4000 Watt short arc searchlight project

[PolarLi]

Two layers seems like overkill to me, and 1/8 - 5/32 is probably thick enough. High power lights like this either use a single layer of borosilicate or regular tempered glass, and none seems to have any issues with rain, or heavy seas. But there is hundred of different types of glass out there with different resistance to thermal shock. To be 100% sure, I would have ordered a small sample piece of the glass. Measure the light glass with a IR gun. Use a piece of heat resistant tape on the glass to take the readings off (normal IR guns have problems with readings on reflective surfaces) Then heat the sample piece up in a oven to the same temp and sprinkle water on. Increase the temp and repeat. To be comfortable, I would like atleast a 25-50 C reserve. You really don't want the glass to pop in rain. If it does, and water hit the lamp, that goes to, and may take out the reflector...
Now that will ruin your day

:candle:

 

[WDR]

I like your idea of ordering a sample, that's probably what I'l do. And yes, that is my exact concern, I already killed one lamp and at $200 or so each that gets expensive fast, and since I'm buying surplus I'd be lucky to be able to find the same lamp twice. Last time I wasn't so worried about reflector damage, it was cheap and foul tape could have repaired any issues, this one I am much more concerned about possible damage.

 

[Searchlightexpert]

You have to chooose what you are going to obtain with your searchlight. That sets all parameters for which equipment, light source etc, to use. If a pencilbeam is what you want, it is only a Rhodium reflector combined with a Xenon lamp which can provide the best result. If it is more power offered to a larger covered area through a "softer beam" you want, then you must choose a aluminium reflector (with center hole) combined with a large double ended HMI lamp. It is only a matter of what result you would like to obtain.

I have tested both glass, Rhodium and aluminium reflectors for 24" size against HMI 2,5/4 kW as well as Xenon 3-6,5 kW lamps. The longest range was measured at apx. 30 km /1 lux from the 6,5kW Xenon lamp combined with the Rhodium 24" reflector while the most "useful beam" for instance for an icebreaker is obtained from the 4kW HMI lamp since it provide a wider beam before the caracteristic "dark hole" in the middle of the beam occours when using wide beam.

I will see if I can find some pictures from our testbed to add.

 

[Searchlightexpert]

Wrong posting

 

[Searchlightexpert]

Pictures:

 

[Searchlightexpert]

There are only a few manufacturers in the world making such large searchlights for marine applications, and normally they are not visible in their "standard program". They are only being delivered on request to special applications like large icebreakers.

A bit off-topic but I add a few pictures of some very large searchlights the Norwegian searchlight manufacturer Norselight fabricated to some large anchor handling vessels in the 80's. These units were fitted with 4kW HMI lamps.

Some similar searchlights was also delivered by Norselight to two russian icebreakers in the 80's but then with 6,5kW Xenon light source. See picture below. Note the big difference in size compared to the two 2kW halogen searchlight on the bridge wings. These searchlights were really "ultra large" marine searchlights. Performance data was apx. 30 km. range (at 1 lux) when adjusted to narrow beam. Motorfocus was of course supplied as standard.

 

[FRITZHID]

Idk about anyone else but picture links are broken for me.


*scratch, links working now*

 

[medmike]

Idk about anyone else but picture links are broken for me.

I see pics ok....you obviously know Search lights!! Thanks for sharing your knowledge!

 

[WDR]

I see them, another thanks for all the info.

 

[Searchlightexpert]

How is your project proceeding, any progress?

 

[WDR]

Slowly, I'm still considering how I'm mounting the bulb and reflector allowing for focussing.

 

[BVH]

I stand corrected. The Anode of the VSS-3A Tank light lamp is in the Forward position towards the front of the light, not in the rear as posted above.

 

[lightlover]

I stand corrected. ... not ... as posted above.

Wow! BVH,

Must be a l-o-n-g time since you last posted something like that!

Regards!!

 

[BVH]

That's what memory, or loss thereof can do. I look at all these threads as containing good documentation and everyone benefits for accurate information.

 

[lightlover]

BVH,

I can confidently say that: "You've forgotten more than I'll ever know"

I've embarrassed myself by trying to joke ...

My memory has failed me a few times - as life goes on.

YOU - are an expert I admire.

 

[FRITZHID]

BVH is definitely my "go to" short arc guy! Exp is everything.

 

[BVH]

Hey, my head is already too big! Thank you both for the kind words!

 

[WDR]

It's pretty easy to remember things differently then they are, I haven't even been on here very long and I am fully confident in your input BVH.

just want to let you guys know I am currently still progressing on the light. I have redone the ignition system with a noticeable improvement. I am retaining the same ferrite core, but now only using one ignition coil, and have replaced the two bottle capacitors with one small 50kv door knob capacitor. I also rewound the transformer with 9 turns of 2awg XLPE insulated wire and 3 turns of spark plug wire for the primary. This produces a notably brighter and longer spark for ignition. Next I will be working on building the support frame around the reflector. I am pretty close to having all of the mounting plans for the reflector and bulb worked out. I was having some conflicts between accessibility of components and order of assembly. I am maybe unnecessarily adamant on maintaining integrity of the pot and cutting the least amount of holes.

 

[get-lit]

Regarding anode in vs out, the polar intensity is slightly higher toward the cathode, so it's advantageous to have the anode out for long FL reflectors and Anode in for short FL reflectors. But the lamp orientation is more likely dictated by the primary use of the light, as it's generally not as good for the lamp to operate with the anode down. So ground based lights tend to have the anode out and air based lights, anode in. This wouldn't be a concern for marine lights being primarily horizontal operation, so there must be another consideration for the ACR to be anode in. Could simply be that it's more effective to cool in the housing configuration.

EDIT.. Here's more specific info from XBO Technology and Application document... "Tilting the lamp with the anode at the bottom is the worst position. In this case, the convection forces act increasingly against the flow of the xenon gas and the instability of the arc worsens dramatically. Where a fairly large degree of tilt downwards cannot be avoided, it is therefore necessary to consider turning the lamp round in the optical system so that the cathode is at the bottom. Depending on the layout of the optical system, this can sometimes result in a loss of usable light, but it also results in much better lamp behavior."

 

[get-lit]

Interesting note.. until the 70's, Xenon lamps could only be operated in the vertical position. This may be why the original tank light is configured as such.