摘要 |
Apparatus for modifying electric current consumed by an LED array 2, which may replace an incandescent lamp in a traffic light system, makes the LED array compatible with monitoring equipment 24 normally used for detecting failure of an incandescent lamp. The apparatus has a control device 4 connected to a current sensor 5, current limiter 7, current sink 8, light responsive failure detector 9, and circuit breaker 10. The current limiter 7 and sink 8 provide a current profile with a maximum value above a threshold level to assist current sensing. Circuit breaker 10 is opened if failure of the LED array 2 is detected. A further control line enables light level to be varied gradually. |