Need help with Delta Y transformer to make 3 phase. 2

[JR2]

I'm wanting to produce 240 volt 3 phase using 240 volt single phase, with a transformer.
Will a Delta Y 120-240-480 volt transformer convert 240 single phase in, to 240 3 phase out? I'm in need of 25 hp with 3 phase.
Is there a transformer that will give me close to 240 volts on each of the three legs?
I will appreciate help with this problem.
Thanks, Elmer (in Missouri)

 

[PierreR]

JR2,
Each phase of 3 phase power is 120 degrees apart. you cannot make 3 phase power from a single phase without applying phase shift devices.
Furthermore, keep in mind that even with phase shifting gear, you will take all the power from the single phase.

 

[busbar]

As described, a transformer will not do the job. Use this site’s search function for extensive discussion on the matter.

Depending on 1ø supply-circuit characteristics, you may be able to use a [beefy] rotary or static ‘phase converter’ like that at

http://www.gwm4-3phase.com

 

[simtricity]

Hi JR2
PLEASE EXPAND ON YOUR PROPLEM.ARE YOU TRYING TO RUN 3 PHASE MOTORS FROM A 240V SUPPLY?

 

[PierreR]

JR2,

Busbar is correct. However, it is likely that using 3-phase power with a 3-phase (protected) transformer and the required cabling for 25 hp will be cheaper than purchasing, installing and configuring a converter.

Do you have 3-phase power available at your location? Is it far from the 25 hp?

 

[busbar]

JR2 — Should you have more time and spare parts than money, one approach may be

http://www.capacitorconvertors.com/staticinstructions.pdf

 

[jbartos]

Suggestion: Nowadays, electronic converters can produce AC-DC-AC conversion such that the 240VAC is rectified and DC bus is powered. Then, DC-AC inverter produces 3Ø power supply suitable to power the 25HP motor.
Visit

http://www.thomasregister.com

and type Converters: Phase under Product or Service, which will return 62 companies to approach to

 

[JR2]

I have several 3 phase motors to run machines. I only have 240 Volt single phase at my service. The 3 phase lines are 3 miles away. It would cost way to much money to have the electric company bring it to me.
I have been looking at a 25 or 30 hp 3 phase motor to hook up as a generator. I wired a 10 hp 3 phase motor up as a generator, using the two 120 volt wires to two legs. I got the motor spinning with the help of a 1/2 hp single phase motor. When the motor started running on it's own, I ran a check across the legs. Using T1 & T2, I got 205 volts. Using T1 & T 3, I got 215 volts. Using T2 & T3, I got 235 volts. I could use capasitors to bring them closer to the 240 volts but I'm not that sure I could work with capasitors. I was given information that the Delta-Y would work better but I wanted to check with experts first.
It sounds like I need to stick with a 3 phase motor for a generator.
I thank you all for your help on this problem. Can you tell me what the voltage difference can be on the three legs to have a usable 3 phase voltage?
Elmer

 

[jbartos]

Suggestion: The voltage difference on the three legs should be equal to the standard system voltage that would be suitable for the loads that have rated terminal voltage reserved for the specified system voltage. It may be difficult to produce it properly and maintain it properly with the motor set-up. Also, the motors seem to be locked up by this power generation. It would be prudent to look into the AC-DC-AC power converters. Visit

http://www.thomasregister.com

and type Converters: Phase under Product or Service, which will return 62 companies to approach to for an appropriate converter.

 

[Lakey]

Hi,

If I’ve understood correctly you’re trying to run a 3-phase motor off a single-phase supply.


Suggestion:

Temporary Solution:

Configure your 3-P motor to delta. Connect L & N across one of the windings and connect a capacitor across the other winding adjacent to L, thus phase shifting.

The capacitor value is likely to be between one and ten microfarads. The cap value should adjusted so that motor’s amp rating is not exceeded.

I have not tried this myself, but I would be interested to know how effective it is.


Regards,

 

[jbartos]

Comment on the previous posting. The motor will start; however, the shaft HP will be somewhat less than rated. This may lead to motor overloading.

 

[FACB25]

Here is one of the best discussions of a rotary phase converter I've found.

http://home.att.net/~waterfront-woods/Articles/phaseconverter.htm

My suggestion is:
a) buy a motor that is larger than all loads combined and make a rotary phase converter and go. I've seen several installations and many happy users.
b) make a motor-generator. Couple a single phase motor to a 3 phase generator using a substancial flywheel. This is a little costier, but does have some advantages (isolation, etc.) and usually comes in cheaper than solid state converters.