Measurement of energy yield enables checks on compliance with contractually specified losses for new plant.

In addition to this main area of application, measurement of energy yield may also be used to check optimisation of the plant (e.g. ventilation) or identify the performance of an electrical machine by measurement of the yield of a hydraulic engine.


Calorimetric measurement of energy loss is carried out in accordance with internationally recognised IEC and IEEE standards. In order to separately identify sources of losses, it is necessary to measure the flow and heating of the alternator cooling liquid through the following tests:

  • Mechanical heating to identify losses through ventilation and friction
  • No-load heating to identify losses of iron
  • Heating by short circuit to identify losses of copper and additional losses

At the same time, losses from turbines may be identified by measurements in the turbine oil cooling circuits. Additional heating at the nominal operating point will also be carried out on request. The procedures established by HYDRO Exploitation SA for the analysis of yield measurements are standardised and have been validated using measurements from a range of suppliers of alternators.

    Specific skills

    • HYDRO Exploitation SA’s specialists are expert in the installation and use of specific measurement tools, so guaranteeing accurate measurements.
    • Yield measurement should be considered during the cooling system design phase. Our engineers will make their expertise available to you.
    • In addition to on-site calorimetric measurement of losses, HYDRO Exploitation SA’s engineers have specific expertise in the measurement of losses in suppliers’ factories, with prime movers or using measurement by slowing. Contact us to obtain independent expert advice or support for Factory Acceptance Testing (FAT) of your alternators.

    Client benefits

    Owners of hydroelectric plants will benefit from:

    • An unbiased expert, independent of alternator suppliers
    • A team of multi-skilled specialists with experience in renovation, installation, commissioning, diagnostics and maintenance of electric plant.
    • A multidisciplinary partner with expertise in all skills related to hydroelectricity.

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    Rue de l’Industrie 10, 1951 Sion
    HYDRO Exploitation SA
    Rue de l’Industrie 10
    CP 315 - CH-1951 Sion
    Contact us
    HYDRO Exploitation SA
    Rue de l’Industrie 10 CP 750 - CH-1951 Sion +41 (0)27 328 44 11
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