| Cavitation in Hydroturbine as the same as in other hydraulic machinery, presents unwanted consequences. Hydroturbine is the core set of one waterpower station. It's used to cavitating in the course of running. Therefore, the sequent of cavitation is a great threat to the security of a hydroturbine unit. People have tried many conventional methods to monitor the phenomenon, direct ways, such as observation, photographing, and indirect ways, such as measure of the pressure fluctuations, measure of the noise level and so on. But the products are not satisfied. We have not found an efficient way to monitor cavitation.According to the working condition and working mode, we try to develop a data sampling card for hydroturbine cavitation monitoring research. Single channel and narrow-band signal process is not fit for monitoring cavitation. Different types of hydroturbine and working background disturbance causes cavitation signal to fall in different frequency band. The signal components above audio frequency band are optimal for cavitation diagnostics. Thus, it is very important to raise the sampling rate as well as choose an appropriate frequency band. Moreover, multi-channel can give an estimate of cavitation space allocation and minish the influence of backgroud noise. It means that we'll have a great deal of data to deal with. Therefor, a sampling card with high sampling rate, multi-channel and transmission based on network is presented in this paper, which is very instructive for further cavitation research.Development and research work based on on-line monitoring system in this paper is taken as follows: the design and implementation of hardware in the light of the need. A digital signal processor(DSP)TMS320DM642 of USA Texas Instrument(TI) corporation was integrated. Logical design was realized in FPGA. Sampling frequency can easily changed by DDS. After successfully debugged, data sampling system achieves desired aim. It'll be a useful tool for further research. |
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