LPS SOX Sodium Lamps

[trencheel303]

When SON starts to go bad.

Like Mercury lamps go green as they age, SON has a tendency to turn overly pink as it gets old. This one on the left is getting quite bad, and there's another out of shot that is arguably worse. The one on the right was recently replaced so is a nice, fresh yellow colour. Lumen depreciation is noticeable but not too bad, so there's no real need to relamp until they burst.

 

[Sigurthr]

I think that's why I've mostly seen very pink SONs in person. Most places I've been hardly replace blown bulbs, never mind ones that still light. Beautiful photo btw.

 

[Cyparagon]

...they use sodium lasers for observatory guide stars.

Since lasers are named after their lasing medium, it's not proper to call them sodium lasers. It is a 589nm laser, but it's not sodium. Sodium doesn't lase (at least not in any useful/powerful wavelengths)

 

[Sigurthr]

Since lasers are named after their lasing medium, it's not proper to call them sodium lasers. It is a 589nm laser, but it's not sodium. Sodium doesn't lase (at least not in any useful/powerful wavelengths)

That is quite true, but in observatories they usually refer to the laser as "the sodium guide star system", so that's what I tend to call it. They call it sodium because of the sodium D line and the effect on stellar spectrum readings sodium ions in the atmosphere has. Not my jargon, theirs. =)

 

[trencheel303]

Got my merc and sodium ballasts in today, as well as some PF caps.

Interestingly neither ballast cares about the PF caps as they don't even include them on the diagram and the power factor for both is down at 0.45, so they obviously don't even care about PF correction in the specifications.

Fired them up, wasn't sure what was going on at first because the sodium bulb (internal ignitor like the mercury) took about half a minute to start and was just slowly flickering. I guess it maybe takes a few tries to charge the starter and get it going.

You can easily see the merc's arc tube when warming up, and when warm it gives off a brilliant ice white light, it's very well colour corrected. If it weren't for the ever so slight green cast on objects it lights, I'd say it were just a pure brilliant white light.

The merc ballast will light a 50 or 80W bulb, which I thought is quite cool.

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ALSO
redid the wiring for my thorn leak ballast and put a PF cap on. Makes no difference to the noise, so I guess it's just due to age. I assume I've connected the cap correctly:

 

[Blarg King]

Just a quick question about LPS lights.

Do they work in temperatures below freezing? I want to get one to light up my backyard but I'm in Canada and it gets down to minus 30 C here in the winter.

 

[Sigurthr]

Just a quick question about LPS lights.

Do they work in temperatures below freezing? I want to get one to light up my backyard but I'm in Canada and it gets down to minus 30 C here in the winter.

It regularly hits -40F in the dead of winter here, and I've had the 35W LPS SOX fire up every time without fail. Just make sure you're not underdriving the tube.

 

[Blarg King]

Ah excellent. And you can just use a Fullham Workhorse fluorescent driver with a LPS right?
(getting my hands on a genuine LPS driver might be difficult).

Found an excellent online store in Canada that sells LPS bulbs from 18 to 150 watts. I think its only 60$ for a 150 watt too.

 

[Sigurthr]

Yup, Fullham Workhorses work great. Just gotta match the output currents as close as you can, which are listed right on the front covers of the ballasts.

 

[trencheel303]

Does the same store not sell the matching ballasts and/or igniter?

If I'm not mistaken the Fulham line are electronic ballasts that operate at high frequency, much higher than the magnetic lump like my thorn ballast above. The only thing to watch with this is apparently the high frequency doesn't heat the electrodes in the same way the lower frequency (and hence longer pulse) does, thus driving the lamp differently to how a regular magnetic ballast would. My knowledge of electronics is quite basic so I'm only repeating what I've read elsewhere. Just watch for premature blackening of the electrodes and sputter. In practice, it probably doesn't make much difference, but where possible I'd go for the intended parts.

Also, don't run one tip down vertically if you get a larger lamp. The sodium will migrate to the ends (as it tends to naturally) but may eventually gather there and not run the lamp properly. And never run them cap down as the sodium can sink to the bottom where the electrodes are.

 

[Sigurthr]

I wouldn't worry about any electrode sputtering issues on the electronic ballast. Truth is, when running these tubes on said 30KHz ballasts they will still run even if the electrode were to fail. In fact, the 18W tube I just got had some blackening around the electrodes when I first bought it, but after about a day of running on the fulham ballast the tube is crystal clear. HF AC current causes a scrubbing action on oxide laden metals. Also, the electrodes spend less time (consecutively, not in total) without power applied to them, and it is generally during these long unpowered gaps that they cool down, leading to sputtering when power is reapplied. Since they aren't given a chance to cool down they shouldn't sputter as much.

 

[Blarg King]

The store sells high pressure sodium ballasts...they look a lot more bulky and complex than fluorescent ballasts.

 

[trencheel303]

HPS ballast isn't going to work well for LPS, so best stick to the Fulham if you can't get a SOX ballast. The Fulham can also supply a good enough start pulse to ignite the lamp as well so you won't need a separate igniter.

Lamps like these prefer longer run times rather than lots of short start and stop cycles.

 

[Blarg King]

Just a bit of confusion now. All the fluorescent ballasts I'm looking at have 3 output wires, 2 red and 1 yellow...How would I connect that to a LPS bulb?

 

[trencheel303]

What's the make and model or even better the wiring diagram?

I suspect this is more sigurthr's territory than mine.

 

[DashApple]

Just a quick question about LPS lights.

Do they work in temperatures below freezing? I want to get one to light up my backyard but I'm in Canada and it gets down to minus 30 C here in the winter.

As long as the lamp has its outer shell and driver at rated power then they can handle very low temperatures .

The lamp itself without the outer shell would never work as the temperature can never rise enough to fully vaporise the sodium that's the reason the outer shell is coated with indium tin oxide the reflect the IR/heat back to the discharge tube to maintain the temperature needed .