| 摘要 |
PURPOSE:To prevent inadvertent energization, by supplementing a power failure time to secure an energization time for a load while an function of energization for a power failure supplement time is refused to be performed when power is restored with the passage of an energization time zone more than twice after a power failure occurs. CONSTITUTION:When power is restored with the passage of two energization time zones after a power failure occurs, a total time of power failure exceeds 24hr plus energization time counted by a power failure energization time counting means 26. Hence, at the second energization time zone, the total time of power failure is counted by a power failure time counting means 25 to clear the power failure time stored 37. When power is restored before the entry of the third energization time zone, the counting contents of the means 26 are cleared and an normal operation is performed. When the restoration of power takes place during the entry of the third energization time zone, the turning on of an output relay 39 is forbidden until the end of the third energization time zone. In this manner, an energization time, for example, 8hr is guaranteed even in case of a power failure. This can secure sufficient energization time to boil up water when an electric water heater is loaded thereby preventing inadvertent energization.
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