Introduction to the 991-06-70-02-CN Thrust Transmitter
When axial shaft position drifts beyond safe limits, the 991-06-70-02-CN from Bently Nevada provides a reliable early warning. This probe vibration transmitter is engineered for thrust monitoring, converting proximity probe signals into a standard 4-20 mA output. As a model 991 thrust transmitter, it is designed for continuous duty in industrial rotating machinery.
Key Features and Technical Specifications
The 991-06-70-02-CN offers a full-scale range of 0.6-0-0.6 mm, suitable for 25-0-25 mils current loop linear ranges. Its linear range for proximity output is 0.25 to 1.65 mm. The transmitter operates on a +12 to +35 Vdc input at the terminal, ensuring compatibility with common industrial power supplies.
- Output signal: 4-20 mA in a 2-wire configuration
- Loop accuracy: within ±1.5% over the specified full-scale range (typical)
- Maximum loop resistance: 1,000 Ω including cable at 35 Vdc
- Current limiting: 23 mA typical
- Zero and span: non-interacting external adjustments
- Not OK/Signal Defeat: output goes to less than 3.6 mA within 100 µs after a Not OK condition
Applications and Use Cases
The 991-06-70-02-CN is primarily used for axial thrust monitoring in turbines, compressors, and large pumps. Its DIN rail mounting simplifies installation in control cabinets. The 4-20 mA output integrates directly with PLCs, DCS, and SCADA systems, reducing the need for additional signal conditioning.
Installation and Setup
Mount the transmitter on a standard DIN rail. Connect the 3300 NSv proximity probe and extension cable to the input. Apply +12 to +35 Vdc at the transmitter terminal. Adjust zero and span using the external non-interacting adjustments. Ensure the loop resistance does not exceed 1,000 Ω at 35 Vdc.
Maintenance and Reliability
Regularly inspect the transmitter and probe cable for physical damage. Verify the 4-20 mA output matches the expected thrust position. The operating temperature range of -35°C to +85°C ensures reliable performance in harsh environments. The Not OK/Signal Defeat feature provides fast fault indication, aiding in predictive maintenance.
Compatibility and Integration
The 991-06-70-02-CN accepts one non-contacting 3300 NSv proximity probe. Its 4-20 mA output is universally compatible with most control systems. The bulkhead screw mounting option secures the probe connection, and the 7.0 meter (23.0 feet) system length provides installation flexibility.
Troubleshooting and Common Issues
If the output is below 3.6 mA, check for a Not OK condition such as probe damage or cable disconnection. Verify the supply voltage is within +12 to +35 Vdc. Confirm the loop resistance is within the 1,000 Ω limit. For persistent issues, consult the Bently Nevada manual or contact AutoDCSTech.
Product Support and Availability
The 991-06-70-02-CN is available from AutoDCSTech. Contact us for current lifecycle status and availability before ordering. We are ready to assist with your industrial automation needs.
