| 摘要 |
Invention herewith described refers to a new time-domain digital system for calculation of basic electric values according to the invention represents a new digital system which, using the new algorithm for processing of input analogue values (voltage/current), can perform time-domain numerical calculation of basic electric values as are average values, rms (effective), power or energy of signals being the subjects of processing. Processing is based on a completely new algorithm i.e. on the base of derived analytical expression gives the possibility for on-line calculation, using practically definition formulas for calculation of the specified values, since this is an opportunity to realize an extremely precise instrument which can be used for calibration of less precise instruments. On the basis of integral values of original (analogue) signal the calculation is performed practically by using definition formula for basic electric values. In realization, the use of separate sample and hold circuit is avoided, and the analogue signal directly in circuit for integration is introduced, after that its digital equivalent is formed. High level of synchronization with measured signal is reached by using the simple circuit and counting resources of microprocessor. The device is equipped with serial connection by which it is connected to its master PC, or to a bigger integrated information system. Errors in transmission are detected with CRC (Cyclic Redundancy Check). With suggested device we can process signals in presence of nonharmonic components (interharmonics and subharmonics). The particularly important is the fact that proposed instrument not yet realized in the world and in our country. The price of this instruments will be very cost-effective because of the simplicity of the hardware used for realization. All necessary conditions for specified types of processing, suggested in the digital system according to the herewith described invention, are defined.
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