- Spiral Case.
This spiral case is directly connected to the penstock at a point with the same diameter, this tool is installed around the turbine with a diameter that is getting smaller and smaller (like a cochlea) in order to be able to provide even working pressure to the turbine blades.
On the inside of the spiral case, Stay Rings are installed which are meant to guide the flow of water right into the wicket gates, and also have a door for maintenance inspection.
- Stay Ring.
Consists of blades (20 pieces) which are welded on the inside of a spiral case which is used to guide the flow of water so that it enters the wicket gate precisely and three of the blades have holes for the passage of waste water from the turbine head cover.
- Wicket Gates.
These 20 gates are used to control the flow of water into the turbine runner, so they are located between the stay ring and the turbine runner, and are perpendicular to the head cover and bottob ring. Full opening is 18.6 cm. 492.8 mm high.
If the gates are closed, the stainless steel joints of each of these gates will actually meet tightly so that water cannot escape at all.
- Bottom Ring or Lower Ring.
Located between the stay ring and the draft tube which has bushes that can guide the lower axis of the wicket gate. (Where the holder is the bottom axis of the wicket gate)
The lower ring is bolted to the stay ring and also to the draft tube, so there is no chance of leaking from here.
- Head Cover.
As a cover for the turbine runner and wicket gates, it has bushes for the upper shaft wicket gate and above that there are bushes water seals to prevent water from entering the turbine pit and also has three drain holes that penetrate the stay ring blades and are wasted into the drainage sump.
- Turbine Shaft.
It is the main axis for sending the power generated by the turbine to the generator where there is a change from mechanical power to electric power.
Underneath this main shaft is bolted with a turbine runner and on top of that the thrust block and generator rotor are also bolted, and a connection shaft called the upper shaft is also installed.
- Shaft Seal.
It is located above the turbine runner through the head cover and its surface is attached to the shaft sleeve.
In order to prevent the air draft tube from flowing into the turbine pit.
- Shaft Sleeve.
Made of stainless steel and bolted around the main shaft where the surface collides with the shaft seal surface, thus the main shaft can be protected from damage due to friction while the shaft sleeve if damaged can be replaced easily.
- Turbine Guide Bearing.
Located on top of the head cover and the bearing housing is bolted to the head cover, it is used to take or hold any radial load imposed on the runner and also protect the runner from touching the wear ring while rotating.
This bearing is attached to a temperature detector, an oil level detector and an oil water contamination detector.
- Gate operating Ring.
Turbine guide bearing housing apart from supporting it also has a bearing surface for the gate operating ring.
The gate operating ring is a large ring surrounding the main shaft and turbine bearing, which is used to transfer power from the main servomotor to the movement of the wicket gates.
- Gate Links and Lever.
Movement of the gate operating ring is routed to the gate lever by gate links. This lever is locked at the top of the gate shaft so that when the gate operating ring moves, the gate shaft will rotate. At the connection between the gate links and the lever there is an eccentric pin for adjustment of the gates so that they can close at the same time.
At the connection between the gates links and the operating ring there is a shear pin so that if there is an object stuck on one of the gates, the pin will break so it will not interfere with the gates and other equipment, the shearpin is attached a switch which will give an alarm signal "W / G Shear Pin Failure ”(33SFF) if the pin is broken.
- Turbine Runner.
The runner is the main controlling part of a turbine, bolted at the lower end of the turbine shaft, has blades of stainless steel as many as 20 pieces, diameter = 2847 mm. The water current that enters the gaps between the wicket gates is what hits the blades of the runner, causing it to spin and due to the rapid change in water pressure that always hits it, this runner, especially the blades, is damaged which is called capitation.
In addition, other factors that cause cavitation are:
- Runner blades level against tail water level.
- The speed of the runer's own rotation.
- Surface smoothness of the blades.
- The head of the turbine.
- Wicket gates opening position.
- Runner Cone.
This is the cover of the bottom of the runner which is bolted to the turbine shaft, the intention is to protect the middle part of the runner against the dangers of cavitation and to guide the flow of water smoothly and smoothly into the draft tube.
- Draft Tube.
Made of iron which is connected to the back end of the stay ring, which means to channel the water flow after turning the turbine runner out to the tail bay. At the back end of the draft tube there is a gap for the entry of stop logs, these stop logs are inserted when the draft tube room is to be dried and also the draft tube has an inspection door just below the runner.
- Water Level.
This tail water level is intended to keep the draft tube space full of low pressure water, thereby reducing cavitation in the runner and also reducing the occurrence of water hammer and rough turbine rotations.
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