# Re: Current vs voltage in inductive balasting

```Hi Samuel, David,

> Original Poster: "Samuel Rosset" <samr-at-bluewin.ch>
>
> Hello David, all
> > Hello,
> >
> snip...
> >Also, when I
> > used ~20 mH series L, I had a primary line voltage drop of ~25-30V, is
> > this normal? I thought inductive ballasting was supposed to be esentially
> > "lossless", but what causes tha voltage drop? Hope these questions are not
> > to stupid.
>
> That is exactly what I do not understand. I have heard on that list, that
> inductances limit the current without any voltage drop. But in my idea, a
> 20mH inductance will have an impedance of 6.3 ohm (-at-50Hz). So the inductance
> will cause a voltage drop of  Z*I , exactly as a 6.3 ohm resistor would!
> Additionally, an inductance will cause a difference of phase of 90° (+ or -,
> I don't remember, and I am too lazy to open a book now) between voltage and
> current which would influence the power drawn, which is max. when voltage
> and current are in phase...
>
> Thanks to those who will light up my light bulb...

Ohm's law applies to this circuit like any other. The lossless bit is
about the ability of an inductor to store energy. This property is
exactly how they are able to do their job losslessly (if circuit
resistance is zero). It should be remembered that when it comes to
including inductors to "limit current" in capacitor charging circuits
they have created a resonant circuit because of the e-storage ability
of those components. This will be of particular interest to those
tempted to set their spark gaps too wide.

Regards,
Malcolm

```