XPost: sci.electronics.equipment   
   From: CFKinsey@military.org.jp   
      
   On Thu, 18 Jun 2020 23:16:50 +0100, Ralph Mowery    
   wrote:   
      
   > In article , CFKinsey@military.org.jp says...   
   >>   
   >> > If your meter should read, say 1.875 A, the correct reading could   
   >> > be anywhere from 1.872 to 1.878. This is a possible error in the   
   >> > display presented to you in the analog-digital display conversion   
   >> > process. The +/-1.9% possible error is about the measurement   
   >> > taken including - but not only - any error made by the sensor.   
   >> >   
   >> > To put it another way: If the actual current is 1.875 A,   
   >> > inaccuracies in the sensor and associated circuits may process it   
   >> > as somewhere between 1.875 A +/-1.9%. The analog-digital process   
   >> > may introduce a further error of +/- 3 counts in the least   
   >> > significant display digit. Therefore a current of 1.875 A may be   
   >> > displayed as anywhere from 1.836 to 1.913 A.   
   >>   
   >> Thanks, I wonder why all my other meters only list a % error.  Is it   
   included within it somehow, or are they just lying, or do some meters not have   
   this error?   
   >   
   > Most that use a digital meter should know the last digit is not accurate   
   > because of a rounding error.  Say it shows 1.5 volts.  It could be 1.45   
   > to 1.55 or so and still show 1.5.  Some meters such as the one under   
   > discussion is less accurate and can be 3 numbers high or low on the last   
   > digit.  That is why on digital meters you should try to use a range that   
   > shows as many digits as you can.   
      
   Yes, but I was surprised to see up to 7 digits out on this one, depending on   
   the range.  I think DC amps is 3 or 5 dependant on range, and AC amps is 5 or   
   7.   
      
   > -My several hundred dollar Fluke meter shows DC volts to be .05 % +- 1   
   > digit.   
      
   The meters I have are not several hundred dollars, so are you saying they're   
   only +/- 1 digit?  Is the error much higher on the one under discussion   
   because it's a clamp meter?   
      
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