[Amps] Meter shunt

Roger sub1 at rogerhalstead.com
Fri May 29 18:13:50 PDT 2009



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 at cox.net>
> To: <Amps at 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
>>
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps 
>>     
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>   


More information about the Amps mailing list