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SIME Energia s.r.l. (Ascoli Piceno- ITALY) has recently set up a new series of unit- composed systems for hydroelectric generation especially created for the following purposes:

  • high hydraulic efficiency, both mechanical end electrical;
  • cost reduction;
  • smaller dimensions and relative economy in civil works;
  • easy installment and maintenance


Such results have been achieved with the use of fast Francis rotor reaction turbines, directly coupled to electrical generators, both of synchronous and asinchronous types, forming a single unit rigidly coupled.

For power up to 200 kW the rotation speed is normally 1500 r.p.m. while, for higher power, it is reduced to 1000 or 750 r.p.m. (1200, 900 or 720 r.p.m. for 60 Hz).

The direct coupling of the electrical unit by means of the interposition of a flexible coupling with consequent elimination of bearings and belts, enables the increase of 5- 6 points of the total efficiency of the unit.

The components and the essential characteristics of the units are:

The turbine
It has been devised in such a way not to have lubricated parts in contact with water. This enables the use of the machine also on aqueducts, as the complete absence of polluting substances is guaranteed.

The special construction features make all the parts of the unit accessible (impeller, distributor, pillow block and relative bearings). In this way all the inspection and maintenance operations are very simple.
The maximum working pressures for normal constructions are: 16 Kg/cm2 and, for some sizes, 25 Kg/cm2.
However, special constructions with higher pressures are possible, if required.

 

The electric generator
If the generator is synchronous, it is equipped with a coaxial exciter without brushes (Brushless system) with automatic voltage regulation within ± 1,5%.

It is possible to start, by means of an optional supplementary device, even motors having the same power of the generator.

The windings are impregnated with special varnishes for the working of the machine in tropical climate; the normal voltages are 380/220 Volt ±5%- 60 Hz.

The efficiency ranges from 82% to 94%, according to the dimension of the machine.

If the generator is asynchronous, for running in parallel with the electric network, it is the reduced loss type up to the power of 55 kW (with efficiency ranging from 90% to 94%) and normal loss type for higher powers with efficiencies from 92% to 95,5%.

Regulation
The regulation parts are different, according to the dimensions and the type of the electric machine.

For autonomous running units not in parallel with the electric network and power up to 25/30 kW, they consist of the distributor with swinging guide blades operated by a handwheel for the initial regulation of a system of ballast resistance in parallel with the load and whose electric input is regulated by a static type electronic system without parts subject to wear: the speed is regulated with an accuracy of ± 1 Hz from empty to full load.

For higher power, we advise systems directly operating on the distributor by means of a hydraulic servomotor controlled by an electronic regulator with accuracies very superior to the ones stated above (± 0,3%).

Safety devices
In order to protect low power machines against serious damages the following are provided:thermostats on the turbine and generator bearings, overspeed switch and overload thermomagnetic power switch.
More complex electric safety devices can be provided for higher power units.
All the devices operate on a butterfly valve which, operated by means of the releasing of a counterweight, assures the complete closing of the penstock stopping the turbine.
All the electric equipment and instrumentation are housed in a control board.
The fitting up is very simple, as it is limited to: the connection of the delivery waste pipes; the building of a concrete base of suitable size on which the unit is to be fixed; electric connections.
In the former page there is a diagram showing the available heads.
The possibilities of application of our units, in the field of aqueducts essentially, can be extended by means of the fitting up, in parallel or in series, of two or more turbines for the subdivision of the flow rate or the available head (the green coloured area in fig. 5 represents the range obtained by means of a connection series).
SIME Energia s.r.l. is able to realize plants with different types of turbines too, both in the field of high heads and low flow rates (Pelton) and in the field of low heads and high flow rates (fixed and variable in motion blades propeller, simple or double regulation), besides units for special applications such as turbine- pump group (see fig. 5).
We’ re at your complete disposal for technical advices, estimates and complete studies of plants.