Rotary Phase Converter (Create 3-phase power from a single phase source)

[old kodger]

junkers2,
I tire of this, either take my word for it or GO AND DO YOUR OWN RESEARCH into three phase motor connections. I'm sure American motors would be the same as Australian motors except for the different potential.
Old Kodger.

[Junker2]

Originally Posted by old kodger
................
................
I'm sure American motors would be the same as Australian motors except for the different potential.

That statement is not real accurate. Most 3 phase motors in the US are 9 lead motors and are convertable between 230 volts (low voltage) or 460 volts (high voltage). See attached diagram for the connection schematic.



Please note these 9 lead motors are fixed at the factory as either a series/parallel wye or a series/parallel delta. Now if the motor is a 12 lead motor we could wire it as series or parallel in a star or delta configuration with multiple voltages (230/400/460). usually the only wye/delta motors in the US are large horse power units designed for wye/delta starting to reduce the inrush starting amps.
If you have access to a 6 lead 3 phase 240 volt delta/415 volt star idler motor you should look at this youtube video:

where "RODALCO2007" starts the motor in delta with single phase 230 volts and swaps it to star to generate 400 volts directy from the 230 volt single phase line, no step up transformer needed. I don't know how much power the idler motor will output when configured this way but it is the most interesting scheme to get 3 phase 415 volts from a single phase 240 V supply without a step up transformer.

[Junker2]

Originally Posted by Frank S

He wouldn't the center tap of the secondaries would be grounded to earth leaving 2 hot wires each having 240 volts or most probably 230v with those he could connect to 2 legs of the 3ph idler motor, and connect his load to all 3 of the legs. A bank of capacitors would help to smooth out the 3 ph out put but not entirely necessary if he has a fractional hp single ph motor to spin up the idler motor.
................
................

To Frank S

If you connect the idler motor as you describe above with 480 volts SINGLE PHASE across two terminals of a three phase star wired motor rated for 415 volts (if wired for three phase delta it would be rated for 240 volts) you will be applying 277 volts across each idler motor winding, not 240 volts!
It appears both "old kodger" and "nhengineer" do not understand how a three phase 240 volt delta/415 volt star motor works much less how to connect one.

[nhengineer]

To Frank S

If you connect the idler motor as you describe above with 480 volts SINGLE PHASE across two terminals of a three phase star wired motor rated for 415 volts (if wired for three phase delta it would be rated for 240 volts) you will be applying 277 volts across each idler motor winding, not 240 volts!
It appears both "old kodger" and "nhengineer" do not understand how a three phase 240 volt delta/415 volt star motor works much less how to connect one.

Yup, that's right. I don't know nothing. How about you Rob?

[old kodger]

Nah!

I've known nothing for about 60 odd years

Rob.

[old kodger]

Mr junkers2,
I apologize for my lack of command of the English language sufficient to communicate to you in post 191 how electric motors are constructed in Australia. So, since words fail......see sketch attached.
However, a reply to this post is not required as I will no longer respond to your comments. I simply refer you to my previous post suggesting that you design and build a rotary phase converter to run on two wire 240 volt single phase.
Regards, Rob.

[Medmike]

Hi Dave.... Sent you pm. I clicked download link too many times. I need it reactivated.
Thanks!

[nhengineer]

Hi Dave.... Sent you pm. I clicked download link too many times. I need it reactivated.
Thanks!

Medmike,

Write to Jon at jon@homemadetools.net and tell him what happened. He'll straighten it out.

[Jon]

All set Medmike - I've reset your download count so you can download the plans a few more times.

[Junker2]

Originally Posted by old kodger

Mr junkers2,
I apologize for my lack of command of the English language sufficient to communicate to you in post 191 how electric motors are constructed in Australia. So, since words fail......see sketch attached.
However, a reply to this post is not required as I will no longer respond to your comments. I simply refer you to my previous post suggesting that you design and build a rotary phase converter to run on two wire 240 volt single phase.
Regards, Rob.

Based on the diagram you uploaded of how you would connect a dual voltage 240/415 volt three phase motor it is obvious you do not have a clue how a 3 phase AC induction motor works, how to wire a 6 lead dual voltage 415 volt star/240 volt delta motor, or the commonly used nomenclature for 3 phase power. The figure on the left of the diagram you uploaded would theoretically work for your imaginary 9 lead 3 phase motor but as wired it would need the utility power to be a 240/415 volt 3 phase system. Meaning the line to neutral utility voltage would be 240 volts and the line to line utility voltage would be 415 volts. The proper description for utility power is the the line to neutral voltage, the line to line voltages, and the number of phases. For instance just to name a few here in the US we have single phase 120/240 volt service (used in residential or very light commercial service), 3 phase 120/208 WYE (used in light commercial and light industrial), 3 phase 120/240 DELTA (used in light commercial and light industrial service), and 3 phase 277/480 WYE (used in heavy commercial and heavy industrial service). Most of these utility voltages are "inherited" at the property location when an entity acquires ownership of the location due to the high expense of installing new electrical equipment. The figure on the right of the diagram you uploaded is a figment of your imagination. There are no motors with a connection scheme like your diagram depicts and it has no factual basis whatsoever in AC induction motor theory. Your diagram tells me just how much "knowledge" of three phase systems you posses. For your education I have attached a REAL wiring diagram for a 6 lead wye/delta motor (AKA star/delta).



Instead of spending your time teaching your relatives how to suck eggs perhaps you should invest some time in learning about three phase power systems, AC induction motor theory and basic transformer theory so you could maintain a reasonable conversation about rotary phase converters.
As you have adamently stated the utility voltages in Australia are 240/415 volt 3 phase for commercial properties and 240 volt single phase for residential properties. What you have not stated is what voltage you want your idler motor to produce in your rotary phase converter (RPC). I assume you want to generate 240/415 volt 3 phase so you do not have to rewire/reconfigure any of the 3 phase equipment you are powering. Although if you can rewire/reconfigure your equipment to accept 240 volt 3 phase delta that would be the cheapest option since no step up transformer would be required. Nor have you completely listed ALL the data on the nameplate for the welder and any other 3 phase equipment you want to power with the your RPC.

regards
Junker2