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Re: [TCML] how to work out average current ?



Hi Tim,

I uploaded some images here..

http://www.future-technologies.co.uk/temp/norm.jpg

http://www.future-technologies.co.uk/temp/zoomed.jpg

the norm.jpg shows a few cycles. The large spike up and down is the 50hz frequency.

i also zoomed in to show just the spike with the time period. It peaks to about 1.1A and lasts for about 600uS...20mA could be correct though thought it would be a little higher at 100mA.

thanks,
Chris



----- Original Message ----- From: "Tim Meehan" <btmeehan@xxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Friday, November 16, 2007 4:42 PM
Subject: Re: [TCML] how to work out average current ?


If I understand you correctly, your waveform looks something like this:
(again, awful ascii art - only works with fixed width font)
_
| |
| |________________
The initial spike lasts 10 microseconds, and the spike repeats every 500
microseconds.  In this case, I am assuming that the spike is a rectangle
(which is prehaps reasonable).  Your average current would be
10usec/500usec*1A = 20mA.

Hope I answered your question :)

Tim

On Nov 16, 2007 8:18 AM, Chris Swinson <list@xxxxxxxxxxxxxxxxxxxxxxxxx>
wrote:

Hi all,

If a curent spike peaks to 1A over 500uS then what is the average curent
over that cycle ?  further complicates things as actual spike only lasts
about 10uS then falls in current to zero over the rest of the 500uS
period..

I am working on a DC res-charge circuit so it draws sharp current pulses.
My
NST will be current limited to maybe 100mA (depending on what NST I use)
so
just wondering if the 100mA limit will be enough to charge the smoothing
caps up.

I think it works out at 150mA, at least that seems to be the RMS figure.
150mA may take longer to charge the capacitor though I do not see this as
a
problem.

I was trying to think how to add a current limiter into my simulation
without using a resistor but can't think of a way of doing it. 5,000uS
seems
to be the charge time on 80mA limit via a resistor though it takes a full
second of time to charge the smoothing caps up..

Does these figures sound about right ?

cheers,
Chris

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