Carl wrote:
> Unless you take measurements the meter resistance is an unknown. The
> Handbooks and internet both describe the process.
>
It's almost a necessity as many meters have internal shunts and that's
when you end up with those super low calculated external shunt values.
At work we had a number of feed back sensors in SCR control circuits.
The meter shunt on the board was a piece of 14 Nicrome about an inch and
a quarter long. These were fed with some hefty current transformers that
fit over the power leads. The output of these was generally on the
order of 0 to 5 Amps AC. The input from some of the transformer output
leads was in the thousands of amps.
73
Roger (K8RI)
> After that the math works.
>
> Carl
> KM1H
>
>
>
> ----- Original Message -----
> From: "Robert Perdue" <kc0hfl@cox.net>
> To: <Amps@contesting.com>
> Sent: Friday, May 29, 2009 12:50 PM
> Subject: [Amps] Meter shunt
>
>
>
>> I have a Weston 301 meter 0-100 ma scaled meter and wish to make a shunt
>> to
>> use for screen current in my 4-1000 amp. The screen voltage is 300V I
>> have
>> used the formula RS=RM/(IS/IM) Okay here is what I used RM = 3ohms meter
>> resistance IM meter current for full scale =2ma I am thinking I need to
>> shunt 98ma for full scale
>>
>> I am just not sure of my math is this the correct formula and am I using
>> it
>> right? I get .06 ohms
>>
>>
>>
>>
>>
>> Bob
>>
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>>
>
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