Hi there, I'd like to introduce myself.

Z

z_Lighthouses

Guest
Hi Im Jim from England. I work for the Research and Radio Navigation Directorate of the General Lighthouse Authorities of the UK and Ireland. and I specialize in lights RD. Ive been lurking for quite a while especially on the LED thread to get an idea of what you think of the various LEDs currently in production. Right now were testing several different types of LEDs and different configurations for the use in lighthouse optics to replace incandescent and metal halide lamps. I also do field light measurements to verify the range of lighthouses and I test smaller beacons on a 70 meter outdoor light range and an indoor zero length light range for photometry (candela) and spectroscopy. Intensity in candela determines the range of a lighthouse. For example for an effective intensity of 100.000 candela and 10 nautical miles visibility the range of the light is 20 miles.



I hope my knowledge of photometry and spectroscopy will come in useful at some point. Thanks for reading
 

LEDninja

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02-18-2011 07:24 PM #2 andersonEE

Welcome! Sounds like a really cool field. I for one am very interested in hearing about your research.

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02-18-2011 07:55 PM #3 Norm

Looking forward to reading more posts from you
Norm

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02-19-2011 01:01 AM #4 StarHalo

It'd take one heck of an array of LEDs to make a lighthouse beacon; something along the lines of the Data Bank 70 but larger and with different optics. The cost would be orders of magnitude more over an incan/HID.

The bigger question is what you have to offer us in creating a portable light using the lighthouse beacon's bulb - I picture a top-handle unit with a ~15" reflector, Li-Ion pack or marine battery.. I know the beam would be completely different since there's no way to incorporate the giant fresnel lens, but surely a 1+ mile hotspot with a nicely focused reflector would be realistic..

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02-19-2011 01:58 AM #5 Fritz HID

StarHalo said:
It'd take one heck of an array of LEDs to make a lighthouse beacon; something along the lines of the Data Bank 70 but larger and with different optics. The cost would be orders of magnitude more over an incan/HID.

The bigger question is what you have to offer us in creating a portable light using the lighthouse beacon's bulb - I picture a top-handle unit with a ~15" reflector, Li-Ion pack or marine battery.. I know the beam would be completely different since there's no way to incorporate the giant fresnel lens, but surely a 1+ mile hotspot with a nicely focused reflector would be realistic..
well StarHalo, i don't think he's looking for a portable unit, 1st off, 2nd, as fas as LED lighthouse lighting goes... a giant FRESNEL lens may be exactly what is in order for a lighthouse LED design.

lighthouses are not searchlights, they are warning beacons to alert incoming craft to land. therefore they need be seen at distance, blinking in a predetermined freq for ID, at long ranges.
LED MAY work in this application, but the array would be huge, consist of very deep cooling, a lens system would be not necessarily be needed, but would be wise, and the initial cost/replacement cost would be HUGE!
i believe it is possible, but unpractical at this point in technology.
Kwatt HID, small arc xenon are, at this time, your more cost effective solutions.

sorry star, i missread your post. i don't think you'd want to tote a lighthouse lamp around, let alone the optics! lol. but it would kick@ss to have one in our back yards! reminds me of the days when i had an FM radio ANT beacon lamp, 2x 750W inan over/under design, with an over 1.5" thick red glass housing, was over 3' tall and around 15" round. fun toy light the whole backyard in a VERY bright red... and the neighbors on both sides, and the 3 neighbors behind me! lol
Last edited by Fritz HID; 02-19-2011 at 02:04 AM. Reason: missread
quod is said " permissum illic exsisto lux lucis " quod illic eram , quod is eram bonus!

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02-19-2011 11:45 AM #6 idleprocess

As fond as I am of the output, efficiency, and diving cost-per-lumen advances that LED's are making, I have to agree with StarHalo that they're likely not cost-effective for something like a lighthouse beacon at this point.

LED's look be be slowly breaking into the niches in the general lighting field. I see linear florescent tubes being increasingly replaced by permanent LED fixtures in applications where maintenance is a concern (I'm seeing a lot of signage applications where 4' T12/T8 floros are being replaced by LED strips). I don't know how well LED is going to do in replacing incandescents nor compact florescents in the ubiquitous Edison-socket in the US - those fixtures are just a bad situation all-around for LED.

Some automobile manufacturer will probably figure out how to make LED headlights and use their waste heat to keep the lens defrosted in cold climates, then LED may become the new HID for automotive styling.

I don't see LED's winning any time soon in situations where cost-per-lumen, nor where absolute lumen output are the critical factors. T8 floros are probably the most cost-effective way of lighting large indoor office-type areas - they balance initial investment, output, energy cost, and operating cost quite well. The various arc lamps - metal halide, sodium vapor, xenon short-arc - will likely continue to be the leaders in areas where high lumen output are critical.

The accounting that forces lower initial investment price at the expense of longevity and performance hurts LED. Incandescent, florescent, and arc lamps all lower the initial investment cost, but hide the total cost of ownership in ongoing maintenance costs. A well-designed LED fixture should be able to offer similar output while being maintenance-free and lasting for decades without significant maintenance (well-designed, purpose-built residential LED fixtures should reasonably last the life of the structure). Of course, in order to accomplish this, one needs to have assurance that the fixture will indeed last for the purported operating life of its LED's in order to realize the lifetime cost-savings that justify the larger up-front investment.
Last edited by idleprocess; 02-19-2011 at 11:48 AM.
I apologize that this letter is so long; I did not have time to write a short letter

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02-20-2011 08:41 AM #7 Ken_McE

Lighthouses said:
Right now we're testing several different types of LED's and different configurations for the use in lighthouse optics to replace incandescent and metal halide lamps.
What are the most common lamps currently in use? How many lumens are we talking?

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02-21-2011 03:03 AM #8 Lighthouses

In lighthouses we use Metal Halide lamps in rotating Fresnel lenses. In the Lizard Lighthouse for example we use an 1000W Phillips MBI Metal Halide in an 2nd order rotating beacon (Focal lenght 700mm) with a character of flash white 3 sec (Fl W 3s) the flash length being 0.1s. that gives an effective intensity 0f 1,000,000 candela and a range of 26 miles. At Trevose Head in Cornwall where we need only 21 miles we use a 70 watt Phillips CDM-T in a First order rotating beacon (focal length 920 mm) that gives an effective intensity of 100,000 candela. Lighhouses with fixed fresnel lenses we use clusters of Halogen lamps since we need to be able to flash these lamps to generate the character. In Southwold Suffolk we use a cluster of 3 12v 100W GY 6.35 halogen lamps made by BLV in Germany.in a first order lens (focal lenght 920mm) with a character of Fl(4)W 20s (4 white flashes every 20 seconds) that gives 18,000 cd and a 16 mile range. Where we need more range we use a cluster of Osram M33 64657 24v 250w GY6.35 arranged in a cruciform pattern and run at 19.5 VDC this increases the life of the lamp from 200 hrs to over 2000Hrs and we still get 85% of the rated lumen output of the lamp.

In comparison our friends at the US Coast Guard in there lighthouses seem to use only one type of lamp the G.E. 41734 – Q1000T20BP which is a 1000 Watt G38 halogen lamp. From what I've heard GE has quit making these and the replacement isn't as good quality and The Coast Guard is concerned. We use commerical off the shelf lamps which makes our lives much easier.

In addition I have developed a LED prototype we're testing to replace incandescent lamps in fixed lenses using 6 Citizen CL-L233 producing 1335 lm at 720mA and 18.6 Volts I'm running them at 700 mA each and the total power consumption is about 70 watts. By flashing these on a character of less than 1 in 2 (1 sec on 1 sec off for example) i can get away with a fairly small heat sink. However for continuous use a very large heat sink is used. When I figure out how to show photos on here I'll post a picture

Jim
Last edited by Lighthouses; 02-21-2011 at 03:07 AM. Reason: Spelling errors

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02-21-2011 09:58 AM #9 Harold_B

Hello Jim,

Perhaps you could help me out a little. I have the Citizen in my library and the data sheet is telling me that it is rated at 900lm at 720mA / 18.6VDC. I can understand how you are getting the low Wattage by pulsing the LED but what about the output? 8000lm at 70W pulsed isn't bad but is it real? 102.5lm/W pulsed vs 67.2lm/W from the data sheet. I could see that if you were pulsing and over-driving it.

Thanks.

Harold

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02-21-2011 10:35 AM #10 Lighthouses

I'm using the Citizen CL-L233-C13N1 rated at 1335 lm at 720mA and 5000K colour temperature. You seem to be using the CL-L233-MC13L1 rated at 900 lm at 720mA and 3000K colour temperature. To lower the colour temperature you have to have more (thicker) yellow phosphor on the led which leds to a lower output.

Jim

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02-21-2011 01:13 PM #11 StarHalo

Lighthouses said:
In the Lizard Lighthouse for example we use an 1000W Phillips MBI Metal Halide
Is it this guy here?

philips1000whpitmetalha.jpg


That's a big mother arc chamber, but in my theoretical portable unit, you could just start the reflector midway up the bulb, like a defocused Maglite.. Totally worth it for the rated 85,000 lumens..

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02-21-2011 01:32 PM #12 Harold_B

Ah, there you go! Thanks. There are plenty of LEDs cranking out 100+lm/W but not many that are doing it over 1000lm regardless of color temp. Can I ask how you are out-coupling the LED? You mention a lens system but it sounds like thats part of the lamp not the LED retro fit.

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02-21-2011 02:20 PM #13 idleprocess

StarHalo Is it this guy here? [IMG said:
http://img88.imageshack.us/img88/6482/philips1000whpitmetalha.jpg[/IMG]

That's a big mother arc chamber, but in my theoretical portable unit, you could just start the reflector midway up the bulb, like a defocused Maglite.. Totally worth it for the rated 85,000 lumens..
One need only work out the trivial details of a portable >1000W capable power source and ballast...

But it does sound entertaining ... probably as bright as those milsurp 3kW short-arc searchlights some folks are snapping up.
I apologize that this letter is so long; I did not have time to write a short letter

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02-21-2011 04:02 PM #14 Lighthouses

Our 1000W Metal Halides look like this

48484267.jpg


These were originally made by Thorn/EMI until they went out of business then we used the Phillips equivalent until Phillips stopped making them and now we get them from Osram/Sylvania. 110000 lm after 50 hours and we change them every 10000 hours.

This is our LED Fixture

48485017.jpg


It uses 6 Citizen CL-L233-C13N1 rated at 1335 lm at 720mA and 5000K colour temperature. I'm driving them at 700mA which gives an output of about 1250lm per led. the total power consumption is 70 watts the die temperature when on continuously is 65 degC, 85 degC is the max recommended to prevent premature aging. the top of the heat sink is 50 degC.

This is a single panel of the First Order Bi Form rotating lens at St. John's County Down Lighthouse, Northern Ireland where we tested it. The design of this lens give a group flash 2 every 7.5 sec (Fl (2) W 7.5s)

48486275.jpg


A bi form is a two tier lens, there are three panels on the lower tier and three panels on the upper tier. Originally both tiers would have been lit with its own lamp. Now the lower tier is the main light while the upper tier is the standby light, which only switches on if the main light fails.

With GPS being the main Aid To Navigation for shipping, lighting has been relegated to being a secondary Aid to Navigation and we're in the process of reducing the range of many lights. Most 20+ mile lights are being reduced in range to 18 miles. At St. John's with the 1000W metal halide the range is 25 miles. With the LED it's 19 miles and with a 70w CDM-T it's 18 miles.

Jim

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02-22-2011 01:05 AM #15 travinc

Wow this is really quiet interesting! Thanks for the pics Jim! There's not too many light houses where I live as the coral reefs prevent big ships coming anywhere near the shore, always been interested in them for some reason though.

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02-22-2011 03:54 AM #16 DM51

A belated welcome to CPF, Lighthouses! You bring a very interesting expertise to the forum, and I'm sure we all look forward to hearing more from you.

This thread is shaping up extremely well - fascinating stuff.
 

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