| 摘要 |
PURPOSE:To approximate the watt-hour containing harmonics component with a simple configuration device. CONSTITUTION:A CPU 8 makes a sample hold circuit 7 sample the current and voltage on a power line at one cycle period and time interval T1 of basic wave frequency of 3-phase A.C. current, and the sampled value is transferred to a RAM 12. Then, at the next multiple cycle period, it makes the circuit sample the current and voltage on a power line at time interval T2, and the sampled value is transferred to a RAM 12, and during that process, basic wave and distorted wave watt-hours are calculated based on the sampled value, stored in the RAM 12, which was sampled at the time interval T1. Then, based on the sampling value, stored in the RAM 12, for each time interval T2 extending over the integrating value of voltage and current for the basic wave is obtained, and then multiplied with the ratio between the basic wave and distorted wave watt-hours obtained from the sampled value obtained by sampling with time interval T1, for compensation. |
