PIT and bulb generators: hydro generators for low-head hydropower plants
Horizontal PIT and bulb hydro generators for low-head run-of-river hydropower plants. PIT generators are typically rated up to 17 MVA at 500–900 rpm, bulb units up to 76.5 MW at heads of 0.5–30 m. Used at small hydropower plants, cascades and in the refurbishment of low-head stations.
- PIT generators
- usually up to 17 MVA, 500–900 rpm, via a speed-increasing gearbox
- Bulb units
- up to 76.5 MW per unit, head 0.5–30 m
- Shaft
- horizontal
- PIT cooling
- including through the pit liner
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
PIT generators and bulb generators are horizontal hydro generators for low-head run-of-river hydropower plants, where the water passes through the unit almost in a straight line. PIT generators are used at small low-head stations and are connected to the horizontal turbine shaft through a speed-increasing gearbox. The higher rotational speed makes the generator more compact and cheaper, so for stations with low heads and small outputs the PIT arrangement is economical, typically up to 17 MVA at 500–900 rpm. The shaft is horizontal, and the generator is coupled to a hydro turbine operating at low head.
The manufacturer stresses a robust design that withstands the high runaway speeds typical of hydropower plants. A special solution offered is cooling of the generator through the pit liner. In bulb units the generator is housed in a watertight casing, the bulb, around which the flow passes.
According to the manufacturer, it is the world leader in bulb units, with an installed capacity of about 6,500 MW and a market share of over 70 %. More than 300 units have been supplied for heads from 0.5 to 30 m, with runner diameters up to 7,700 mm and outputs up to 76.5 MW.
For small hydropower plants, modular bulb and PIT units of the small-hydro series are produced. With a belt drive the output reaches 600 kW at heads up to 5 m, with a bevel gearbox up to 2,600 kW at heads up to 12 m. PIT units go up to 10,000 kW at heads up to 12 m, bulb units up to 15,000 kW at heads up to 15 m. The choice between PIT and bulb design depends on the head and output of the station. For heads of 0.5–30 m and outputs up to 76.5 MW per unit, bulb machines are used, while PIT generators occupy the lower part of this output range, typically up to 17 MVA. The PIT design is built for high runaway speeds, and the bulb unit is placed directly in the water flow.
Applications: run-of-river hydropower plants on lowland rivers, cascades, small hydropower plants, refurbishment of low-head stations.
Technical specifications
| PIT generators | usually up to 17 MVA, 500–900 rpm, via a speed-increasing gearbox |
|---|---|
| Bulb units | up to 76.5 MW per unit, head 0.5–30 m |
| Shaft | horizontal |
| PIT cooling | including through the pit liner |
| Feature | built for high runaway speeds |
Request a price and lead time
PIT and bulb generators: hydro generators for low-head hydropower plants. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
What is the output of PIT generators?
Typically up to 17 MVA at 500–900 rpm with a speed-increasing gearbox. For small hydropower plants, modular PIT units go up to 10,000 kW at heads up to 12 m.
At what heads do bulb units operate?
From 0.5 to 30 m, with an output up to 76.5 MW per unit and a runner diameter up to 7,700 mm. For small hydropower plants, bulb units reach 15,000 kW at heads up to 15 m.
How is a PIT generator cooled?
A special solution offered is cooling through the pit liner. The design is built for high runaway speeds.
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