Single Phase to Three Phase Source

[gravi]

Dear Folks,

I am looking for smart solution for 3 Phase power source to test our 3 Phase equipments in lab. Unfortunately we don't have 3 Phase power source so can we design any single phase to 3 Phase converter, Our typical load on each phase would be 5 Amps. I have seen connecting a capacitor to drive 3 Phase induction motors from single phase can I apply the same here.

Thanking You,
Ravi Kumar Gangumolu

 

[ZASto]

You should buy an VFD (variable frequency drive) and play a little with it's parameters.

 

[BradtheRad]

Somewhere (perhaps at this message board) I saw advice to feed your single-phase power to a single-phase motor, whose shaft is physically connected to the shaft of a 3-phase motor.

The first motor drives the second motor. The second motor then becomes a generator of 3-phase power.

The second motor may need to be a certain type in order to perform satisfactorily.

 

[jpsganesh]

I have seen connecting a capacitor to drive 3 Phase induction motors from single phase can I apply the same here.

3 Ph motor can be run in 2 ph supply (when any one phase supply fails) with a capacitor. when supply passes through capacitor it'll make 90 deg phase shift which will be feeded to the motor. In this method motor will get little bit more heat than normal (3ph) operation because losses will be more. speed also will varry from normal operation with 3ph supply.

as "ZASto" suggested u can use VFD. But some VFD will shutdown automatically whn it detects no load and some VFD in setting we can disable it. before buying it u need to check this because for LAB purpose we may switch ON and OFF the load manytime. everytime power ON the VFD may be uncomfortable.

 

[chuckey]

If your mains voltage is 230 V, then you can run 415 star motors in the delta mode with the capacitor, max power ~60% of motor rating and you may need a 5 X larger cap to start motor on load, or use a VFD or rotary convertor.
If you cannot reconfigure your 415V motor, then you need a transformer to go from 230 -> 415 then proceed as above.
Frank

 

[schmitt trigger]

You can use a fully protected turnkey sytem like the one shown here:

https://www.phase-a-matic.com/RotaryDescription.htm

 

[goldsmith]

I am looking for smart solution for 3 Phase power source to test our 3 Phase equipments in lab. Unfortunately we don't have 3 Phase power source so can we design any single phase to 3 Phase converter, Our typical load on each phase would be 5 Amps. I have seen connecting a capacitor to drive 3 Phase induction motors from single phase can I apply the same here.

Hi Ravi Kumar
Of course you can not do the same and expect good specifications .
One of the simplest ways is using 6 mosfet inverter and three SPWM signals if sine wave is required .

Somewhere (perhaps at this message board) I saw advice to feed your single-phase power to a single-phase motor, whose shaft is physically connected to the shaft of a 3-phase motor.

The first motor drives the second motor. The second motor then becomes a generator of 3-phase power.

The second motor may need to be a certain type in order to perform satisfactorily.

Fascinating !
Also what Bradtherad advised is pretty simple and very acceptable . i have did it several times without any problem so i suggest you to do it too .


Best Wishes
Goldsmith

 

[BradtheRad]

To explore the idea of using coils and capacitors to shift the AC supply 120 degrees...

It is theoretically possible, using two stages...

Screenshot:



However a price is paid because the output is greatly attenuated.

With the unaltered 230 VAC, a 46 ohm load carries 5 A. You will not get anywhere near that amount after shifting the phase with coils or caps.

 

[goldsmith]

It is theoretically possible, using two stages...

Hi dear Bradtherad
it is also experimentally possible but it has several disadvantages too . so in precise cases it won't be good and of course it would deliver large amount of price for the user and lower quality in compare with the delivered power . ( as you noticed about it too . )
and also another problem is shifting which can be with bad tolerances . so for labs it is not good .

My Best Regards
Goldsmith