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Thorn Rapid Nigrescence Marine Signal

Thorn Rapid Nigrescence Marine Signal

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This high wattage lamp was developed specifically for long-range and high-speed optical signalling during the second world war. Small signal lamps had been used for many decades before this, but sending signals over longer distances requires a more powerful light source - and with incandescent technology this brings the limitation that as the filament becomes larger, its thermal inertia also increases. It takes longer to reach incandescent temperatures and to cool back down to nigrescence, with the result that signalling speeds are limited. The solution came in the form of this hopelessly inefficient 3000-watt lamp, which employs 14 small filaments of low mass in a bulb filled with the thermally conductive gas, helium. The small filaments are able to heat up rapidly, and after switching off, the conductive gas filling cools them more quickly than would be possible with the normal lamp fill gases that are designed to conserve rather than dissipate the heat of the filament.

IN_OS_Auer_OR_30K_115V_stem.jpg IN_WS_Auer_OR_30K_115V.jpg IN_P_Thorn_Rapid_Nigrescence_Signal_3000W.jpg TH_SE_P_GEC_CP22.jpg

Light Information

Light Information

Manufacturer:Thorn Electrical Industries
Model Reference:996-7835
Lamp
Lamp Type:Military Signalling
Filament/Radiator Type:14C-9
Base:P40s
Shape/Finish:GS-170
Service Life:100 hours
Electrical
Wattage:3000
Voltage:210V
Current:14.29A
Optical
Lumen Output:38,000
Lumen Efficacy:12.7 lm/W
Color Rendering Index:100
Physical/Production
Dimensions:170 x 285mm
Factory Location:http://www.lamptech.co.uk/Documents/Factory%20-%20UK%20-%20Leicester.htm
Fabrication Date:1975
Application/Use:High speed marine signalling

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Filename:IN_P_Thorn_Rapid_Nigrescence_Signal_3000W.jpg
Album name:James / Incandescent
Keywords:Lamps
File Size:142 KB
Date added:Mar 31, 2015
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sailormoon_01_uk
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Mar 31, 2015 at 03:57 PM Author: sailormoon_01_uk
HI James, that's a Interesting Lamp, especially with the Filament construction, also it reminds me of my Chinese Made 3000 watt SS & Hole Lamp I have see HERE
rjluna2
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Robert


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Mar 31, 2015 at 06:31 PM Author: rjluna2
Hi James, I noticed there is a grid mesh around the filament. What was the purpose of this?

Pretty, please no more Chinese failure.

James
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Apr 01, 2015 at 02:58 PM Author: James
The grid structure is simply to provide support means to the filaments. Since the filaments are of small diameter they are not very rigid, and require many support wires to keep them in the desired formation. More detailed photos are at http://www.lamptech.co.uk/Spec%20Sheets/IN%20P%20Thorn%20Rapid%20Nigrescence%20Signal%203000W.htm

Your lamp is indeed very similar Colin, which is not so surprising because Thorn used to make those as well. I am surprised that so many Chinese still list these lamps for sale, because even back in the 1970s Thorn replaced these with a special 3kW Halogen Suez Canal lamp.
rjluna2
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Robert


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Apr 01, 2015 at 06:06 PM Author: rjluna2
Your site becomes crystal clear, James

Indeed the grid is actually part of the filament construction!

Pretty, please no more Chinese failure.

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