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San Jose LED Streetlamps

We could probably agree to split the difference. In practice I guess it is somewhere in between these two bounds. Either way it is close enough to monochromatic by any reasonable definition.

I did a quick back of the envelope sum using NIST data and reckon there are about 5 visible groups of lines in the sodium streetlamp spectrum that are around 0.5% of peak each plus the red lines from the start gas.

He doesn't have enough horizontal resolution in wavelength to show the gap, but I think both D lines are plotted adjacent with the 2:1 ratio visible. It is still quite a fun educational page. A log/lin switch would be nice.

I dunno about that. With the sodium line saturated I get very visible colour for the green line at ~567nm, weak colour for the blue doublets and also some red lines from the initial cold strike gas.

We are in complete agreement on this point. Worst case using my pessimistic estimate 95% pure and if you are right better than 99%.

Regards, Martin Brown

Reply to
Martin Brown
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Pittsburgh is also doing it..

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Reply to
GregS

And yet again they compare the savings to be made with some insanely geriatric magnetic ballast included against the bare LED fixture.

This is "Green" energy economics of the strangest sort. I noticed the following claims:

}2) Green - Environmental } A 200W LED light only uses 93W of power. However, the existing } 150W High Power Sodium (HPS) bulbs use approximately 230W } (includes the ballast) of power.

This seems to be more than a bit on the high side. The worst performing SON ballast I could spot in a quick search was 185W for a 150W lamp, and there are some others around 165W.

I wish the LED manufacturers would stick to real power = V.A rather than these fake "peak music power" measures. Nonsense statements like:

"A 200W LED light only uses 93W."

Then it is a 93W LED unit with about the same lumens per watt as an HPS lamp but slightly better colour rendition.

The maintenance savings are real, but the energy savings could well be illusory unless the lamps really do have horribly inefficient antique ballasts. And you do have to ask the question why the ballasts were not kept upto date when the energy savings from a swap out

Regards, Martin Brown

Reply to
Martin Brown

I can say that most of Philadelphia's streets are illuminated by 150 watt mercury-retrofit HPS lamps since a change-out from 175 watt high pressure mercury vapor in the mid 1970's. These lamps have been using

240 volt "reactor" type H39 ballasts with loss around 15 watts at least since the early 1970's, probably at least since the late 1960's.

Not far behind 150W mercury retrofit HPS are 400W HPS and 360 watt mercury retrofit HPS, with 240V reactor ballasts having loss less than

10%.

This I know in part from going to the same church as the city's Chief Engineer of Streetlighting back then.

- Don Klipstein ( snipped-for-privacy@misty.com)

Reply to
Don Klipstein

Flyback regulators can operate off anything from a couple of volts to hundreds of volts. The power filtering capacitance becomes extremely small, even in the range of a foil capacitor. You don't get a perfect power factor out of this but it's drawing power from all but the lowest few volts of the cycle.

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I won't see Google Groups replies because I must filter them as spam
Reply to
Kevin McMurtrie

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