Steam turbines are instrumented with dozens of sensors monitoring vibration, temperature, pressure, speed, and position. These instruments provide the data for protection systems (automatic trip on abnormal conditions) and for condition-based maintenance diagnostics. Sensor reliability is therefore both a safety and an economic requirement.
AQ Process Systems sources and exports replacement sensors and transmitters for all turbine monitoring parameters, from shaft vibration probes and bearing thermocouples to valve position transducers and casing expansion sensors. We support Bently Nevada, Emerson, SKF, Meggitt, and OEM-supplied instrumentation systems.
Carrying critical spare instruments on-site is essential, a failed vibration probe or bearing thermocouple can force a turbine load reduction or shutdown if there is no redundant channel. We supply complete spare sensor kits tailored to your turbine configuration.
| Component | Specification | Description |
|---|---|---|
| Vibration Monitoring | ||
| Proximity Probes (Eddy Current) | 8mm or 5mm tip | API 670 compliant | Various cable lengths | Shaft vibration and position monitoring probes, non-contacting eddy current type for radial vibration and axial displacement. |
| Proximitors / Driver Modules | -24VDC powered | Signal conditioning | Signal conditioning modules converting proximity probe impedance changes to calibrated voltage outputs. |
| Accelerometers | ICP/IEPE | Casing vibration | Various sensitivity | Piezoelectric accelerometers for casing vibration monitoring, housing-mounted for detecting bearing defects and structural resonance. |
| Extension Cables | Matched impedance | Armoured | Various lengths | Probe extension cables with controlled impedance, matched to the probe-proximitor system for correct calibration. |
| Temperature Monitoring | ||
| Bearing RTDs | Pt100 | Embedded in babbitt | 3 or 4 wire | Resistance temperature detectors embedded in bearing metal, the primary bearing condition indicator. |
| Steam Temperature Thermocouples | Type K or Type N | With thermowell | HP/IP/LP steam | Thermocouples monitoring steam temperatures at turbine inlet, extraction points, and exhaust. |
| Casing Expansion Sensors | LVDT or linear potentiometer | Casing-to-foundation | Differential expansion sensors measuring relative movement between the rotor, casing, and foundation. |
| Pressure & Position | ||
| Pressure Transmitters | Gauge or absolute | 4-20mA / HART | SS wetted | Electronic pressure transmitters for steam inlet, extraction, exhaust, and oil system pressure monitoring. |
| Valve Position Transducers | LVDT or rotary encoder | Feedback to governor | Position feedback sensors on main stop valves and governor valves, providing valve position to the control system. |
| Speed Probes | Magnetic pickup or eddy current | Redundant installation | Speed sensors for governing, synchronisation, and overspeed protection, typically installed in triplicate for voting logic. |
Parts are manufactured to OEM specifications with full material certification, dimensional inspection, and NDE documentation as required. Provide the turbine manufacturer, frame/model designation, and part number for precise identification.
Critical on-site spares include proximity probes (at least 2), proximitors, bearing RTDs (2-4), speed sensors (1-2), a valve position transducer, and pressure transmitters. These are the instruments most likely to fail and most likely to cause a turbine load reduction or trip if a redundant channel is not available.
Proximity probes have no moving parts and can last 10-20 years, but degradation of the probe tip and cable insulation can cause drift. Best practice is to replace probes during major overhauls (every 4-6 years) as a preventive measure. Verify probe gap and system calibration during every outage.
Yes. We supply proximity probes, proximitors, extension cables, and accelerometers compatible with Bently Nevada 3300, 3500, and legacy 7200 series monitoring systems. We also supply compatible probes for Emerson (CSI), SKF, and Meggitt systems. Probes meet API 670 requirements.
Differential expansion is the difference in thermal growth between the turbine rotor (which heats up quickly) and the casing (which heats up slowly). Excessive differential expansion can cause blade tip rubbing, seal contact, and reduced clearances. The sensor measures this difference and provides alarm/trip protection during startup and load changes.
Yes. We can assemble a custom spare sensor kit based on your turbine model and installed instrumentation system, including all vibration probes, RTDs, thermocouples, speed sensors, and pressure transmitters with the correct cable lengths, connectors, and mounting hardware. Contact us with your turbine details for a tailored spare kit quotation.
Share your turbine make, model, and part numbers, we respond within 24 hours.