Traffic signal bulb operation for enhanced life time - has bulb of specific rating operated at reduced voltage level to increase operational life by several orders of magnitude

摘要

The operating conditions of filament bulbs specifically for use in traffic light systems are evaluated to achieve an improved operational life. A number of standard filament bulbs of 40,75,100 and 150 Watts is represented by specific current versus colour temps. and are compared with 70 and 40 watt bulbs normally used in traffic light systems. The characteristics indicate considerable improvements in operational life when the voltage is reduced. Typically, a double filament bulb of 150 Watts operated at an average of 155 volts may achieve a life of 100,000 hours compared with only 1000 hrs in the normal range of 220 to 230 volts.