Method of predicting the useful life of ultraviolet lamps in electrotechnical systems under UV radiation

The results of predicting the useful service life of low-pressure ultraviolet discharge lamps based on the decline of radiant flux during tests up to 2500-3000 hours are presented in the paper. An assessment of their service life was carried out by extrapolating the values of the radiant flux conservation factor until the moment when this factor in 50% of the lamps decreases to 70% of the initial value. The ultraviolet flux was measured using a radiometer for ultraviolet radiant energy after 100 hours, 500 hours, and then every 500 hours up to 6000 hours. Testing of low-pressure discharge lamps was conducted at a supply voltage of 220V, with a mode of 8 switchings per day for 15 minutes each. The empirical curve for the radiant flux conservation factor was chosen by finding the initial constant and the rate of change of radiant flux using the least squares method. The useful service life for the investigated lamps, with a decrease in radiant flux to 70% of the initial value, was estimated at 8.25 thousand hours and correspondingly, for 80%, it was 4.6 thousand hours.