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Coil Efficiency




From: 	Malcolm Watts[SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent: 	Sunday, July 27, 1997 2:55 PM
To: 	tesla-at-pupman-dot-com
Subject: 	Coil Efficiency

Hi all,
          It should be plain from the operational scenario I outlined 
earlier that TC efficiency is going to vay considerably depending on 
its loading conditions. You can see the effects of this in the gap 
discharge under different secondary loading conditions. Max efficiency
in terms of throughput is being obtained when the gap reaches minimum 
brightness. In the coupled system this is the point at which Qsec has 
dropped to allow coupling to become critical. From the primary's 
point of view, the resistance reflected into it has become equal to 
its own internal resistance. Since most of the resistance in the 
primary circuit is a non-linear gap resistance, it is clear that a 
non-linear load is required for this condition to be met (i.e. spark).
    Resistance reflected into the primary is dependent on k and 
Qloaded for the secondary. That being so, finding the optimum k for 
the power the coil is running at is required to obtain best output 
(and efficiency). To throw a fly into the ointment, you can achieve 
the same loading conditions at different attached spark lengths. If 
in doubt, get a good oscilloscope and capture the waveforms of a 
normally running secondary.

Another two cents,
Malcolm