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LOSS FACTORS??
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From: Jim Lux [SMTP:jimlux-at-earthlink-dot-net]
Sent: Monday, February 02, 1998 11:06 AM
To: Tesla List
Subject: Re: LOSS FACTORS??
> ----------
> From: Zuma [SMTP:mwise-at-ns.sosis-dot-com]
> Sent: Saturday, January 31, 1998 10:45 PM
> To: tesla-at-pupman-dot-com
> Subject: LOSS FACTORS??
>
> Could someone please tell me where the loss factors for di-electrics
> come from. How are these figures derived? Are they based density, what?
Typically, loss is measured by putting the dielectric into a transmission
line (a stripline is most common) or into some sort of standard capacitor.
The cap or transmission line is hooked up to an impedance bridge which
allows you to measure the impedance and loss. You do this at various
frequencies to derive the curve. Most dielectrics have a loss that varies
pretty strongly with frequency. Distilled water is probably most notable
for this, having very low loss at very high frequencies, and ver high loss
at DC (it electrolyzes).
The loss is usually stated as a ratio of the resistive/loss component with
respect to the reactive/capacitive component. You'll see it referred to as
the "loss tangent" which is a reference to the phasor diagram of the power
flow in the component. A loss factor of 0.01 means that 1% of the power
going through the component is getting lost as heat. So, you can see that a
loss factor of .000001 is pretty darn good: you're only losing a millionth
of the power.
This is important in a Tesla Coil for two reasons: 1) The power flows
through the cap a bunch of times for each primary gap firing (i.e. it is a
resonant circuit). The less loss, the more gets transferred to the
secondary. 2) That loss in the primary cap shows up as heat, which in turn
causes the cap to fail.
> I would like to know for the specific reason so I can make sense of all
> of this talk of high loss or low loss for different caps!
>
> Chris
>
>