Description
Application Scenarios
A centrifugal air compressor OEM in Southeast Asia faced a recurring challenge with its packaged compressor units: end users required basic thrust position monitoring for the fluid-film thrust bearings, but the cost and cabinet space associated with full 3500 rack-based monitoring systems made the offering commercially uncompetitive against lower-cost competitors. The OEM needed a simple, reliable solution that could be integrated directly into the existing PLC panel without adding rack infrastructure.
By integrating the 991-10-XX-02-00 thrust transmitter into each compressor package, the OEM achieved direct 4-20 mA thrust position signals fed into the PLC’s analog input cards, triggering alarm and shutdown logic when axial displacement exceeded safe limits. The 163930-01 modification ensures compatibility with the 3300 NSv probe ecosystem, allowing the same probe technology already used for vibration monitoring to serve thrust measurement as well. Since deployment, field failures due to undetected thrust bearing wear have been eliminated across the installed fleet, and the OEM has reduced per-unit monitoring hardware costs by eliminating the need for dedicated rack-based thrust cards.
Parameter
| Parameter | Value/Description |
|---|---|
| Product Model | 991-10-XX-02-00 |
| Modification Part Number | 163930-01 |
| Manufacturer | Bently Nevada (Baker Hughes) |
| Product Category | Thrust Transmitter (Axial Position) |
| Full-Scale Range | 0-10 mils pp (0-250 μm pp) |
| Input Sensor | 3300 NSv Proximity Probe with extension cable |
| System Length Options | 5.0 m or 7.0 m (16.4 ft / 23.0 ft) |
| Output Signal | 4-20 mA, 2-wire, loop-powered |
| Power Supply | +12 to +35 VDC |
| Loop Accuracy | ±1.5% of full scale |
| Maximum Loop Resistance | 1,000 Ω at 35 VDC |
| Operating Temperature | -35°C to +85°C (-31°F to +185°F) |
| Mounting Option | Bulkhead screw mounting (-02 suffix) |
| Physical Dimensions | 100.1 × 73.9 × 53.3 mm |
| Weight | 0.43 kg |
Technical Principles and Innovative Values
Innovation Point 1: Integrated Proximitor Sensor Eliminates External前置器. Unlike traditional proximity probe systems that require a separate Proximitor sensor unit mounted in a cabinet, the 991-10-XX-02-00 integrates the Proximitor function directly into the transmitter housing. This eliminates one active component from the signal chain, reduces wiring complexity, and removes a common failure point in harsh compressor environments where cabinet space is at a premium.
Innovation Point 2: 3300 NSv Probe Compatibility in Minimal Clearance. The 991 Thrust Transmitter is specifically designed to work with the 3300 NSv proximity probe, whose small physical size allows installation in tight axial measurement locations typical of centrifugal air compressors. The 991-10-XX-02-00 with modification 163930-01 preserves this compatibility, enabling thrust measurement in applications where larger traditional probes simply cannot fit.
Innovation Point 3: Not OK/Signal Defeat Circuit Prevents False Trips. A critical reliability feature of the 991-10-XX-02-00 is its signal defeat circuit. When a faulty probe or loose connection is detected, the output drives below 3.6 mA within 100 microseconds, allowing the control system to distinguish between a genuine high-thrust condition and a sensor fault. This prevents false alarms and unnecessary shutdowns that would otherwise erode operator confidence in the monitoring system.
Innovation Point 4: Potted Construction for Condensing Environments. The 163930-01 variant is encapsulated with a potted construction rated for 100% condensing humidity. In compressor installations where ambient moisture and oil mist are unavoidable, this design prevents internal corrosion and signal drift that plague non-potted transmitters over extended service intervals.
