what's a line reactor?

A very enlightening article can be found here:

I have 6 DC power supplies 0-100A, 0-40v, that use saturable reactors/magnetic amplifiers to achieve regulated voltage output.

i

Except that you don't deliberately want a line reactor to saturate and it's not a magnetic amplifier.

There are a couple of things it might be used for. One is between a VFD and a load. A VFD output is a series of steps and since the reactor limits instantaneous current, the steps get smoothed out.

Likewise, since the reactor limits instantaneous current, they are used to keep short-circuit fault current down to a reasonable level until a fuse can blow or a breaker can open.

Line reactors are often used on the line side of VFDs to attenuate electrical noise introduced back into the supply. On the motor side of the VFD a line reactor can protect the motor from voltage spikes caused by long motor leads.

You'd have to track down the part number on yours to tell whether it's intended for either of these uses, or something entirely different.

Ned Simmons

Once the line reactor energizes it works like any choke or coil to oppose a change in current. In essence if the current fed through the reactor drops then the magnetic field collapses a bit adding current to the output. For lower frequencies this works well, for higher frequencies you use capacitors. Back when electronics had the warm glow of thermionic emission the phrase was "pad the low and trim the high" pads being inductors and trimmers capacitors.

Thanks to everyone for the help.

I did a little more digging and found a short summary from Trans Coil that I have included at the end here. It's a PR piece but makes for a good summary.

Would anyone know if the phases affect each other? Do you get the same result if the cores were physically separate?

Does this thing work with single phase?

Tanks, DOC

TCI KLR series three phase AC line reactors are intended for use as input filters for adjustable speed DC drives and as input or output filters for AC-PWM variable frequency drives. Drive performance is significantly improved, the drives input rectifier is protected from failure or damage, and drive harmonic demands are tamed with the addition of a K-rated line reactor. KLR line reactors act as interface buffers between solid state power circuits and the line or the motor. (Not unlike the surge protector for your desk-top PC). All drives, in any application, will benefit when applied with KLR series line reactors.

I hadn't heard it that way - In the stuff I was reading back in those days, the trimmer was a small cap in parallel with the main tuning cap, to set the low-C/high-F point, and the padder was a mongo trimmer in series with it, to set the high-C/low-F point.

But I can see how a padder inductor would work, or maybe tune the loopstick while you're zeroing in...

Thanks! Rich

From the description (which I've left, below), it sounds like an ordinary hash choke or common-mode choke. I remember having seen sketches of the magnetic pathe in a three-phase transformer, albeit I haven't done a thorough

search on it yet - the thing is, on single-phase, you'd get a similar effect by just using one winding, or possibly putting them in parallel, although series might be better - magnetic stuff is black magic to me.

Back to the point, it sounds like you put one winding in series with each phase from the mains, and it keeps the switching noise coming out of your equipment from going back up the mains and screwing up the neighbors' TV. :-)

Good Luck! Rich