Re: [CAD_CAM_EDM_DRO] Re: Why am I still seeing a voltage ?

The meter is so sensitive, it picks up a current flow even without the
other lead connected. Sort of like power lines causing static in your
car radio. No physical connection, but works anyway.

Breaking the common is strange (to me). I know they do that on
switching power supplies. I'm not sure of the reasoning behind that.

Regards,
JJ

On Saturday, Feb 7, 2004, at 21:36 US/Eastern, ja_erickson wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Roy J. Tellason"
> <rtellason@b...> wrote:
>> On Saturday 07 February 2004 05:13 pm, ja_erickson wrote:
>>> Greetings,
>>>
>>> I am in the process of wiring up my controller cabinet and have
>>> decided to incorporate a servo drive e-stop circuit that
>>> was created my Mariss of Gecko Drives. In his circuit he has the
>>> e-stop button disconnecting the "common" side of 110vac. I have
>>> wired the coolant pumps "common" in series with the "common" from
>>> the e-stop button so that if an e-stop condition occurs the
> coolant
>>> pump will shut down. Ater doing this I started the controller and
>>> measured the voltages and when the circuit was complete my
>>> multi-meter showed 117vac, great ,however after I hit the e-stop
>>> switch I decided to mesure the voltage to verify that it was 0 at
>>> the coolant pump, To my surprise it measured 17vac.I am not
>>> accustomed to breaking the "common" leg of a curcuit as my AC
>>> wiring skills are limited to house things.Can anybody tell me why
>>> I still see a voltage?
>>
>> Yes. You don't mention what kind of a meter you're using there,
> but I'd be
>> surprised if it wasn't a fairly modern digital type -- with a real
> high input
>> impedance, typically 10 megohms. Using such a meter, you'll
> find voltages
>> on all sorts of places that you wouldn't expect. Try putting a
> test light
>> across the points you're measuring, even with a smallish
> nightlight bulb or
>> similar, and watch that voltage disappear.
>
> thanks for the reply,
>
> i attempted that feat using a small bulb and it didnt light.
> is there an actual voltage present or are those meters incorrect?
> another interesting thing i noticed is when i break the "hot" leg
> instead of the "common" ,the voltage is 0, kind of like what i
> expect to see.can you tell me why this is?
>
> thanx
> jeff
>
>
>
>
>
>
>
>
> 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
>
>
>
>
>