| 摘要 |
<p>A lighting power monitoring system detects the availability or a normal or abnormal mains supply at a mains input 5 to enable activation of an emergency lighting mode. The system includes a low-pass filter 21 coupled to the mains input 5 for producing a low-pass filtered output 23. A voltage threshold detector 25 may detect when the low-pass filter output exceeds a threshold, such as when an abnormal DC component is present in the mains supply, and generate a status signal "Out" indicative of the normal or abnormal status of the mains input. The status signal can be applied to an electronic controller (15, figure 1) to control a lighting system in an optimised way in dependence upon whether the mains supply is normal or abnormal.</p> |
