Previous in Forum: vfd motor-torque & power characteristics   Next in Forum: why slagging in boiler
Close
Close
Close
13 comments
Rate Comments: Nested
Anonymous Poster

DC flourescent lamp

10/06/2007 5:45 AM

dear sir

can i find 120vDC flourscent lamp 72w

if i fond how and where.

Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.
Guru
United Kingdom - Member - Olde Member!! Engineering Fields - Instrumentation Engineering - New Member

Join Date: Jul 2006
Location: Dunstable, England
Posts: 2821
Good Answers: 45
#1

Re: DC flourescent lamp

10/06/2007 1:52 PM

I've never heard of a dc fluorescent lamp before...

You would have to limit the current by electronic means or by a resistor making it a waste of power.

Also the tube wouldn't last long as the electrodes would get depleted and soon burn out.

72 watts is also one heck of a powerful fluorescent tube!

John.

__________________
A little knowledge is a dangerous thing - Googling is far worse!
Reply
Power-User

Join Date: Apr 2006
Location: Texas, by God! Houston for precision
Posts: 167
Good Answers: 2
#2

Re: DC flourescent lamp

10/06/2007 11:43 PM

Check under Street Lights in any big catalogue (Sweet's Spec book probably can point you at dozens, and I remember seeing them @ grainger). Also, double check your specs, 72 vdc is a common use for highway lighting (though I can't for the liffe of me imagine why), and 120W is also a common enough spec. Don't know if I's care to work with someone who wouldn't spec in a dc/as inverter for major lighting, though. Sounds like you're working for an architect rather than an engineer. I'll pray for you

__________________
If all else fails, read the directions. That's if, and only if.
Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#3

Re: DC flourescent lamp

10/07/2007 9:18 AM

Depending upon the style of starter circuit, you might want to make sure that the starter circuit reverses the connections to the tube on a regular basis as otherwise, one end of the tube will fail very rapidly.

In the RN on DC ships in the 60's, we had someone go round and each compartment had a reversing switch to change the power + & - over each day for that very reason....I am sure that this can be or is done electronically today with very little effort.

I use small 8 watt tubes in my caravan on 12 volt DC with some sort of oscillator circuit, it does not seem to burn out one end first, but the tube's life is only a few years (with only a few months usage!).....good tubes from European manufacturers last longer and give better and more natural light !

__________________
"What others say about you reveals more about them, than it does you." Anon.
Reply
Guru

Join Date: Aug 2007
Posts: 548
#4

Re: DC flourescent lamp

10/07/2007 2:57 PM

i have never heard of dc flourescent lamp , specifications mentioned seems incorrect,

it may be 120V , 72W , or dc to ac converter that is inbuilt as a complete module .

Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#5
In reply to #4

Re: DC flourescent lamp

10/07/2007 6:41 PM

Of course you can run fluorescents with DC, what have you got against it????

Just that in your experience it was not done, does not mean that it cannot be done.....

Believe me, a great many DC ships in this world use(d) it just in this fashion.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Reply
Commentator
Engineering Fields - Automotive Engineering - Race ya there... Engineering Fields - Mechanical Engineering - Take everything apart, and while you're in there... Engineering Fields - Manufacturing Engineering - Metal, Metal, Everywhere. United States - Member - Good ole' USA.

Join Date: Jun 2006
Location: Orlando, FL
Posts: 82
#12
In reply to #5

Re: DC flourescent lamp

10/09/2007 11:54 AM

Sure, you and Edison can take the DC side, I'll go with Tesla on this one :-P

__________________
I reserve the right to be wrong, or of no help what so ever - Del The Cat
Reply Off Topic (Score 5)
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#13
In reply to #12

Re: DC fluorescent lamp

10/09/2007 7:05 PM

Your comment lacks some significant info in order to be fully and correctly understood, but you may be referring to the fact that AC in such cases is easier to understand for some folks, then you are right, it is easier to understand.

...but you can still run fluorescents off DC if you know how!!! The circuit is basically the same as an AC circuit and works in basically the same way. The good point is that you do not get 50 or 60 HZ flicker!! A huge plus point for people with sensitive eyes....

If you think about a DC arc welder, holding the Arc, then you know that you can ionise air or an inert gas with DC, the same goes for fluorescent tubes.....I hope this helps you further.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Reply Off Topic (Score 5)
Guru

Join Date: Sep 2007
Location: Wrong end of the yellow brick road in Oz
Posts: 930
Good Answers: 15
#6
In reply to #4

Re: DC flourescent lamp

10/07/2007 9:05 PM

Think of it this way...

you purchase a Fluro that runs from DC, So you have a fluro lamp that runs from DC, you don't know about the little black (or mine is silver) box inside that does the DC-AC conversion, so your oblivious to how it runs, some think of it as "I don't care how it works, it just does"..

So are the specifications so far incorrect, or they are correct as far as the knowledge of the poster?

__________________
Qn, Whats the differance between a Snake and a Onion? Ans, No one cries when you chop up a Snake
Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#7
In reply to #6

Re: DC fluorescent lamp

10/08/2007 6:17 AM

I would just like to mention that with 220volt DC, there is no need from the point of view of lighting a fluorescent tube to have an oscillator or any "electronics" so to say, but as I mentioned before, you need to change the tube polarity each day to ease the wear on one end of the tube and therefore prolong its life....we had 1000s of them in the RN in the 50s & 60s, especially on 220v DC Aircraft Carriers and older DC ships built (or designed) before NATO took over.....

__________________
"What others say about you reveals more about them, than it does you." Anon.
Reply
Associate

Join Date: Jun 2007
Location: Lexington, Kentucky, USA
Posts: 33
#8

Re: DC flourescent lamp

10/08/2007 2:08 PM

You might want to explore some of the marine "yacht" lighting web sights.

Here is a place to start.

http://www.yachtlights.com/cat--Fluorescent-Fixtures--fluorescents

Mike

__________________
"A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away." Antoine de, Sant-Exupery
Reply
Power-User

Join Date: Jun 2006
Posts: 443
Good Answers: 2
#9

Re: DC flourescent lamp

10/08/2007 2:18 PM

120VDC --- why DC?

Reply
Guru

Join Date: Sep 2007
Location: Wrong end of the yellow brick road in Oz
Posts: 930
Good Answers: 15
#10
In reply to #9

Re: DC flourescent lamp

10/08/2007 7:14 PM

DC is easier to store than AC?

The trains (the last I knew) in Mt Isa Mines were electric, DC, they ran from batteries, and I think it was 120V, I worked for a company (previous to now) that made the linear DC 400A & 600A regulators for each train.

__________________
Qn, Whats the differance between a Snake and a Onion? Ans, No one cries when you chop up a Snake
Reply
Power-User

Join Date: Jun 2006
Posts: 443
Good Answers: 2
#11
In reply to #10

Re: DC fluorescent lamp

10/09/2007 1:31 AM

Ah yes that is true, and there are various, other, applications using similar systems.

--- I was really asking so the guest (original poster) might enlighten us with the application he wishes to use the type of lighting he/she referred to. Maybe there is something better that the guest is not aware of and another member might just give that information.

It is always helpful when related information to the question is available for the folks here to evaluate and determine what help the questioner needs.

For example: So far we have answers related to mine trains, aircraft carriers, street lights, and who knows what will follow --- it should be interesting.

By the way the guest has not submitted another post to clarify his/her needs.

Reply
Reply to Forum Thread 13 comments
Copy to Clipboard

Users who posted comments:

Andy Germany (4); Electroman (1); ktel60 (1); MrRoboto (1); Phoenyx (1); Snaketails (2); user-deleted-5 (2); vikas (1)

Previous in Forum: vfd motor-torque & power characteristics   Next in Forum: why slagging in boiler

Advertisement