-02-CN Thrust Transmitter

• 1 x Bulkhead screw mounting kit

• 1 x Installation guide (quick start)

Shipping: We use major couriers for reliable worldwide delivery.

• Fedex

• UPS

• DHL

Frequently Asked Questions (FAQ)

1. What is the full-scale range of the 991-25-70-02-CN?
The 991-25-70-02-CN has a full-scale range of 25-0-25 mils. This bi-directional range suits axial thrust measurement applications.

2. What does the 'CN' agency approval option mean for this model?
The CN option indicates country-specific approvals. This ensures the 991 Thrust Transmitter complies with local regulatory requirements for the intended region.

3. How does the 991 series differ from the 990 series?
The 990 series measures radial vibration. The 991 series is specifically designed for axial thrust monitoring. Both use the 3300 NSv probe but have different calibrations.

4. What is the significance of the 'System Length' option '70'?
The '70' in the model number 991-25-70-02-CN specifies a system length of 7.0 meters (23.0 feet). This refers to the total length of the probe and extension cable system.

5. How quickly does the transmitter recover from a Not OK condition?
The output drops below 3.6 mA within 100 µs of a Not OK condition. It automatically restores within 0.1 seconds after the fault clears, ensuring rapid system recovery.