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This calculator takes values of the magnitude of I1, I2 and I12 (being I1+I2) and resolves it into its common mode (Ic) and differential (Id) components.
Measure:
Note that I_{12} must not be greater than I_{1}+I_{2}, if it is, then the measurements are in error.
The above form allows calculation of I_{c } (the common mode component of current), I_{dc} (the differential mode component of current), θ_{dc} (the magnitude of phase difference of I_{d} wrt I_{c}, θ_{12} (the magnitude of phase difference of I_{2} wrt I_{1}). (The instrument does of course directly read Ic as I_{12}.)
Note that external fields are principally due to 2I_{c} (or measured I_{12}).
The calculator tries to use the number entered, negative numbers will be changed to positive, missing data 0, NaN means Not A Number (correct the input if needed), results will not be calculated when I_{12} > I_{1}+I_{2}.
CMR (common mode reduction) (or CMRR for some) is the the magnitude of the ratio of differential current to common mode current expressed in dB.
The low meter range is the most useful range, as meaningful readings can be made at relatively low power. Keep in mind that Ic=0.1A flowing in each conductor in a common mode choke with an R component of Z (the effective RF resistance of the choke) of say 1000Ω means (2*0.1)^2*1000=40W of dissipation in the choke.
The calculator does not do a lot of error checking, if you enter nonsense, it will probably produce nonsense.
Version  Date  Description 
1.01  30/05/2011  Initial. 
1.02  
1.03  
1.04  
1.05 
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