| 摘要 |
PROBLEM TO BE SOLVED: To provide an electronic watthour meter with inspection function which prevents malicious short-interval inspection. SOLUTION: Counters 11 and 12 count pulse frequency (f) for measuring wathour. At inspection, the output signal of timer device 13 which is supplied through an AND gate 19 clears the content of a register 14 and holds the content of the counter 12. The output signal of the timer device 13 is delayed and inputted in the counter 12, for clearing the counter 12. The output of a timer control device 18 is 1 during the period except for an inspection prohibited period, including a monthly inspection day, while it is 0 as a principle during the inspection prohibited period, for prohibiting inspection. Thus, a malicious short-interval inspection is prevented. |
