Special Instrumentation and Hydraulic Turbine Flow Measurements Using a Pressure-Time Method

The objective of the work was to evaluate the efficiency of a hydraulic turbine by means of the flow measurement, for a given water head. The hydraulic turbine of 180 MW output has been in service for 20 years. The real value of efficiency was needed in order to proceed with minor/mayor modifications to improve it. In a case of a runner deterioration the pressure-time (the Gibson) method was chosen to proceed with a test for flow determination. However, to measure the pressure in the penstock no access from the external space of the penstock was found, so the special instrumentation had to be developed, which could be installed inside different sections of the penstock for determination of the pressure as required by the Gibson method. After the successful installation of the pressure transducers and a special hermetic capsule, from which a cable was laid through the manhole to the control room, the test was carried out at different loads applying the Gibson method. Simultaneously, the instrumentation for the Winter-Kennedy method was installed and calibrated during the test. In the paper all the turbine measured characteristics are given and discussed. It was concluded that the efficiency of the hydraulic turbine was still high and no modifications were necessary. Having instruments calibrated for the Winter-Kennedy method other curves can be obtained at different heads.