The governing system maintains turbine speed within safe limits and controls power output by regulating steam admission. Modern turbines use electronic governors with hydraulic actuators, while older units may have mechanical-hydraulic governors. Both require periodic maintenance and spare parts replacement.
AQ Process Systems sources and exports speed sensors, servo valves, hydraulic actuator components, control oil pumps, trip solenoids, and overspeed protection devices for all major turbine governing system configurations. We support both retrofit of older mechanical systems and maintenance of modern digital controls.
Governor system reliability is a safety-critical requirement, a failure in speed control or overspeed protection can lead to catastrophic turbine failure. All control system spares we supply meet the stringent quality requirements of turbine protection applications.
| Component | Specification | Description |
|---|---|---|
| Speed Sensing | ||
| Speed Sensors / Pickups | Magnetic, eddy current, or optical | Various mounting | Turbine speed sensors providing the primary speed signal for governing, synchronisation, and overspeed protection. |
| Speed Sensor Targets | Toothed wheel or notched disc | Shaft-mounted | Rotor-mounted speed reference targets, toothed wheels generating the pulse signal for speed sensors. |
| Overspeed Trip Bolts | Mechanical | Centrifugal trip mechanism | Mechanical overspeed trip bolt assemblies, centrifugally-actuated backup overspeed protection independent of the electronic system. |
| Hydraulic Control | ||
| Electro-Hydraulic Servo Valves | 2-stage or 3-stage | Proportional control | Precision servo valves converting electronic control signals to hydraulic actuator movement for valve positioning. |
| Control Oil Pumps | Gear or screw type | Shaft-driven or motor-driven | Hydraulic oil supply pumps providing pressurised control oil for valve actuators and trip systems. |
| Hydraulic Accumulators | Bladder or piston type | Trip oil stored energy | Pressurised accumulators providing stored energy for rapid valve closure during turbine trip events. |
| Control Oil Filters | Duplex | 10 micron absolute | With bypass | High-quality oil filtration protecting servo valves from contamination, duplex arrangement for online changeout. |
| Trip & Protection | ||
| Trip Solenoids | Fast-acting | De-energise to trip (fail-safe) | Solenoid valves in the trip oil circuit, de-energising dumps trip oil pressure and closes the main stop valve. |
| Trip Oil Relay Valves | Hydraulic | Fast-acting dump valves | Relay valves amplifying the trip solenoid signal for rapid draining of the actuator oil circuit. |
| Emergency Trip Handles | Manual | Mechanical linkage to trip valve | Local manual trip handles for emergency turbine shutdown from the turbine floor, independent of all electronic systems. |
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.
The most frequently replaced items are speed sensors (electromagnetic degradation), servo valves (contamination and internal leakage), control oil filters (scheduled replacement), trip solenoids (function testing and preventive replacement), hydraulic seals in actuators, and control oil pump wear parts. Mechanical overspeed trip bolts require periodic testing and resetting.
Speed sensors should be functionally tested during every planned outage. Preventive replacement every 5-8 years is common practice, though sensors in high-vibration or high-temperature environments may need more frequent replacement. Always carry a spare sensor on-site for emergency replacement.
Yes. We supply 2-stage and 3-stage electro-hydraulic servo valves for turbine governor systems, compatible with Woodward, Moog, Bosch Rexroth, and OEM-specific designs. Servo valve contamination is the most common cause of governor hunting and instability, we also supply the high-quality control oil filters that protect them.
The mechanical overspeed trip is a centrifugally-actuated bolt or ring mounted on the turbine rotor that triggers at approximately 110% rated speed. It acts as a completely independent backup to the electronic overspeed protection, if the electronic system fails to trip the turbine, the mechanical device will. It is tested during every planned outage.
We can supply components for upgrading older mechanical-hydraulic governors to modern electronic-hydraulic systems, including the electronic controller, servo valves, speed sensors, actuators, and wiring. We work with Woodward, ABB, and other control system specialists for complete retrofit solutions.
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