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An even lower power setting
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As it turns out, it's possible to run the Philips HPI-T Plus 250W at an even lower power on a 100W HPS inductor ballast. The lamp wattage stabilizes at 125 W and the light output is still a very respectable 9630 lm, which is 66 % higher than that of a clear mercury lamp of same wattage. The light color is even more saturated than at 185 W on the 150W HPS ballast, and it is clear from the color aspect of the discharge that indium and thallium dominate the plasma's optical output. Most of the sodium iodide dose is condensed at the bottom of the quartz arc tube.
Of course, one cannot repeatedly start a 250 W metal halide lamp on a 100 W ballast and expect the electrodes to be unharmed in the long run. The lower available current results in a very long glow time, during which tungsten sputtering occurs. So, to solve that issue the lamp has to be started with a proper ballasting impedance and power can then be reduced after 5-10 minutes of operation. A very convenient way to achieve that is to use a pair of HPS chokes connected in parallel, a 150 and a 100 W one whose combined impedance is 51.5 Ohm at 230 V, which is practically the impedance value of the 250 W HPS ballast. A further advantage of such combination is that the power of the HPI lamp can then be reduced to either 185 or 127 W depending on which choke is disconnected after the lamp has reached a stable full regime.
This is a very simple method but an effective one which guarantees that the extended service life resulting from the lower burner temperature is actually realized. If run mostly at 125 W, the HPI-T Plus 250W should, in average, then outlast most mercury lamps and still deliver more light overall.
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Search![An even lower power setting
As it turns out, it's possible to run the [url=https://trad-lighting.net/gallery/displayimage.php?pid=1434]Philips HPI-T Plus 250W[/url] at an even lower power on a 100W HPS inductor ballast. The lamp wattage stabilizes at 125 W and the light output is still a very respectable 9630 lm, which is 66 % higher than that of a clear mercury lamp of same wattage. The light color is even more saturated than at 185 W on the 150W HPS ballast, and it is clear from the color aspect of the discharge that indium and thallium dominate the plasma's optical output. Most of the sodium iodide dose is condensed at the bottom of the quartz arc tube.
Of course, one cannot repeatedly start a 250 W metal halide lamp on a 100 W ballast and expect the electrodes to be unharmed in the long run. The lower available current results in a very long glow time, during which tungsten sputtering occurs. So, to solve that issue the lamp has to be started with a proper ballasting impedance and power can then be reduced after 5-10 minutes of operation. A very convenient way to achieve that is to use a pair of HPS chokes connected in parallel, a 150 and a 100 W one whose combined impedance is 51.5 Ohm at 230 V, which is practically the impedance value of the 250 W HPS ballast. A further advantage of such combination is that the power of the HPI lamp can then be reduced to either 185 or 127 W depending on which choke is disconnected after the lamp has reached a stable full regime.
This is a very simple method but an effective one which guarantees that the extended service life resulting from the lower burner temperature is actually realized. If run mostly at 125 W, the HPI-T Plus 250W should, in average, then outlast most mercury lamps and still deliver more light overall.
Keywords: Lamps](albums/userpics/10005/10/normal_DSC_2309m.jpg "Click to view full size image
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An even lower power setting
As it turns out, it's possible to run the [url=https://trad-lighting.net/gallery/displayimage.php?pid=1434]Philips HPI-T Plus 250W[/url] at an even lower power on a 100W HPS inductor ballast. The lamp wattage stabilizes at 125 W and the light output is still a very respectable 9630 lm, which is 66 % higher than that of a clear mercury lamp of same wattage. The light color is even more saturated than at 185 W on the 150W HPS ballast, and it is clear from the color aspect of the discharge that indium and thallium dominate the plasma's optical output. Most of the sodium iodide dose is condensed at the bottom of the quartz arc tube.
Of course, one cannot repeatedly start a 250 W metal halide lamp on a 100 W ballast and expect the electrodes to be unharmed in the long run. The lower available current results in a very long glow time, during which tungsten sputtering occurs. So, to solve that issue the lamp has to be started with a proper ballasting impedance and power can then be reduced after 5-10 minutes of operation. A very convenient way to achieve that is to use a pair of HPS chokes connected in parallel, a 150 and a 100 W one whose combined impedance is 51.5 Ohm at 230 V, which is practically the impedance value of the 250 W HPS ballast. A further advantage of such combination is that the power of the HPI lamp can then be reduced to either 185 or 127 W depending on which choke is disconnected after the lamp has reached a stable full regime.
This is a very simple method but an effective one which guarantees that the extended service life resulting from the lower burner temperature is actually realized. If run mostly at 125 W, the HPI-T Plus 250W should, in average, then outlast most mercury lamps and still deliver more light overall.
Keywords: Lamps")
