Re: Input power measurement

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 08:10 AM 3/13/2003 -0700, you wrote:
>Original poster: "davep by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><davep-at-quik-dot-com>
>
>
>>I have a couple of standard house style watt-hour meters that
>
>>I purchased just for this application.
>
>         OK.
>
>>The problem is that the dials rotate too slowly to be useful.
>
>         Even the disc?
>         Might need a second observer, with a watch...


or, since you own it and can remove the glass over the top.. paint some 
black stripes on it and count "fractions of a rev" with a optical pickup..




>>Does anyone have any ideas as to how to soup up the dials.
>
>         Bigger Tesla Coil?
>         8)>>
>
>         Fair question, I've not monkeyed with trying to
>         vary the sensitivity.  Dunno if there are calibration
>         adjustments (and: once 'adjusted' the calibration would
>         be Very Suspect.)


One might be able to replace some of the gear train, but it's going to be 
tough to change the basic rotation rate of the metering disk.  In fact, if 
you look at the front of your meter, there is a "revs of the disk to 1 kWh" 
calibration on it.





>         The design is tightly optimized for 'house size'
>         loads, so may bot be Real Adaptable.
>         CONCEPTUALLY, a current transformer could be used
>         to 'fool' the meter's current winding, however it would
>         be a nonstandard device.  Ditto a transformer for the
>         voltage winding...


In fact, this is sort of a standard thing, so you'll see a lot of surplus 
meters around rated for a 5 Amp load current, the intention being that 
you'd hook up a standard 200:5 or 500:5 kind of current transformer to 
it.  Likewise these kinds of meters have a 115V potential winding, designed 
to be hooked up to a, of all things, potential transformer with a 115V output.

I don't know that you could feasibly play around with this in 
reverse.  What's a reasonable burden for a 200:5 current transformer (a few 
watts) measuring a 10 kW load, might be kind of unreasonable for a 1:5 
current transformer measuring a 100 W load.



>         I DO recall that many such are marked '15A', and am
>         told that this DOES NOT mean 15A is max, rather that
>         15A is the current used to calibrate...
>
>         best
>         dwp
>
>...the net of a million lies...
>         Vernor Vinge
>There are Many Web Sites which Say Many Things.
>         -me
>
>