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Re: Ragowski(sp?) coils



Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi Jim,

	Of course, you have hit on THE solution :-)))  And, there is a simple
trick for getting the current into range.  Just put a 242.4pF cap in series
with my present 24nF primary cap and measure the 1% of the current in that
leg.  That will have 1% of the primary current going though it.  Thus, the
1V/A Hughes current transformer will give 9000 amps peak and 1500ARMS.  It
will give 10 volts at 1000 amps which is just right for the scope input.
They are also metal cased so I can ground the begeebies out of them.

QED ;-)))

Thanks for that tip.  Saves a lot of money and a trophy case for the
Pearson jewel!

Cheers,

	Terry


At 05:46 PM 1/2/2001 -0800, you wrote:
>what about using the current transformers you already have and adding
>another transformer to get the current down into the area where the ones
>you've got will work.  Or a resistive shunt arrangement for 99:1, with the
>current probe on the 99 leg.  The probes you've got have good high frequency
>response, etc., just not the max current you need.
>
>Something like 0.99 ohm and .01 ohm in parallel (or similar)
>
>----- Original Message -----
>From: "Tesla list" <tesla-at-pupman-dot-com>
>To: <tesla-at-pupman-dot-com>
>Sent: Tuesday, January 02, 2001 4:46 PM
>Subject: Re: Ragowski(sp?) coils
>
>
>> Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>
>>
>> Hi Dave, Bert, All,
>>
>> Richard also ended up just getting a current monitor (CT) from Pearson.  I
>am
>> looking at the #4997.  0.5Hz to 20MHz, 150ARMS, 20000A peak, and 0.01A/V.
>It
>> would be perfect for everything I need in this range!  However the $800
>price
>> tag will take some thought $:-|
>>
>> Cheers,
>>
>>         Terry
>>
>>
>> At 07:04 PM 1/2/2001 -0500, you wrote:
>> >
>> > Hi Bert
>> >
>> > Tesla list wrote:
>> >>
>> >> Original poster: "Bert Hickman by way of Terry Fritz
><twftesla-at-uswest-dot-net>"
>> >> <bert.hickman-at-aquila-dot-net>
>> >>
>> >> Hi Dave,
>> >>
>> >> Thanks for providing some more detail - I remember Richard discussing
>> >> this a while back, but this provides more missing info. Did he build
>his
>> >> own integrator with a high slew rate integrator? Calibration for very
>> >> high currents was done via comparison with calculated peak currents for
>> >> high-current discharge with known L and C and attenuators on output? I
>> >> was looking at buying a high current one (100 kA), but the cost was
>> >> almost $1k for the coil and battery powered integrator module, so I
>> >> opted to use a Current Viewing Resistor (CVR) instead...
>> >>
>> >
>> > ---------------------SNIP--------------------------------
>> > Richard likewise used a CVR.  The distributed R idea was published in an
>> > article on RC's in Power Conversion & Intelligent Motion (PCIM) Trade
>> > Magazine about 2-3 years ago.  A flexible RC is made by somebody
>> > (I believe the firm is in the UK), with integral op amp filtering.  The
>unit
>> > was flexible similar to a "clip-on" ammeter, to allow temporary mounting
>> > around bus bars on VSD's, traction drives, etc.
>> >
>> > Good hearing from you Bert!
>> > Regards
>> > Dave Sharpe , TCBOR
>> > Chesterfield, VA. USA
>> >>
>> >>
>> >> Happy New Year to you!
>> >>
>> >> -- Bert --
>> >> --
>> >> Bert Hickman
>> >> Stoneridge Engineering
>> >> Email:    bert.hickman-at-aquila-dot-net
>> >> Web Site: <http://www.teslamania-dot-com>http://www.teslamania-dot-com
>> >>
>> >> <--------SNIP----------------->
>> >
>>
>>
>>
>>
>>
>