Problems on trasformer

[rambozhou]

I have a case on hand: to design a transformer to realize the function that change power from single phase to triple phase, i have no idea on how to figure it out.
I have seen some product on-line which is a static converter, but i am not sure if it's a transformer or some other solutions.

 

[weh3]

Try a search on "phase converter". Is this for a rural application?

Will-I-Am

 

[aolalde]

Certainly is not a classic transformer. Transformers modify the voltage but not the phases or frequency.
For an electronic solution, you need a Driver to convert the 1-phase AC to DC and then to 3-Phase AC. Remember that for a true 3 phase system you need three identical AC voltages out of phase 120° electrical one from each other.

For electro-mechanical solution, the only true rotating single phase to 3-phase converter is made with a single phase AC motor driving a synchronous 3-phase generator.

 

[Marke]

Hello rambozhou

To create the three phase output from a single phase, you are going to need to use a three phase generator. This can take the form of a rotating three phase machine driven by a single phase machine, or a sold state inverter.

It is possible to use a seies of single phase transformers and phase shifting components to generate a three phase voltage, but if you require any "power" from the system, this is not really a practical solution.

For low power requirements with only moderate regulation, you can use a three phase motor driven by a single phase provided that the load is low. You will need to use some means to get the motor to spin to full speed in the correct direction initially.

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[rambozhou]

Yes, it is accomplished by using phase shifting components (such as capacitor)on the primary side,since the load is 3 phase motor,the current can be balanced only on the full load situation.I have got some information on that in a transformer design book.

Thanks

 

[buzzp]

rambo,
Is what your proposing supposed to give 120 degree seperation between phases? I doubt it. I have heard of using caps but you never get the 120 degree shift using only caps (correct me if I am wrong).

 

[mc5w]

Check with a company named Ronk. They are the leaders in single phase to 3-phase converters. They have several diferent technologies that you can use:

1. One of them is their Add-A-Phase, which operates a single motor as a permanent split capacitor motor aided by a Steinmetz Balancer Set to get it up to full power. The capacitor in this system is connected to a tapped autotransformer to vary the amount of phase conversion to match the load. The motor serves as a 3-phase voltage source to make the Steinmetz Balancer Set work.

2. They also have a rotary phase converter that also connects the capacitor to a tapped autotransformer to vary the amount of phase conversion when you have a large number of motors turning on and off or which have cyclic loading.

3. Their classic technology is a rotary phase converter with a fixed capacitor, primarily for applications where the motor load is more or less fixed such as a sewage plant.

There is also a thread in this forum where I explain rotary and static phase conversion principles. Most phase converters use both rotary and static principles. This is because you need a 3-phase voltage source to make static conversion to work and a power factor improvement capacitor can use an induction motor's inductance to form a Steinmetz Balancer Set.