U_{k}  calculation of a choke’s voltage drop The voltage drop of a smoothing coil and thus the voltage reduction of the connected load at the output can be determined as following. The inductive or reactive reactance (X_{L}) dof the smoothing choke can be calculated with the inductance of the choke (L) and the mains frquency (f_{mains}):
X_{L} = ω x L = 2Pi x f_{mains} x L
The voltage drop (U_{k}) of the smoothing choke can be calculated with the rated current (I_{N}) and the inductive reactance of the choke (X_{L}) for 1phase smoothing coils: U_{k }= I_{N} x X_{L} for 3phase smoothing coils: U_{k }= I_{N} x X_{L }√3
_{}Example: Calculation of the voltage drop _{(Uk}) of an onephase smoothing coil with an inductance of L = 0,3 mH, a current of I = 100 A and a rated voltage of 230 V at f = 50 Hz:
_{}Reactance: _{XL} = ω x L = 2Pi x 50 Hz x 0,3 mH = 0,094 Ω Voltage drop: U_{k }= I_{N} x X_{L} = 100 A x 0,094 Ω = 9,4 V or given as percentage to mains voltage: U_{k%} = U_{k} / U_{mains} = 9,4 / 230 = 4%
In an american net with U = 110 V and f = 60 Hz the choke acts as following: Reactance: X_{L} = ω x L = 2Pi x 60 Hz x 0,3 mH = 0,113 Ω Voltage drop: U_{k }= I_{N} x X_{L} = 100 A x 0,113 Ω = 11,3 V or given as percentage to mains voltage: U_{k%} = U_{k} / U_{mains} = 11,3 / 110 = 10,2%
This means the same choke will have more than twice the U_{k%, if operated in an american net.}
Tauscher chokes are calculated to have a small U_{k%}. Especially cut cores and cores made of amorphous and nanocrystalline materials have a small U_{k%} and thus low losses and a very good attenuation of harmonics.
