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Re: Input Power Measurement

Subject:  Re: Input Power Measurement
  Date:  Wed, 28 May 1997 17:09:08 -0600
  From:  "DR.RESONANCE" <DR.RESONANCE-at-next-wave-dot-net>
    To: tesla List" <tesla-at-pupman-dot-com>


To: Bert

If you want to see some real interesting results try running with a
power
factor meter.  You can see the plate current "dip" almost like a ham
radio
transmitter at resonance.  Then as you vary the input current with a
variable inductance you can see the current begin rising again after the
dip.  The dip presents the most efficient area of operation as the
current
actually starts decreasing even though you are increasing the main
variac
power.  At the dip point you are most efficient and this is also
indicated
on the power factor metering as it approaches unity.

As you continue to increase the voltage variac the current again begins
rising.  Point of best spark output for coils in the 6-30 kva range is
about 10-15% up from the dip.  Power useage and current increase
dramatically above this area.  In this area your med to large size coil
will be producing the best and usually the longest sparks.  You can also
actually "hear" this process in the sparkgap and it starts sputtering
and
does not run smooth.

DR.RESONANCE-at-next-wave-dot-net
 

----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-poodle.pupman-dot-com
> Subject: Re: Input Power Measurement
> Date: Tuesday,May 27,1997 7:19 AM
> 
> Subject:       Re: Input Power Measurement
>        Date:   Tue, 27 May 1997 06:20:51 -0700
>        From:   Bert Hickman <bert.hickman-at-aquila-dot-com>
> Organization:  Stoneridge Engineering
>          To:   Tesla List <tesla-at-pupman-dot-com>
>  References:   1
> 
> 
> Tesla List wrote:
> > 
> > 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,
> 
> While precise measurement of input wattage is quite difficult due to the
> non-sinusoidal input currents, the wattmeter should provide a useful
> relative comparison when the systems are run at similar break rates. 
> 
> -- Bert --