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Two Phase Motor

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RMBcapecod

Electrical
Apr 28, 2003
2
How do I wire a two phase motor from a single phase power supply? The motor control panel has four terminals to connect to.
 
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RMB — Are you certain it's a two-phase motor? They are rare. Would you post the motor nameplate data, and describe the control panel?
 
Suggestion: The two-phase motor has direct and quadrature-axis stator winding. This may correspond to four wires that you have. The quadrature-axis winding is supposed to have either a resistor or capacitor in series with the quadrature-axis winding for starting purposes.
Reference:
1. Gordon R. Slemon "Magnetoelectric Devices, Transducers, Transformers, and Machines," John Wiley and Sons, Inc., 1966, Section 5.8.4 Single Phase Induction Motor
 
Hi RBMcapecod.

Straight out of the Rosenberg motor bible.
Interesting,I am older than any 59 year old, and I have never even seen one of those things.Even in the days when I was rewinding motors.
He says that a TWO phase is the same as a Three phase as far as the coil groups and the number of coils.
No mention of using single phase power,however;you can use 3 phase power but the windings have to be modified somewhat to power a 2 phase motor .
This is done by means of a (T) or Scott connection.This connection is made by connecting the end of phase A to the center of phase B.You have to disconnect some coils from phase A to balance the split phase B.Sorry I can'tell you how it would run.
I don't know if you can run a Two phase by using Capacitors just like to run a Three phase from a single phase source.
Best I can do RMB


GusD
 

Off topic, but C F Scott, the inventor in 1894, stated: In considering the marked advantage of the two-phase system for distribution and of the three-phase system for transmission, it occurred to me that that a combination of the two systems night secure the advantages of both, and I have worked out a simple and effective method of accomplishing this result. From James C. Brittain, “Charles F. Scott: A Pioneer in Electrical Power Engineering,” Industry Applications Magazine, Nov/Dec 2002 pp.6-8

Though not exactly “cutting edge,” apparently there are some two-phase systems in the Philadelphia and New York City areas. PECO lists 120/240V 2ø 5-wire and 2400V 2ø 3-wire{!} service in their tarriff. Con Ed lists 1950-volt{!} 2ø availability in their general conditions.
A NYC description of the Macombs Dam turnstile bridge {1895} listed having two two-phase motors. Oddly, 1999 NEC Table 430-149 concerns two-phase motor characteristics.
 
We've got some mid-point-grounded delta 120/240 here in Chicago, too. It's an oddball, but there's a few around. They often lead to change orders on remodeling projects cause you think you're dealing with 120/208 up until you get the call from the contractor. . . .
 
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