| 摘要 |
PURPOSE:To obtain anti-time-limit characteristic by a protection output which is sent whenever a specified value is exceeded by a resulting output value following an addition in a fixed cycle to a value obtained through a division by a specified value after a calculation is made based on a digital data computed from AC information of the electric power system. CONSTITUTION:Digital data obtained from an analog-digital conversion of AC information, such as current information of the electric power system is inputted to a operation unit where a current effective value is computed. The result is divided by a specified value DELTAI with a divider 3 to reduce the bit in the processing by an integrator 4 and a comparator 2, and then, the value I/DELTAI is intergrated by an integrator 4. The output is compared with a specified value Ko by a comparator 2. Only when the output of the divider is 0, or 0 successively several times, the integration work is stopped to clear the integrated value. Whenever this integrated value exceeds a specified value Ko, an output is provided in order to protect and control the electric power system. With such arrangement, an anti-time-limit characteristic can be obtained by computation of the effective value with a limited effective value. |
