Possible use for large inductor (laminated core)

[RocketScienceSmurf]

I scored two huuge (and heavy - probably around 100kg each) inductors probably made from a regular laminated core. One has a hand written label that says 35mH and the other has a label from manufacturer that says 25mH 50A.

These were bought on an auction so I did not have any chance to inspect before I bought them and since they were in a lot with a couple of 10kVA three phase transformers I had hoped/assumed at least one of them was a three phase choke of some kind but that was not the case.

Can these be used for something fun? Are they only usable in DC applications or can they be used for 50Hz AC as well?

[MRMILSTAR]

If they are made of E and I sections you can delaminate them and make an adjustable air-gap ballast. I made such a ballast for my 6.5 KVA pole transformer powered tesla coil. I used about 80 pounds of laminations and 73 turns of 8 AWG stranded wire for 60 Hz power. 50 Hz would require a little more iron. I can adjust the maximum current in the range of 4 to 40 amps by using various thicknesses of plastic spacers in the air gap between the E and I sections.

[davekni]

Since these already are inductors, they'll have an air gap.  If you want to adjust inductance, then the gap needs adjusting as Steve said (or the winding count changed).  So, you'll need to separate the two "halves" of the core, but likely not need to de-laminate as you would if starting with a transformer.  My guess would be that the existing gap is created by E section(s) having a shorter center leg than outer legs.  That's common in ferrite cores, but I'm not sure about silicon-iron laminations.  If that's the case, then you can add space to lower inductance, but not decrease gap to increase inductance.  Of course, if the existing inductance is close enough, that's the easiest.

Another use of an inductor is between a 3-phase bridge rectifier and the bulk-cap.  Improves power factor (and lowers the DC output voltage a bit, with higher current capability, more than the voltage reduction, so a bit more power) under load.  Just be careful of having too much inductance and the resulting bulk-cap voltage spike when the load is abruptly removed (ie. end of burst of a DRSSTC).

[Mads Barnkob]

Another use of an inductor is between a 3-phase bridge rectifier and the bulk-cap.  Improves power factor (and lowers the DC output voltage a bit, with higher current capability, more than the voltage reduction, so a bit more power) under load.  Just be careful of having too much inductance and the resulting bulk-cap voltage spike when the load is abruptly removed (ie. end of burst of a DRSSTC).

I wrote a small text on passive PFC for DRSSTCs along with a couple of simulations to show the effect of a choke on the AC input.

http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/pfc/

[RocketScienceSmurf]

Thank you all for great input. I will try and take some pictures of the internals and post in a couple of days.

[RocketScienceSmurf]

I took the lid of the smaller one of the chokes and took a couple of pictures yesterday. Is it two "halves" connected in parallell to increase the current rating?

I also started to look into the three phase transformers. I think they can be used as is connected in "Wye" configuration with 230V AC between Live and Neutral. It would be a shame to scrap these for the copper so I would like to find a way to use them instead.