San Jose LED Streetlamps

[Martin Brown]

I would say more extreme than that by an order of magnitude, as in
more like 99.5% of visible spectrum content of low pressur sodium
being in one line pair having total bandwidtyh less than 1 nm, and the
next one down probably has less than .2% of the total.

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.

The 2nd-place visible spectrum feature of a low pressure sodium lamp
is close to there, comprised of 4 lines: 567.0, 567.6, 568.2 and 568.8
nm. The first two of those are much stronger than the last two.


I saw that...

The Na entry has only one of the line pairs shown at all, the main one
in the orangish yellow.

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.

This source cites 2nd place being .7%, which sounds a goog half an order
of magnitude high to me if it is a visible spectrum feature. (Likely
according to a spectrometer experiencing saturation or having uncorrected
non-flat spectral response or both.)

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

 

[GregS]

How much government money will PE&G get for changing to white LEDs?

How much government money will PE&G get for swapping out ballasts?

Pittsburgh is also doing it..

http://www.city.pittsburgh.pa.us/district8/assets/pgh_LED_plan.pdf

 

[Martin Brown]

Pittsburgh is also doing it..

http://www.city.pittsburgh.pa.us/district8/assets/pgh_LED_plan.pdf

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

 

[Don Klipstein]

GregS wrote:


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

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 ([email protected])

 

[Kevin McMurtrie]

When they can do 140lm/W at 5-10W they will be competitive as spotlamp
replacements (a position where CFLs are truly dreadful). Pricing is
still an issue even allowing for the longer lifetime.

It depends.
They are currently just fine for spotlamp replacements.
A 50W halogen will put out ~700lm. You can do this with either:
5 LEDs at ~1.1W, for a total power input of around 6.2W (with a 90%
efficient ballast), or two LEDs at ~11W input.
Guess which is going to come to market first.

[snip]

Will/Do those devices include power-factor correction?

No.
At least not on the level of individual fixtures.
It's quite possible to do, of course - but it means another stage.
(or letting the LEDs flicker, which makes them less efficient.

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.