Hydro Alternators

The term generating set describes the combination of a prime mover and either an AC alternator or a DC dynamo/generator. In most cases the drive between the two is provide by a direct drive shaft/coupling.

In a Hydro power generator the prime mover is a water driven turbine usually consisting of a vertical turbine and shaft turning an alternator.

The turbine blades are forced around by a combination of water flow and pressure which is controlled by valves on the turbine inlet. The water pressure is provided by the weight of the static height of water above the turbine inlet.

As the energy for the prime mover is free of charge, hydro turbines are normally run at maximum output as a base load station.

A diesel power generator has a diesel engine as the prime mover which is very expensive to run and is normally used as a standby or start up set. The prime mover and the alternator are usually horizontally mounted. Loading is a complex issue as for the benefit of fuel consumption they are best used to supply only the minimum required demand. In terms of life span and service however diesel engines are monitored on ther hourly operation totals.

Therefore by running a diesel at 50% of its output, although fuel may have been saved, it will total up the same amount of service hours as a diesel which has run at full output, which is also regarded as inefficient and wasteful.

The diesel set has to be continually supplied with fuel and requires more frequent and comprehensive servicing, and of course provides air pollution, compared to a hydro set. In theory the alternator can be exactly the same for both prime movers apart from the axis mounting as described, but the hydro power will drive much bigger units.

Usually there is no difference between the alternators used to generate electrical power. A desiel alternator can easily be swaped for the alternator to be driven by a turbine which will convert the hydraulic pressure of water depending on the dynamic head availabe and the volumetric flow rate of water. Your only issue will be obtaining a steady RPM of the output shafts of your turbine which will need a governor to control. These days though electronic load controllers are used to obtain steady electrical outputs from hydro generator (altenators)

One other distinguishing difference between hydro powered alternators and diesel engine driven alternators is the operational speed. Diesel engines like to run at faster speeds than water wheels. To optimize output relative to driving RPM, hydro alternators are wound differently to develop much of their output at lower rotational speeds. Many hydro units turn at a speed below the minimum idling speed of a typical diesel generator.

Elnav

A comment on Low speeds Hydro VS diesel prime movers.

Typically many of the older large vertical Hydro generators had 52 poles and turned at 138.46.. RPM at 60 cycles.

Niagara Falls and Massena used these types.

Westinghouse, Crocker Wheeler, Allis Chalmers, General Electric, Newport News, were among the US manufactures of units those designed for these speeds.

These vertical units were mostly high head Francis turbines.

Kaplan turbines were more like propeller wheels if variable pitch blades so they could take advantage of low head water flows. Allis Chalmers made a number of these.

Pelton turbines were horizontal turbines and ran in the 2 to 3 hundred rpm range. Direct connected alternators worked well but some older machines were belt driven to higher speeds. Pelton wheels were used on small creek flows.

The PASNY Robert Moses plant at Niagara Falls re-built ALL there machines in 2006.

Speed increaser's are finding there way into new designs.

Basically

Well a hydro alternators works on gavailty of water flowing down stream to power a turbine and desiel works on fuel powering the turbine. To put it very simply otherwise we would be here all day explaning.

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Thank you and good night