Re: Coil Efficiency (and true wattmeter)
From: John H. Couture[SMTP:couturejh-at-worldnet.att-dot-net]
Sent: Friday, June 27, 1997 6:57 PM
To: Tesla List
Subject: Re: FW: Coil Efficiency (and true wattmeter)
At 04:58 AM 6/26/97 +0000, you wrote:
>From: richard hull[SMTP:rhull-at-richmond.infi-dot-net]
>Sent: Wednesday, June 25, 1997 6:20 PM
>To: Tesla List
>Subject: Re: Coil Efficiency (and true wattmeter)
>>I agree. Can you suggest a simple way to measure the capacitor voltage?
>>Regarding wall plug power; who knows how the distorted and pulsed
>>waveforms are affecting our ammeters and wattmeters. To solve the
>>problem, I suggest that we all build the optical isolator wattmeter
>>suggested by Dave Sharpe of the TCBOR. Dave has I believe posted
>>info on the results of the project...and I believe accuracy was within
>>5% which is a lot better than any typical meter, because this optical
>>isolator device gives an accurate representation of the true
>>instantaneous power delivered to the load even with a wandering
>>input voltage and a non-linear, reactive load. The max power input
>>for the circuit is 1300 watts, but maybe this can be "upped" using
>>appropriate shunts. I haven't built one yet, but I don't really think
>>there's any choice, unless someone can suggest something simpler
>>of comparable accuracy.
>>Maybe Dave will add some more info here about his unit.
>Agreed! Dave Sharpe's submitted wattmeter is waveform/power factor
>insensitive and will give absolute true watts consusmed at the plug!
> I measure the capacitor voltage with a capacitive divider system and the
>tank or cap current with a Pearson wideband C.T. Feed one into each channel
>of a DSO scope. Use AXB math function and the resultant wave worm is the
>time ordered instantaneous record of wattage in the tank. It is vastly less
>efficient than anyone would imagine and the losses are huge (make that
>beyond belief (as I have stated many times before on this list.) Wall power
>is just a loss we must live with with current gap switches and other
>materials used by the cloiler. The H2 Thyratron allows good watt efficient
>performance, but is not as robust as the lousiest spark gap and is not
>capable of remaining on for the desired time in lightly coupled systems.
>Also, my work has shown that the instantaneous impulse power in the hottest
>systems is below that calculated by the classic surge impedance equation due
>to the voltage rapidly dropping as the current rises. This indicates
>substantial losses in the switching device and tank circuit components.
>Also in the power tranny, I would imagine.
>Malcolm is right about the loses.
>Richard Hull, TCBOR
Would you give us an example of a coil where you measured the true watts
with Dave Sharpe's wattmeter?
How does the ABX math function work with the record of wattage?