Solving Axial Vibration Monitoring Challenges
When a rotating machine experiences unexpected thrust movement, the consequences can be severe. The 991-06-70-01-01 from Bently Nevada addresses this challenge directly. This probe vibration transmitter converts proximity probe signals into a standard 4-20 mA output, enabling continuous axial position monitoring. Engineers rely on this device to detect thrust bearing wear and prevent catastrophic failures.
Designed for axial measurement, the 991-06-70-01-01 accepts one non-contacting 3300 NSv proximity probe and extension cable. Its linear range of 0.25 to 1.65 mm for Prox Out makes it suitable for 0.6-0-0.6 mm or 25-0-25 mils current loop linear ranges. This flexibility allows integration into various monitoring systems.
Key Features and Technical Specifications
The 991-06-70-01-01 offers several features that enhance its reliability and ease of use:
- Output signal: 4-20 mA in a 2-wire configuration over the specified full-scale range.
- Power requirement: +12 to +35 Vdc input at the transmitter terminal.
- Maximum loop resistance: 1,000 ohms including cable at 35 Vdc.
- Current limiting: 23 mA typical.
- Zero and span: non-interacting external adjustments for easy calibration.
- Not OK/Signal Defeat: output drops to less than 3.6 mA within 100 µs after a Not OK condition.
Accuracy is rated within ±1.5% over the specified full-scale range (typical), measured from the TEST signal input to the voltage across a 250-ohm loop resistance. This precision ensures reliable data for critical machinery protection.
Installation and Mounting Flexibility
The 991-06-70-01-01 mounts on a standard 35 mm DIN rail using the included clips (Mounting Option 01). This simplifies installation in existing panels. The system length option -70 provides a 7.0-meter (23.0 feet) cable, accommodating typical machine layouts. The transmitter operates in temperatures from -35°C to +85°C, making it suitable for harsh industrial environments.
For setup, the non-interacting zero and span adjustments allow quick commissioning. The 4-20 mA loop connects in a standard 2-wire configuration, reducing wiring complexity. Always follow the manufacturer's manual for precise wiring and configuration steps.
Applications and Use Cases
The 991-06-70-01-01 is ideal for axial position monitoring in turbines, compressors, and large pumps. In these applications, thrust bearing health is critical. By providing a continuous 4-20 mA signal, the transmitter enables integration with PLCs, DCS, and SCADA systems. This allows operators to trend axial movement and set alarms before damage occurs.
For example, in a steam turbine, the transmitter monitors rotor axial displacement. If the rotor shifts beyond safe limits, the Not OK function forces the output below 3.6 mA, triggering an alarm. This rapid response helps prevent costly downtime.
Maintenance and Reliability
Regular inspection of the 991-06-70-01-01 ensures long-term performance. Check the probe and cable for physical damage. Verify the loop power supply stays within +12 to +35 Vdc. Periodically test the Not OK function to confirm proper operation. Because the transmitter is rated for CSA Division 2 hazardous locations, it suits many industrial areas. Follow the manufacturer's safety guidelines during any maintenance.
Compatibility and Integration
The 991-06-70-01-01 works with Bently Nevada 3300 NSv proximity probes. Its 4-20 mA output interfaces directly with most control systems. The 2-wire configuration simplifies integration. For systems requiring higher loop resistance, the transmitter supports up to 1,000 ohms at 35 Vdc, ensuring compatibility with long cable runs.
Product Support and Availability
The 991-06-70-01-01 is available through AutoDCSTech. As an industrial automation parts supplier, AutoDCSTech ensures genuine Bently Nevada products. Contact them for current availability and lifecycle status. Please verify the product's lifecycle and stock before ordering.
