Two Phase Motor

[RMBcapecod]

How do I wire a two phase motor from a single phase power supply? The motor control panel has four terminals to connect to.

 

[busbar]

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?

 

[jbartos]

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

 

[GusD]

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

 

[busbar]

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.

 

[peebee]

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. . . .