3x400V Mains Supply Soft Start and Data Monitor

[@tuopeeks]

I am a convert to series capacitors rather than resistors for soft-start after Steve Connor pointed it out to me. They are less likely to start a fire in a load fault condition. 🙂 Might need a longer charge up though.

[@KaizerPowerElectronicsDk]

That is a good point. I do however believe that with a self-holding circuit, with a control power loss, I also cut the mains supply. I can see how the simple setups without this, is a fire hazard.

[@VariacManiac]

That's a neat enclosure. I like pin & sleeve plugs. Makes it nice & portable to carry around.

[@KaizerPowerElectronicsDk]

And we have those CEE plugs everywhere in Denmark. You can literally find a 16A or 32A service everywhere.

[@Alexelectricalengineering]

Nice👍👍😎, I have built a variac PSU that has a self holding contactor circuit that doesn't reenergizes if power is restored, also it has a soft start (time delay is 1S), also having measurement of V,A,W,etc. By the way I also have a power analyzer (MFM376) it has a rs485 interfaces that would be super helpful for logging data but the full featured software is 400€🤑🤑, I think that the software for a expensive instrument should be free (I was buying the instrument new). So sad to hear your variac stack failed 😢.

[@KaizerPowerElectronicsDk]

Most RS485 interfaces are just MODBUS-RTU and with a bit of luck you should be able to find the registers in the manual. Else just start from register 40000 (Function Code 04) and register 0, try and see what you get. Luckily I have other variacs, but my need for large variacs have also changed over time.

[@Alexelectricalengineering]

@@KaizerPowerElectronicsDk Actually I did get the RS485 working, I get a direct Excel spreadsheet out, maybe I should make a video about it. Good to hear your have more variacs.

[@simonward2953]

Nice work Mads i like this :-), dealing with the inrush this way means less equipment coil side i want to go this route eventually for when i build my big stuff 👍

[@KaizerPowerElectronicsDk]

Most of the time, I can do fine with a 16A service, but I make all my equipment rated for 32A. This way I can put multiply coils in daisy chain supply from a single power supply box like this.

[@audibosoundandlight]

Maybe a stupid question but is there any reason we shouldn’t use an inductive ballast instead of resistors for the soft start? I would assume it would be easier to deal with (no heat) but might be missing something. Thanks for the very informative videos!

[@KaizerPowerElectronicsDk]

Just like in a Marx generator, you can use either charging resistors or inductors, the same here. I used resistors as I already had them and I guess they weigh less than inductors :)

[@audibosoundandlight]

@@KaizerPowerElectronicsDk Ah ok cool, a buddy brought me a bunch of ballasts from fluorescent fixtures they ripped out of a building, so it makes a bit more sense in my case I guess. I wondered if the non ideal power factor of the rectifier would be problematic for an inductive ballast, but will give it a try, thanks!

[@douro20]

Does the floppy disk drive work? Surely someone could write some software to parse the data.

[@KaizerPowerElectronicsDk]

Good question, it came with a floppy and that failed to write, but I actually never tried with a new floppy. Or as new as the NOS ones I have are :)