A sustainable future in terms of energy must involve a reduction in CO2 emissions and our dependence on fossil fuels, which at present satisfy most of the world’s energy needs. Hydro energy delivers both of these benefits, besides it has low operating costs, it requires limited maintenance and is renewable. In coming decades there will be significant growth in hydro energy compared to traditional thermal power plants.

Tailor made generators

 Ansaldo Energia began working in the field of Power Generation with the installation of the first hydroelectric plants at the start of the last century. Since the second half of last century more than 500 hydrogenerators have been designed, built, installed and started up in about 30 countries. Most of all hydrogenerators ever manufactured by Ansaldo Energia are still in operation.
By drawing on experience gained over more than a century in this business, combined with constant product improvement, we can now offer our Clients a comprehensive range of hydrogenerators, in conjunction with after sales assistance services that maximise the investment made in plant construction.
Ansaldo Energia currently produces three basic types of hydrogenerators:

  •  generators for river flow (low/medium speed)
  • generators for high-head plants (medium/high speed)
  • motor-generators for pumped storage systems


Generator design features 


With our “Tailor made” approach for hydrogenerators,  we have always preferred to design generators based on plant characteristics in order to guarantee maximum performance in terms of efficiency, reliability and maintenance.
The process of optimising the hydrogenerator, based on the features of the plant, begins with electromagnetic design to define
the active parts of the machine.

Design data (power output, voltage, speed, etc.) is used to identify the ideal machine configuration based on existing benchmark models, by balancing maximum performance with transport and erection constraints.
The generator project is then verified using advancedcomputational tools to analyse its electromagnetical, mechanical and thermal behaviour.
The heart of the generator is the stator winding and the quality of stator bar insulation is a decisive factor for machine reliability. The new 4657 Resin Rich insulation system, which is derived from our turbogenerators, has made it possible to double the thermal conductivity of the insulation compared with the previous generation and, other conditions being equal, to lower the thermal level of the stator bar, which is beneficial to the lifespan and reliability of the generator.
Our generators are designed with a redundant, closed-circuit cooling system. Based on the type of generator involved, axial fans with adjustable angle blades are used, or solutions with radial ventilation or electric fans for motor-generators which rotate in both directions.
In the case of vertical hydrogenerators for very high vertical load (i.e. for Kaplan Turbine), we can provide proven solutions with hydrulically equalised thrust bearings and, if required, a self-pumping thrust collar.
These solutions are available in non driving end (NDE) thrust bearing configuration with a singlepiece thrust collar, and in driving end (DE) thrust bearing configuration with a two pieces thrust collar.
Generators are designed to withstand the heaviest duty operating conditions, frequent start-up and shut-down cycles, and accidental operating conditions such as short circuits.  An advanced quality system covering all phases of work, from design to start-up, ensures that generators comply with internal and international benchmark quality standards.
Ansaldo Energia has two centrifugation facilities, one of which under vacuum, to balance and overspeed test the generator fly wheel effect up to over 6,000 tm2 and rotor weight over 400 tons. All tests are performed in compliance with IEEE and IEC standards.
Our comprehensive, reliable, after-sales service is reviewed regularly to capitalise on operating experience. 

Product-oriented R&D guarantees constant, gradual evolution in line with Client needs.

Generator test and Inspection

 The inspection and maintenance programmes developed by Ansaldo Energia for power plants, from continuous online assessment to major inspections, are also available for the Hydro Generator line.
Ansaldo Energia has the organisational capabilities to perform all the electrical and mechanical tests needed to verify generator conditions on site, providing the Clients with a report on the tatus of the machine that allows to estimate its ife cycle and to plan maintenance work.
The diagnostic instruments available include he loop test (EL CID) stator core inter laminar ault test system, high voltage winding tests, design veifications with Bump Tests and vibration measurement campaigns, the full range of Non destructive tests (NDTs), and alignment checks and dimensional checks with the help of digital contact-free instruments.

Generator refurbishment, reconditioningand repowering

More than a hundred years’ experience in building generators, combined with the use of advanced reverse engineering tools, allows us to perform refurbishment, reconditioning and repowering work on generators based on any technology.

Main supplies 


In the field of reversible motor-generators units, Ansaldo Energia was already a technological leader in 1938 with the Provvidenza hydro plant (60 MVA, 375 rpm).
Ansaldo Energia’s main high speed generatormotor references are Presenzano (Italy, 3 units, 300 MVA, 428 rpm) and Chiotas (Italy, 4 units, 170 MVA, 600 rpm).
The most important low-speed generators manufactured and designed by Ansaldo Energia are Itaparica (Brazil, 3 units, 290 MVA, 82 rpm), Betania (Colombia, 3 units, 211 MVA, 128 rpm) and El Caracol (Mexico, 3 units, 208 MVA, 128 rpm).
Other important low speed generators, including ITA’ (Brazil, 5 units, 305 MVA, 128 rpm), Salto Caxias (Brazil, 4 units, 345 MVA, 90 rpm) and Machadinho (Brazil, 3 units, 418.5 MVA, 120 rpm), were designed and manufactured on a consortium basis with other companies.


To download Ansaldo Energia Hydrogenerators brochure, click here