Single phase to 3phase 2

[Pucp]

I want to start a 3phase motor with a single phase, I have used a capacitor with a third leg. I know that I can buy a converter, but that is what I do not want to do. I have made some tests and with one motor (2Kw) the current in the direct line(the line that does not have to do with the third leg) is too high (12 A) when the nominal is 5 A. In this I have also put a capacitor between the direct line and the third leg but when I start the circuit I have not found any current in this line as if it does not exist. I will appreciate your help.

 

[teco]

pucplease advise power requirements,speed and single phase volts also has the 3phase motor 6 leads out if so what is the connection and volts at normal 3phase supply.
kind regds.

 

[electricpete]

There has been a lot of discussion on this subject at alt.engineering.electrical newsgroup. The following search produced at least three threads on this subject:

http://groups.google.com/groups?q=s...r&hl=en&meta=group=alt.engineering.electrical

 

[busbar]

Also,

http://groups.google.com/groups?q=3+phase+motors&hl=en&lr=lang_en&btnG=Google+Search&meta=

turns up a bunch of hits in rec.crafts.metalworking

 

[jbartos]

Suggestion: Visit

http://web.wt.net/~hmsc/phconv/phconv.htm

for more info

 

[ctolbert]

This website I found a while a go. It shows how someone made one.

http://www.team.net/

http://www/shop-talk/hm3phase.html

It's like the pony-motor concept we used in the Navy. I saw something similar on a ship commisioned in 44.....this was in 93....very vintage.

Carl

 

[Pucp]

Thanks a lot for your replies. I have read the web pages you mentioned, but all they do is just trial and error as I. Do somebody make a formal electrical calculus of the circuit by result of connecting the capacitor (I mean angles phases, formula for the capacitor value)??. It is supposed that if I change from one to another capacitor the angles phases and by the way the current changes very much??. One the things they said is that is better to use an IDLER motor, by the way what is that??, is only another motor?, it is not coupled, isn't it???, it is only used as a generator?. I prefer not to use another motor, but I don't know, in my experiments my motor runs well (without load), but with load things changes...one of the lines, the direct one, "pulls" much more current (2x) than the others (the other direct and the third leg). My pump (coupled directly with the motor) works but the current is 2x the nominal current, so it a matter of time for my motor to "die", also I don´t know if it is going to be useful for my application, but I have to solve it.
For TECO, this motor is an A2Q motor (from WEG), is it used coupled directly with a water pump, they work both summerged so we obtain more power from the motor due to the water cooling. The data (for normal 3phase supply) you require is the following:
Power 2 HP (1,47 Kw), but we obtain almost 2 Kw
Two poles 60Hz 220V 3500rpm Double triangle conection
Cp/Cn 3
Cm/Cn 2.8
Ip/In 6.6
Thanks in advance

 

[teco]

pucp:-we understand now that you want to start and run the motor on single phase.the type of connection is called a stynmetz, the motor is connected in delta and a capacitor is placed across one leg of the delta bridge and single phase is then supplied to the exsisting phase leg with the neutral connected to either side of the capacitor(which side depends on rotation).1.5 kw is the max size for this type of connection the capacitor size would be around 80-100mf(this will be a working cap not a start cap)and rated at 400 volt.should you require connection diag and performance data please advise fax no or "e"mail address.
hope this will help.
kind regds.

 

[Pucp]

Thanks again, I will appreciate if you email me the connection diagram and performance data please.

My email is zuazo.ia@pucp.edu.pe

I have done what I have read and I find that with 1.1 kW my pump works fine, I have found a 45 uF capacitor (more less),with no current balance but with the higher current lower than the nominal and I would sent you my results if you want. But with the 2 kW pump (the same motor but a different impeller) I can not balance the current (82 uF the best), and one of the lines "pulls" more current than the nominal. Thanks in advance, I hope we will continue in touch.