Introduction to the 991-25-70-03-CN Bently Nevada Thrust Transmitter
When you need reliable axial position monitoring, the 991-25-70-03-CN from Bently Nevada provides a robust solution. This probe vibration transmitter converts proximity probe signals into a standard 4-20 mA output, enabling seamless integration with your control systems. Designed for thrust measurement, it ensures accurate data for critical machinery protection.
Key Features and Technical Specifications
The 991-25-70-03-CN is engineered for precision and durability. Below are its essential specifications:
- Output Signal: 4-20 mA, two-wire configuration
- Power Requirement: +12 to +35 Vdc at the transmitter terminal
- 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
- Full-Scale Option: -25 = 25-0-25 mils
- System Length: -70 = 7.0 meters (23.0 feet)
- Mounting: DIN rail with clips and screws
- Operating Temperature: -35°C to +85°C
- Storage Temperature: -51°C to +100°C
- Weight: 0.43 kg (0.9 lbm)
One distinctive feature is the Not OK/Signal Defeat function. When a Not OK condition occurs, the output drops to less than 3.6 mA within 100 µs, and it restores within 0.1 seconds after the condition clears. This rapid response enhances system safety by alerting operators immediately.
Applications and Use Cases
The 991-25-70-03-CN is primarily used for axial thrust measurement in rotating machinery such as turbines, compressors, and pumps. Its 4-20 mA output makes it compatible with most PLCs, DCS, and SCADA systems. For example, in a steam turbine, this transmitter monitors rotor axial displacement, helping prevent catastrophic thrust bearing failure. Its DIN rail mounting simplifies installation in existing panels, reducing downtime.
Installation and Setup
Mounting the 991-25-70-03-CN is straightforward with the included DIN clips and screws. Ensure the transmitter is mounted on a standard DIN rail in a clean, dry enclosure. Connect the power supply (+12 to +35 Vdc) to the transmitter terminal, and wire the 4-20 mA output to your monitoring system. The system length of 7.0 meters (23.0 feet) provides flexibility for probe placement. Always follow the manufacturer's manual for detailed wiring diagrams and torque specifications.
Maintenance and Reliability
To maintain reliable operation, inspect the transmitter periodically for signs of physical damage or loose connections. Check the probe and extension cable for wear, especially in high-vibration environments. The operating temperature range of -35°C to +85°C ensures performance in harsh conditions. Regular verification of the 4-20 mA loop accuracy (within ±1.5% typical) is recommended. For any issues, consult the Bently Nevada documentation or contact AutoDCSTech for support.
Compatibility and Integration
The 991-25-70-03-CN accepts one non-contacting 3300 NSv proximity probe and extension cable. Its 4-20 mA output integrates easily with standard analog input modules. The maximum loop resistance is 1,000 ohms at 35 Vdc, allowing long cable runs. The zero and span adjustments are non-interacting, simplifying calibration. This transmitter is ideal for retrofitting older systems that require a 4-20 mA interface.
Troubleshooting Common Issues
If the output signal is not within the expected range, first verify the power supply voltage is between +12 and +35 Vdc. Check the probe gap and ensure it is within the linear range. If the output goes below 3.6 mA, a Not OK condition may be present; inspect the probe and cable for faults. Use a multimeter to measure the loop current and compare it with the expected value. For persistent issues, refer to the troubleshooting section of the Bently Nevada manual.
Product Support and Availability
The 991-25-70-03-CN is available from AutoDCSTech. As an industrial automation parts supplier, we ensure genuine Bently Nevada products. Please verify current lifecycle status and availability with AutoDCSTech before ordering. For technical inquiries, contact our team for expert assistance.
