RE: [CAD_CAM_EDM_DRO] Re: CNC power supply question

The life referred to at either 2000 hours or 60000 hours is the expected
duration at the rated performance values. In fact, it will last much
longer. What goes away is not the ability to store energy, but rather the
leakage goes up and the voltage breakdown goes down. This is also covered
at the mfg page at http://www.capacitorindustries.com/SEI/guidelines.htm.

The leakage will be unlikely to be a problem since these caps are not worked
very hard. Note this is not the case on the drive. The small electrolytic
caps that are on drives are much more of a problem and are prone to failure.

GTJ

> -----Original Message-----
> From: Tony Jeffree [mailto:tony@...]
> Sent: Tuesday, March 09, 2004 3:31 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Re: CNC power supply question
>
>
> Ken -
>
> The following extract from a spec sheet chosen at random, for a range of
> "long life" screw terminal electrolytics:
>
> Shelf life 2000 h at 0V +85°C, or
> 4 years at 0V +40°C
> Operational life time 60000 h at +85°C
>
> Seems to indicate pretty clearly that the lifetime is severely
> shortened if
> stored at 0V.
>
> Regards,
> Tony
>
>
> At 07:37 09/03/2004, you wrote:
> >Doug:
> >
> >I would be interested in seeing some capacitor manufacturers data on
> >this. Aluminum foil etched electrolytic capacitors like to be fully
> >charged before use or after a long time in storage but I know of none
> >that have a problem with full discharge.
> >
> >The only issue I am aware of is reverse polarity but that can't happen
> >with the supplies we are talking about. Some manufacturers ship
> >capacitors with a shorting strap across them. How can that be possible
> >if they can't be discharged to zero volts.
> >
> >Ken
> >
> >
> >--- In CAD_CAM_EDM_DRO@yahoogroups.com, Doug Fortune <pentam@c...> wrote:
> > > bull2002winkle wrote:
> > > >
> > > > The only thing I have not seen that you may want is a
> bleeder resistor
> > > > across your filter capacitor to discharge it when power is
> turned off.
> > >
> > > Definately not! While bleeding the cap is an ESSENTIAL
> SAFETY thing to
> > > do while building up the (unregulated) power supply (and I provide a
> > > temporary resistor in the kit for that purpose, for working around or
> > > trying to hook up a gecko to a charged capacitor is exceptionally
> >dangerous
> > > to life & limb & Gecko), ... bleeding a big electrolytic down to 0
> >volts
> > > over the long term will lessen its life considerably (from perhaps
> >15-20 years
> > > down to perhaps 3-4 years).... so says the manufacturer of my monster
> > > (68,000uF 80V/100V capacitors).
> > >
> > > In fact, when the capacitors arrive from the factory they all have a
> > > 'storage voltage' on them of 3 to 4 volts.
> > >
> > > When the capacitor is hooked up to my three G201 Geckos, and the PS
> >is powered
> > > OFF, the Geckos drain the capacitor down in about 2 minutes, but
> >ONLY down to
> > > 1.4 volts where I presume the Geckos transistor junction blocks
> >further drainage.
> > >
> > > This is a perfect symbiotic circumstance.... the cap is drained in a
> >short
> > > time for safety, the Gecko's LED goes out to signify the drainage
> >to 1.4V
> > > is complete, but the small 1.4 Volts remains on the cap to
> prolong the
> > > capacitors life.
> > >
> > >
> > > cheers
> > > Doug Fortune watch for -> 2.5KW 70VDC supplies in development
> > > http://www.cncKITS.com (for lathe & mill servo spindles).
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > .
> >
> >
> >
> >Addresses:
> >FAQ: http://www.ktmarketing.com/faq.html
> >FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> >Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
> >
> >Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> >Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> >List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...,
> >timg@...
> >Moderator: pentam@... indigo_red@...
> >davemucha@... [Moderators]
> >URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
> >
> >OFF Topic POSTS: General Machining
> >If you wish to post on unlimited OT subjects
> >goto: aol://5863:126/rec.crafts.metalworking or go thru Google.com to
> >reach it if you have trouble.
> >http://www.metalworking.com/news_servers.html
> >
> >http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
> >sister site to the CCED group, as many of the same members are
> there, for
> >OT subjects, that are not allowed on the CCED list.
> >
> >NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING
> >THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
> >bill
> >List Mom
> >List Owner
> >
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
>
> Regards,
> Tony
>
>
> [Non-text portions of this message have been removed]
>
>
>
> Addresses:
> FAQ: http://www.ktmarketing.com/faq.html
> FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
> Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>
> Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
> List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com,
> wanliker@..., timg@...
> Moderator: pentam@... indigo_red@...
> davemucha@... [Moderators]
> URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>
> OFF Topic POSTS: General Machining
> If you wish to post on unlimited OT subjects goto:
> aol://5863:126/rec.crafts.metalworking or go thru Google.com to
> reach it if you have trouble.
> http://www.metalworking.com/news_servers.html
>
> http://groups.yahoo.com/group/jobshophomeshop I consider this
> to be a sister site to the CCED group, as many of the same
> members are there, for OT subjects, that are not allowed on the CCED list.
>
> NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY
> POSTING THEM. DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO
> EXCEPTIONS........
> bill
> List Mom
> List Owner
>
>
> Yahoo! Groups Links
>
>
>
>
>
>