MEASUREMENT AND CALIBRATION SYSTEMS FOR HYDROTURBINE R&D LABORATORY

Abstract

An international level Hydro turbine R & D Laboratory is going to be established at Alternate Hydro Energy Center in IIT-Roorkee. This will be a unique laboratory of its kind in the country. This laboratory is specially being developed for performing necessary model tests to check the performance characteristics of the hydro turbine. For this purpose, a-very precise and accurate measurement system is required so that overall absolute accuracy on the efficiency evaluation of at least 0.25% and repeatability of at least 0.15% can. be. achieved as per the international standard IEC60193. Such a high accuracy level depends on quality of measuring instruments and much more on in-situ calibration of these instruments. The process of comparing the response of an instrument to agree with a standard instrument over the measurement range is called as calibration of that instrument. In addition, the objective of calibration is to determine the deviation between measured -values and corresponding true values (an absolute calibrator is thus a "true value'). A complete instrumentation system is supposed to be designed very carefully considering accuracy level of all instruments. Thus, selection of the instruments and design of calibration system are also playing a major role as a part of the dissertation work. Apart from this, calibration experiments for all major parameters have to be performed on the scaled down prototypes, so that the best-suited method among the different available absolute methods can be determined. Some new calibration techniques have also been experimented and successful ones can be implemented in the actual laboratory setup: Research experiments have been carried out on a volumetric calibration technique, i.e. automatic volumetric calibrator. This concept has been included for the calibration of flow meter. Using wired sensor networking protocol RS--485/MODBUS, a complete automation system has been developed for the volumetric calibrator, which is used for calibration of volumetric measuring tank that is in turn used for calibration of flow meter. Calibration experimentsfor the instruments measuring other major parameters, i.e. head and torque, with best possible arrangements of absolute measurements, have been carried out successfully. Calibration experiments of pressure gauges have been performed using absolute calibrating device dead weight tester and also by highly accurate. digital pressure calibrator/controller. Torque meter calibration experiments have also been performed by electrical generator type dynamometer and designs of the proposed setup for in-situ calibration facilities of both torque and pressure calibrations have been given.