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AC vs. DC #37099 04/21/04 03:54 PM
Joined: Apr 2004
Posts: 2
J
jerrytyler Offline OP
Junior Member
Hi y'all. I've really enjoyed reading the stuff on this site, and now I have a question.
I am a lighting distributor, and we sell quite a bit of low voltage lighting. Most of the transformers that come with the fixtures are AC, but certain systems come with DC transformers, and I can't seem to get a straight answer about why, or what the difference would be. The only clue I have is that the DC transformers come with these cable lighting systems you might have seen, so I think this may be a voltage drop issue?

Thanks for any help!

Jerry

Work Gear for Electricians and the Trades
Re: AC vs. DC #37100 04/22/04 07:21 AM
Joined: Sep 2002
Posts: 1,497
C
C-H Offline
Member
Modern electronic transformers (switching mode power supply) output high frequency AC. This means that long cables will cause radio/TV/etc. interference.

Adding a rectifier circuit means greater cost to the manufacturer, lower efficiency and less power.

Re: AC vs. DC #37101 04/22/04 09:25 AM
Joined: Oct 2000
Posts: 2,721
Scott35 Offline
Broom Pusher and
Member
The Low Voltage Incandescent Lamps "May" run a little better using DC instead of AC (well filtered DC as opposed to AC), but the most apparent reason would be to drive LED type Lamp arrays.

Wish I had a definite answer for you, but not knowing the specifics per installation / usage / equipment types, I can only "Ass-U-Me" these two things!

[Linked Image] on the 'Ass-U-Me" word usage!!!

Scott35


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Re: AC vs. DC #37102 04/23/04 10:42 PM
Joined: Jan 2004
Posts: 66
C
cpalm1 Offline
Member
some high quality low voltage light fixtures use DC to improve bulb life. incandescent bulbs last longer on filtered DC than AC. this is because filtered DC is a smooth current while AC has a 60 Hz frequency which causes the filiment of the bulb to vibrate. the vibration shortens the bulb's life


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