| 摘要 |
PURPOSE:To obtain a protective relay operable on a 50Hz/60Hz common arithmetic processing circuit, by calculating the products of the squares of sampling data of current and voltage, and so on, by controlling the sampling data so as to remove the components of the second harmonics and sampling time width, and by producing an output at a judging quantity calculating section. CONSTITUTION:Voltage and current data are stored in storing means 3-9. And an operation expression for system protection to be calculated by using these values is obtained. The operation expression is composed of the first and second electric quantities. A power directional component is found from a value obtained by dividing the first electric quantity consisting of a sampling operation expression having the product of the squared amplitude values of the current and voltage as a multiplicand by the second electric quantity. At that time, 4-rule calculating means 10-27 calculates on conditions that the conditional expressions of the first and second electric component is higher than zero, and a judging quantity calculating section 28 produces an output. And this releases the sampling time width from the system frequency. |
