Made a Rotary Converter.....I now have 3 phase 415v Mwahaha (Video)

[Tilly819]

Hi all,
The workshop now has 415v three phase courtesy of a 4KW rotary converter. The Lathe is now alive and I have my eyes out looking for a Bridgeport...

Hope you enjoy.

Cheers

 

[Pete.]

That's an excellent video.

Is it the act of running the neutral to the star point that causes the motor to generate 415v? That's a novel approach that I never heard of before.

 

[rtbcomp]

Any chance of the circuit for the one you made? Because we know it works and easier for lazy people like me than trawling the net.

 

[Shox Dr]

Very tidy. I’ve a similar setup, with the addition of a 3ph transfromer. Spitting out 7.5kw Any idea what the transformer is doing/for.

 

[snoozer]

Brilliant skills as much for the design as the end result.

 

[Seadog]

That's an excellent video.

Is it the act of running the neutral to the star point that causes the motor to generate 415v? That's a novel approach that I never heard of before.

Each phase winding in a 415v 3 phase (star) motor will have a nominal 230v across it, so once connected in star you are simulating that condition. You end up with a neutral that is floating above ground which you need to be aware of.

 

[skotl]

Excellent work!

 

[steviec_lj]

Finally, a video that explains the idea in a nice, easy to follow format. You wouldn’t believe the amount I’ve watched.

Now to collect the parts required, and add it to the list of projects

Would you happen to have a wiring diagram for your design, looks extremely neat and well thought out. Putting it in a trolley is a fantastic idea too

 

[Parm]

Looks really good and well executed. However I don’t understand how it works. Doesn’t the motor need to be driven by another motor ?

 

[Shox Dr]

Looks really good and well executed. However I don’t understand how it works. Doesn’t the motor need to be driven by another motor ?

You are confusing that with a balance motor setup, where a secondary motor is running all the time, I believe it was to smooth out the load

 

[Parm]

You are confusing that with a balance motor setup, where a secondary motor is running all the time, I believe it was to smooth out the load

So, if I’m right. 240 v makes the motor work. Then some electricery happens inside the motor to make 415 3 phase

 

[Pete.]

Looks really good and well executed. However I don’t understand how it works. Doesn’t the motor need to be driven by another motor ?

A 3 phase induction motor will start (and run) on single phase with just a capacitor wired across live and the spare wire of three. You lose a lot of efficiency and the start-up torque is very low but once it's up to speed it'll run well enough. Also, once it reaches it's running speed the fact that it relies on 'induced' currents means that the un-powered leg of the three phases gets a voltage generated on it.

Up-side is that you really can generate 3-phase from single phase very simply. Down-side is they are not terribly efficient and draw a lot of current from the mains.

 

[Tilly819]

Right, that is a lot of questions.... I will answer them all in the morning. Thank you all for your kind words.

 

[Tangledfeet]

Superb! Watched it before I'd seen your post here.

Certainly makes sense if you have several 3ph machines; I've only one so bought an inverter.

Good luck in getting the Bridgeport!

 

[armalites]

@Tilly819

Some nicely made videos, easy to watch and informative

 

[Fazerruss]

Each phase winding in a 415v 3 phase (star) motor will have a nominal 230v across it, so once connected in star you are simulating that condition. You end up with a neutral that is floating above ground which you need to be aware of.

If wired like this when it switches to star mode in theory would the neutral stay grounded? In theory this design is negating the need for a step up auto transformer as the motor sort of does this between 1 and 3.
I would have thought you would need a big idler motor though as you are pulling a lot of current through just one set of motor windings on the 240v supply in.


I'm interested in expert opinions on this as I would like to build one eventually but I want it to be a "safe" design.

There was this fella who said he had done so but hasn't done a third video with an explanation...

 

[WorkshopChris]

How do you adjust capacitance for differing loads/machines ?

 

[WorkshopChris]

I would have thought you would need a big idler motor though as you are pulling a lot of current through just one set of motor windings on the 240v supply in.

Thats what i am trying to get my head around, spent 20 years around various phase converters. Supply looks very light gauge cable on the 16 amp plug, i would expect big volt drop on start ups.

 

[Fazerruss]

How do you adjust capacitance for differing loads/machines ?

I think the ready built rotary phase converters from Transwave ect don't need the capacitors changing as they are matched to the idler motor only which is constant.

 

[Fazerruss]

Thats what i am trying to get my head around, spent 20 years around various phase converters. Supply looks very light gauge cable on the 16 amp plug, i would expect big volt drop on start ups.

I also would expect the idler motor to be at least 3 times the size of the total load put on it.