Phase converter/autotransformer 220 in / 440 out
Phase converter/autotransformer 220 in / 440 out
(OP)
Hello, I am new to the group and after reading several posts I appear to be in the right place. First off I am NOT electrical, but rather mechanical so PLEASE go easy on me.
Problem in Nutshell:
I have a piece of machinery that is 440V 3 Phase (6hp).
I have 220V Single phase service.
I have a 220/440V 10hp that i wanted to use as my rotary converter.
I was TOLD that I could have this motor be BOTH the phase converter and the step up transformer if I wired it for the 440V configuration and center tapped the 220V coming in. Whatever that means.
FWIW I plan on using both a Start cap as well as run caps from both lines to generate a makeshift 3rd leg going into the idler motor. Given all this all's I can make out of this would be to hook up the motor (which is "Y" configured BTW)
Something like this:
T1 connected to Load 1
T2 connected to Load 2
T3 connected to Load 3
L1 connects to T7,T4
L2 connects to T8,T5
L3 connects to T9,T6
But after looking at this I am not so certain I am heading in the right direction.
This seams theoretically possible, btu I am tripping over the actual connections.
Any help is greatly appreciated.
Problem in Nutshell:
I have a piece of machinery that is 440V 3 Phase (6hp).
I have 220V Single phase service.
I have a 220/440V 10hp that i wanted to use as my rotary converter.
I was TOLD that I could have this motor be BOTH the phase converter and the step up transformer if I wired it for the 440V configuration and center tapped the 220V coming in. Whatever that means.
FWIW I plan on using both a Start cap as well as run caps from both lines to generate a makeshift 3rd leg going into the idler motor. Given all this all's I can make out of this would be to hook up the motor (which is "Y" configured BTW)
Something like this:
T1 connected to Load 1
T2 connected to Load 2
T3 connected to Load 3
L1 connects to T7,T4
L2 connects to T8,T5
L3 connects to T9,T6
But after looking at this I am not so certain I am heading in the right direction.
This seams theoretically possible, btu I am tripping over the actual connections.
Any help is greatly appreciated.





RE: Phase converter/autotransformer 220 in / 440 out
In various phase-converter discussions, I don’t remember anyone mentioning use of the converter motor as an autotransformer. It may likely require additional derating of the converter motor.
There has been a fair amount of discussion here, that should show up with a search.
RE: Phase converter/autotransformer 220 in / 440 out
Yes, you could get 220V out of a 220/440V motor by tapping the connections. It's the current you need for your load that is the problem. What do you think inrush current for the motor you are trying to start will do to the windings of the motor from which you are trying to get it? (Let's not even talk about your 'makeshift 3rd leg' from capacitors.)
The truth is, if I were given these components and your plan for a dare, I might be able to make your 3-phase motor start(once, anyway...or at least begin to start once, anyway).
RE: Phase converter/autotransformer 220 in / 440 out
FWIW the Idler motor IS 3 Phase as I know no other way to make a "make shift" phase converter using a single phase motor.
RE: Phase converter/autotransformer 220 in / 440 out
RE: Phase converter/autotransformer 220 in / 440 out
RE: Phase converter/autotransformer 220 in / 440 out
http://home.earthlink.net/~ojmsmith/indexd.html
and then go and get a copy of Smith's patents. They will tell you how to do what you are asking how to do. It is really a very clever use of the magnetics in the motor. It is all about how to run any 3 phase motor from a single phase supply. Voltage adjustment included. It may elimiate your need to use the 10HP motor as a phase converter.
Please post the results of what you decide to do.
RE: Phase converter/autotransformer 220 in / 440 out
RE: Phase converter/autotransformer 220 in / 440 out
RE: Phase converter/autotransformer 220 in / 440 out
I wired up a 10 Hp 3 phase motor to put 220V single phase IN and got 440V 3 phase out (Well actually idle voltage is closer to 480 but drops down to 440V when the machine is running).
Currently everything is "jerry rigged" just for testing, but it is wired like this:
L1 to L3 has a 40mfd Run cap
L2 to L3 has a 80mfd Run cap
L1 to L3 has right about 900mfd Start cap
Motor wired 440 w/220 fed into the "center" of the windings.
"old" inputs now output 440-480 (T1 T2 T3)
Initially I am running a 5Hp 440V 3phase Nibbler - It starts (full speed) in less than a second or two.
I ran it for about a 1/2 hour - neither motor got hot - both were barely warm.
That was the good news -yea!
The bad news is that I cannot start the motor in "high" speed. The nibbler has a dual speed motor and it worked great (start/stop) at the low speed 1750rpm, but when I tried to start it (from a dead stop) in the high speed (3500rpm) it stalled my converter motor. I am considering adding a flywheel to the idler or maybe even some circuit to sense voltage and have the start caps kick back in when needed, but before any of that I first need to do some more checking out of the current motor and contactor set to make sure that they are NOT the culprits.
Just thought you guys might like to know how this is going so far.
RE: Phase converter/autotransformer 220 in / 440 out
Try wiring the two {or more} run capacitors in parallel on one side; id est, everything L1-L3 and none L1-L2.
RE: Phase converter/autotransformer 220 in / 440 out