Product Overview
The Bently Nevada 991-25-50-02-00 is a Probe Vibration Transmitter designed for axial thrust measurement in rotating machinery. Part of the trusted 991 series, this Thrust Transmitter converts proximity probe signals into a linear 4-20 mA output, enabling continuous monitoring of shaft position. Ideal for replacing older analog systems, the 991-25-50-02-00 delivers reliable performance in harsh industrial environments, supporting predictive maintenance and reducing unplanned downtime.
Technical Specifications
The 991-25-50-02-00 offers precise measurement capabilities with the following key parameters:
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Power Supply: +12 to +35 Vdc at the transmitter terminal
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Output Signal: 4-20 mA, 2-wire configurable
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Loop Accuracy: ±1.5% of full scale (typical)
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Linear Range: 0.25 to 1.65 mm (Prox Out); supports 0.6-0-0.6 mm or 25-0-25 mils current loop
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Maximum Loop Resistance: 1,000 Ω at 35 Vdc
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Current Limiting: 23 mA typical
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Operating Temperature: -35°C to +85°C
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Storage Temperature: -51°C to +100°C
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Weight: 0.43 kg (0.9 lbm)
This transmitter accepts one non-contacting 3300 NSv proximity probe and extension cable, with non-interacting zero and span adjustments for easy calibration.
Industry Applications
The Bently Nevada 991-25-50-02-00 is primarily used in steam turbines, compressors, and large rotating equipment to monitor axial shaft position. Typical applications include:
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Power Generation: Monitoring turbine thrust bearings to prevent catastrophic failure.
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Oil & Gas: Protecting centrifugal compressors from axial displacement.
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Industrial Machinery: Providing continuous feedback for process control systems.
With its fast Not OK/Signal Defeat response (less than 3.6 mA within 100 µs), the 991-25-50-02-00 enhances safety by quickly signaling fault conditions.
Installation & Setup Guidance
Mount the 991-25-50-02-00 on a DIN rail using the bulkhead screws provided (Mounting Option 02). The system length is 5.0 meters (16.4 feet) – ensure proper cable routing. Connect the 3300 NSv probe and extension cable to the input. Wire the 4-20 mA loop to the control system, observing polarity. Set zero and span via external potentiometers. Verify loop resistance does not exceed 1,000 Ω at 35 Vdc. Use a 250 Ω resistor for accuracy verification.
Maintenance & Reliability
The 991-25-50-02-00 requires minimal maintenance. Periodically check for cable damage and connector integrity. Clean the probe face if oil or debris accumulation is possible. The wide operating temperature range (-35°C to +85°C) ensures reliability in extreme conditions. Regular calibration checks (annually recommended) maintain ±1.5% accuracy. Storing the unit within -51°C to +100°C when not in use extends service life.
Selection Guide & Purchasing Advice
Before purchasing the Bently Nevada 991-25-50-02-00, verify your system requirements: the full-scale option (-25 = 25-0-25 mils) and system length (-50 = 5.0 meters) match your application. Ensure compatibility with existing 3300 NSv probes and control systems that accept 4-20 mA inputs. For technical support and fast delivery, source from trusted suppliers like PLC Source PRO (available at ubest101.myshopify.com). Our team can confirm part variants and provide documentation.