[DML] Re: Headlight switch savers
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[DML] Re: Headlight switch savers



The engineering name for that is "inrush current". The bulb's resistance increases as it heats up reducing the current load. This as opposed to a coil which does the reverse, the load is fairly constant but when the contacts open the current continues to flow and causes arcing across the open contacts. If the contacts are not sized large enough they are pitted and eventually weld together. As I said in a previous post, ratings are very important but you need to understand the load so you can properly spec the correct size relay to handle the load to get a reasonable life expectancy. If you think it is complicated we are only discussing DC currents here, try polyphase AC and it can REALLY get complicated! Especially when you have to consider harmonics.
David Teitelbaum
vin 10757



--- In dmcnews@xxxxxxxxxxxxxxx, Joseph Kuchan <josephkuchan@...> wrote:
>
> 
> By the way, driving an incandescent light with a relay or switch is not as simple as it sounds. A cold filament in a light bulb (i.e. when the bulb is off)  will draw around 10 - 12 times the amount of current it draws when hot, i.e. "on". 
> 
> No joke. The surge current on an incandescent light is more severe than with an inductive load!
> 
> Joe Kuchan
> 
> 
> 
> To: dmcnews@xxxxxxxxxxxxxxx
> From: hmcelraft@...
> Date: Thu, 4 Jun 2009 14:11:32 +0000
> Subje



------------------------------------

To address comments privately to the moderating team, please address:
moderators@xxxxxxxxxxx

For more info on the list, tech articles, cars for sale see www.dmcnews.com

To search the archives or view files, log in at http://groups.yahoo.com/group/dmcnewsYahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/dmcnews/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/dmcnews/join
    (Yahoo! ID required)

<*> To change settings via email:
    mailto:dmcnews-digest@xxxxxxxxxxxxxxx 
    mailto:dmcnews-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    dmcnews-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/



Home Back to the Home of PROJECT VIXEN


Copyright 2006 ProjectVixen.com.  All rights reserved.

Opinions expressed in posts reflect the views of their respective authors.
DMCForum Mailing List Archive  DMCNews Mailing List Archive  DMC-UK Mailing List Archive