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Re: Input Power Measurement

Subject:       Re: Input Power Measurement
       Date:   Fri, 30 May 1997 10:54:09 -0700
       From:   Skip Greiner <sgreiner-at-wwnet-dot-com>
Organization:  Greiner, Ltd.
         To:   Tesla List <tesla-at-pupman-dot-com>
 References:   1


Tesla List wrote:
> 
> Subject:  Re: Input Power Measurement
>   Date:  Wed, 28 May 1997 16:46:18 -0400
>   From:  "Thomas McGahee" <tom_mcgahee-at-sigmais-dot-com>
>     To:  "Tesla List" <tesla-at-pupman-dot-com>
> 
> ----------
> > From: Tesla List <tesla-at-pupman-dot-com>
> > To: tesla-at-poodle.pupman-dot-com
> > Subject: Input Power Measurement
> > Date: Tuesday, May 27, 1997 1:46 AM
> >
> > Subject:     Input Power Measurement
> >        Date: Mon, 26 May 1997 23:42:39 -0700
> >        From: Skip Greiner <sgreiner-at-wwnet-dot-com>
> > Organization: Greiner, Ltd.
> >          To:  tesla list <tesla-at-pupman-dot-com>
> >
> >
> > Hi All
> >
> > It is obvious to all that any given transformer can be run in
> excess of
> > its rating. Thus, a 1kva transformer may be run with 2kva input and
> > live. This does not mean that the TC is being run at 1kva since the
> > transformer is rated at 1kva.
> >
> > How can the actual input power to the TC be measured????????
> >
> > We can know the input voltage, I think, since most of us run from
> the
> > mains (except those that insert a variac and transform the mains
> voltage
> > up to 130v or 140v). We can still measure the output voltage of the
> > variac, I think, and therefore know the input voltage.
> >
> > BUT....how can the input current be measured. I seriously doubt
> that it
> > is sinusoidal. There are ac ammeters, several different types which
> give
> > an indication. Is there one type of ammeter, the reading of which
> could
> > be multiplied by the voltage as obtained above, which would give an
> > input power which all of us could use for comparison purposes?
> >
> > I have a commercial instantaneous reading wattmeter. Does it
> provide any
> > usable information? For instance....if I compare the input power to
> two
> > different systems which use different types of input
> > transformers....will I indeed be able to say that one system is
> more
> > efficient than the other?
> >
> > Any suggestions would be appreciated.
> >
> > Skip
> 
> Skip,
> The current can be measured using an RF current meter. Most of these
> use a heavy bar of metal (shunt) attached to a thermocouple. The
> shunt is usually fairly massive. This helps to automatically average
> out the current, and keeps the voltage drop low. This is preferable
> to rectification schemes, as these usually involve an initial voltage
> drop due to the diodes(s) used. You can usually find such RF ammeters
> at those glorious things we call Hamfests. The RF ammeter is not a
> linear device, but it also does not have any "dead" spots. Although
> they were designed specifically for RF current measurement, they in
> fact work just fine all the way down to DC levels.
> 
> Hope this helps.
> Fr. Tom McGahee


Hi Fr. Tom

Great Idea. I never thought they worked down to dc. I always thought
there was a blocking cap involved.

By the way. I am biting the bullet today and will TRY to run the H&R
trannies at high break rates. Hope to report tonight. Also hope that
they live.

Skip