Created Date: March 26,2012

Created by: dieseltwitch

I'll be powering electronics though so I'm not sure now they would deal no pure sing wave.

Plus dont AD VFD have direction to know when they are not hooked to a "motor "

I 've seen it done before but the problem is that the motor slows down as the load increases. and the Hz Drop. if I have the drive motor on a VFD it can automaticly compensate.

Created Date: March 26,2012

Created by: Cap

Sounds like you are trying to Build what is called an 'Inductive Generator '..

Try this ..

If you take a 3 Phase 1800 rpm motor, and hook a Capicator to the 'third Leg ', then you have what is know as a 'Rotary Converter '.. The Size of the Motor, and the Size of the Capicator are the Varables..

I run Rotary Converters for my 3 Phase Machines in the Barn.. but I Use the Machine Motor as it's own Converter..

For every 1 Hp of motor Size, you need 25 MF of running Capacatance. When running the 'third Leg ' voltage will be higher than the Other two..

This motor set up likely will not self start.. To get my Motors to self start, I hook a starting Cap of 10 * the MF of the Running cap. the Starting cap is ONLY hooked across the Running Cap during Starting Conditions..

I use a 'Voltage Sensetive Relay ' as my Start Circuit Driver.

The Logic is This..

When the 'Cap Driven 3 Phase Motor ' is Hooked across the Line ( Single Phase ) to Start, the Third Leg becomes a Voltage Divider of the Other Two Lines, and the Voltage of that Leg will drop to ~120 Volts ( 1/2 of the 240 volt line ).. and the Start Capicator Relay 'drops Out ' ( as it was reading a 240 Volt line with the Motor Unhooked ) and lets the N/C Contact of the Start Relay, hook the Start Cap to the Running Cap in Paralell. When the Motor Increases in speed, and Starts to get to Sync Speed with the Line, the Voltage on the Third Leg, will jump to about 250 Volts ( Depends if you are measuring across the Cap or the Other Line Leg ).. when the Third Leg reaches above 200 some volts, the Voltage Sensitive Relay is set to pull in, and The N/C Contact will take the Start Cap off the Line, and ONLY the Run Cap is Doing the Phase Shift for the Motor.. and the Motor will self Start..

After you have the 'Phase Shifted ' Motor System running then hook it to a 240/480 Transformer to get your 480 Volts you need..

If you look at the Waveform with a Scope, you will see some distortion, and the Phases will not be 120 deg apart.. and the Different lines of the 480 will have different waveforms.. but it still will be 60 HZ..

EDIT: You can also do this without using the Transformer, by having the 'Center Star Windings ' of the Motor running on the 3 Phase Converter trick, and having the 'Outer Star Winding ' drive your 480 Volt System..

This type of wiring get very complicated ( I 've Done it for Trials).. but for 'Clean Rube Goldburg ', I'd stick with the Transformer.

Cap

Created Date: March 26,2012

Created by: dieseltwitch

Sounds like you are trying to Build what is called an 'Inductive Generator '..

Try this ..

If you take a 3 Phase 1800 rpm motor, and hook a Capicator to the 'third Leg ', then you have what is know as a 'Rotary Converter '.. The Size of the Motor, and the Size of the Capicator are the Varables..

I run Rotary Converters for my 3 Phase Machines in the Barn.. but I Use the Machine Motor as it's own Converter..

For every 1 Hp of motor Size, you need 25 MF of running Capacatance. When running the 'third Leg ' voltage will be higher than the Other two..

This motor set up likely will not self start.. To get my Motors to self start, I hook a starting Cap of 10 * the MF of the Running cap. the Starting cap is ONLY hooked across the Running Cap during Starting Conditions..

I use a 'Voltage Sensetive Relay ' as my Start Circuit Driver.

The Logic is This..

When the 'Cap Driven 3 Phase Motor ' is Hooked across the Line ( Single Phase ) to Start, the Third Leg becomes a Voltage Divider of the Other Two Lines, and the Voltage of that Leg will drop to ~120 Volts ( 1/2 of the 240 volt line ).. and the Start Capicator Relay 'drops Out ' ( as it was reading a 240 Volt line with the Motor Unhooked ) and lets the N/C Contact of the Start Relay, hook the Start Cap to the Running Cap in Paralell. When the Motor Increases in speed, and Starts to get to Sync Speed with the Line, the Voltage on the Third Leg, will jump to about 250 Volts ( Depends if you are measuring across the Cap or the Other Line Leg ).. when the Third Leg reaches above 200 some volts, the Voltage Sensitive Relay is set to pull in, and The N/C Contact will take the Start Cap off the Line, and ONLY the Run Cap is Doing the Phase Shift for the Motor.. and the Motor will self Start..

After you have the 'Phase Shifted ' Motor System running then hook it to a 240/480 Transformer to get your 480 Volts you need..

If you look at the Waveform with a Scope, you will see some distortion, and the Phases will not be 120 deg apart.. and the Different lines of the 480 will have different waveforms.. but it still will be 60 HZ..

EDIT: You can also do this without using the Transformer, by having the 'Center Star Windings ' of the Motor running on the 3 Phase Converter trick, and having the 'Outer Star Winding ' drive your 480 Volt System..

This type of wiring get very complicated ( I 've Done it for Trials).. but for 'Clean Rube Goldburg ', I'd stick with the Transformer.

Cap

I'm a little confused. do you put the "rotary converter " on the output of the driven motor do you do USE that setup on the device you are trying to run?

I need to the voltage and the hz but not really the amps. What Im doing is building a VFD/control cabinet and I need to test it before I install it. problem is I don't have 3P at my shop... so I'm trying to find a simple way to develop SAFE 3P for powering on the drives, Power supplies, step down transformers (480 - 120)....

Are we on the same page?

Created Date: March 26,2012

Created by: Cap

Yes.. same page..

The 3 Phase 'Rotary Converter ', can either be a Separate Stand Alone Motor, that is Larger than the Motor you are trying to drive, or it can be THE motor you are trying to drive.. Either case you want to feed the '3rd Leg ' with 25 MF per HP.

If you are trying to make a Stand Alone unit, then you run the Two Wires to the Rotary Converter.. with the Start Cap, run Cap, and Voltage Sensetive Relay somewhere around the Motor Box.. then OUT from that you Run the Three Wires to what ever the 3 Phase load is.. the 3 Phase Feed is taken from T1/T2/T3 of the Motor..

OR.. you can add the Start 'stuff ' to a Motor that is installed in the Machine, and have the Motor be it's own Converter..

My set up, has my Lathe ( 3 HP ) with all the Start Stuff mounted in the Lathe.. and I start it like it was a 3 Phase Machine.. just can't instant reverse..

My Mill, does not like the 'shifted Power ' and tends to get hot if I try to run it ONLY on the Cap Bank.. So when I run the Mill Motor.. I have the Lathe also running in what is called a 'Pony Motor ' state.. the Lathe ( Not Loaded ) will help get the Power Close Enough so the mill will Like it..

In your Application, you will likely set up just a 'Pony Motor ' that has the 3 phase conversion stuff on it.. and then grab the 'somewhat 3 Phase ' power out of the Pony Motor, and feed the 240/480 transformer..

The Pony Motor will stay running as a 'Rotary Phase Converter ' while you are making 240 3Phase for the Transformer. Then the 480 out will feed your VS enclosure.

Take a 1 hp or so 3 phase motor, and wire it up to run 240.. then wire a 25 MF Motor Run Cap between leggs 2 and 3 of the Motor..

Then take a 240 Extension Cord and wire the Two Hot leads to the Leggs 1 and 2 of the Motor.. you will see that leg 3, is Cap Driven from Leg Two.. when you plug in the 240 Extension Cord the Motor will Grown and SLOWLEY start to turn.. IF the bearing drag is not to great, and the Motor has good Start Torque, it will start to spin Faster and Faster.. as soon as it reaches CLOSE to Sync Speed it will learch to Speed.. IF you have a Motor that will do this ( Low Start Drag, and High Start Torque ) then you do not need to mess with all the 'start Krap '.. Just do not hook ANY loads ( Electrical or Mechianical ) to the Motor till it's at Speed.. Once it there, your Golden..

Some have also added a 'starter Coard ', Like on a lawnmower, to get the Poney motor to speed.. this also works..

You will have to check to voltage out to the VS Drives, as it will be unballanced.. ( Arn't we all? ).. and iff you add or subtract some Capitance, you can get it closer.. Also adding more Motors unloaded to the Ststem will help fix the Voltage Unballance..

The only other way is to do a Motor Generator set up like you were talking about.. I have a 3/4 HP 3 phase 240 belt drive generator, that came out of Diesel Refer Box.. they are used to run the Fans in the Container.. You might be able to find one of them for your experiments..

Cap

Created Date: March 26,2012

Created by: Cap

The Picture that you Posted, is of a M/G Set.. Motor Generator..

That is the Cleanest way to get 3 Phase Power from Single Phase.. NOT the Cheapest..

Caps are not used in generators, because thy have Wound Rotors.. Motors ( Usually ) do not have Wound Rotors.. ( Well they are, but the Secondary is Short Circuted.. and Generally not Discussed as Wound )..

Another way is to just go, is to rent a Diesel Generator, that will do 3 Phase power.. then if it will do 480 good.. else, use the Transformer to get your 480 from the 208 or 240 line.. depends on the Generator Type..

Cap