| 摘要 |
<p>PROBLEM TO BE SOLVED: To enhance safety without any flow of an overcurrent in the case where excessively numerous luminaires are connected by providing an overcurrent control circuit for detecting an overcurrent so as not to light the luminaires. SOLUTION: A power source of a control unit for exterior illumination is turned on. If an exterior illuminance detected by an illuminance sensor 2 is a set value or higher, no luminaire 1 is lighted. If the illuminance detected by the illuminance sensor 2 is the set value or lower, a timer 7 judges a time. If it is a lights-out time, no luminaire 1 is lighted; meanwhile, it is a lights-on time, an overcurrent detection circuit 3 judges a current. If no overcurrent is detected, each of the luminaires 1 is lighted. In contrast, if the overcurrent is detected, a signal is sent to an overcurrent control circuit 4, by which an output voltage of the control unit for exterior illuminance is reduced to zero, so that no luminaire 1 is lighted and an alarm display lamp 5 is lighted.</p> |
