Re: Meter Shunts ??

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Black Moon" <black_moons@xxxxxxxxxxx>

Alternately, you can get a *free* DC/AC hall sensor current sensor sample 
(more will have to be bought at about $20~30 each for most) from 
http://www.tamuracorp.com/index.php?src=forms&id=Request_a_Sample

http://www.tamuracorp.com/index.php?submenu=products&src=gendocs&link=Products&category=Main&PHPSESSID=2f30b4156fa05f78b37604876b7a279b 
shows there open and closed loop hall sensors and current sense 
transformers (those only work for ac tho)
Closed loop are more expensive, but more linear and faster (up to 300khz 
responce from the ones I looked at) Models up to 500amps. They also isolate 
the reading from the thing being messured, and usally just fit over your 
wire to sense current. (Some are designed with the wire molded into it 
however) However most need +5v (or some voltage supply anyway) and arnt 
allways output in refrence to ground (Hence how they messure AC) Still, if 
you can get one free, its worth a shot.

> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Re: Meter Shunts ??
> Date: Mon, 14 Feb 2005 18:49:16 -0700
>
> Original poster: Thomas DeGregorio <tommacs@xxxxxxxxxxxxx>
>
>         Oh I'm talking about voltages anywhere from zero volts to 350VDC. 
> Then current anywhere from 0 to oh say about 500amps.
>         Then of course I would like to do primary measuring so then 
> 15KVAC but that's a different story.
>
>         I just wanna to know if using resistors is an efficient way of 
> dropping the current and voltage since it will be to high for the meter 
> to handle. I have found a nice cheap 200 amp panel meter, I so can just 
> use a resistor so it can handle more current and drop the voltage, then 
> just recalculate that new ratio and then I know what the current is. Then 
> do the same with a voltage panel meter though I will need to get one that 
> reads like mVDC since I will need a big meaty resistor.
>
>
> On Feb 14, 2005, at 9:25 AM, Tesla list wrote:
>
> > Original poster: robert heidlebaugh <rheidlebaugh@xxxxxxxxxxxxxx>
> >
> > An additional comment, In old radio transmitters the current meter was
> > mounted recessed behind the front panel a inch or so to protect finger
> > meter readers from high voltage as the meter was at high voltage potential.
> >       Robert   H
> > --
> >
> >
> > > From: "Tesla list" <tesla@xxxxxxxxxx>
> > > Date: Sun, 13 Feb 2005 19:51:56 -0700
> > > To: tesla@xxxxxxxxxx
> > > Subject: Re: Meter Shunts ??
> > > Resent-From: tesla@xxxxxxxxxx
> > > Resent-Date: Sun, 13 Feb 2005 19:52:24 -0700 (MST)
> > >
> > > Original poster: Ed Phillips <evp@xxxxxxxxxxx>
> > >
> > > "A shunt is nothing more than a low value resistor. Current through the
> > > shunt
> > > causes a voltage drop across it such that V = I x R.
> > >
> > > Stephen A. Mathieson"
> > >
> > > It's quite a little more than that.  Most importantly, its a 4-terminal
> > > resistor!  Heavy current flows through the main terminals while the
> > > meter is connected to a second pair of terminals.  That way contact
> > > resistance is minimized and any connection resistance in the
> > > high-current circuit has no effect on the reading.
> > >
> > > Ed
> > >
> > >