# Multi speed motors (low / high)



## LATTC (Feb 12, 2012)

2 speed consequent pole motors
low L1-T1, L2-T2, L3-T3 and tie T4, T5, T6 together
high L1-T4, L2-T5, L3-T6


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## John Valdes (May 17, 2007)

An engineering handbook, a meter and a qualified electrician should be all it takes.


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## LATTC (Feb 12, 2012)

John Valdes said:


> An engineering handbook, a meter and a qualified electrician should be all it takes.


Most electricians will never have to deal with unmarked motor during their lifetime. 

Back when I was in school, all motor/xfmr leads were unmarked so we learned to ring out the motor before hooking anything up. 120v test lead, jumpers, meter, and pencil is all you need. 

If you can ring out a 3 phase bank then any motor should be a piece of cake.

Anyway, back to his question.
low speed should be parallel wye
high speed should be series delta


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## 123 (Oct 28, 2012)

Using Ohmmeter, It is not hard to find the windings.
What is the best way to find the way it is wound?
For example if a motor has 6 leads, each winding can be connected 2 different way. This changes the direction of the magnetic field.


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## JRaef (Mar 23, 2009)

You didn't say whether it is single phase or 3 phase, that makes a huge difference right there. If it's single phase it's easier to figure out, there is only one standard way they connect. If it's 3 phase, then it could be two different types, 2S2W or 2S1W. Then if it's is 1 winding type, it could be one of 3 different styles. Without knowing where you are starting from, you could be at this for days trying to figure it out.

Here is a shortcut if it is 3 phase. If the speeds are changed by contactors, then count the contactors. If it is obly 2 contactors, then it is 2S2W, if there are 3 contactors, then it is 2S1W. If it is 2S1W, then the wiring of the contactors will tell you the style, and from there you can look up starter wiring diagrams to figure out how the windings would be connected so you can determine how they should ring out. If it is a manual switch mechanism the end of the process is the same, but to determine the style, see if there is a part number on the switch and Google a wiring diagram. If there is nothing on the switch or is a brand that no longer exists, ring out the contacts and take note of which ones are jumped together, then look at the target charts of other manual speed change switches to see if something matches. most of them are fairly standardized, at least schematically. 

But if you have no nameplates, how can you hope to properly chose the conductor sizes and protect the motors?


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## pjmurph2002 (Sep 18, 2009)

thanks guys. the motors are single phase 120 volt (three and four wires comming from motor). no tags on the wires comming out of the motor - no markings inside of the motor splice / termination area.


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## LATTC (Feb 12, 2012)

pjmurph2002 said:


> thanks guys. the motors are single phase 120 volt (three and four wires comming from motor). no tags on the wires comming out of the motor - no markings inside of the motor splice / termination area.


Which one is it? 3 wires or 4 wires.
You should take some pictures. 

1st Method (4 wires)
Low L1-T1, L2-T2, open T3, T4, 
high L1-T3, L2-T4, OPEN T1, T2

2ND METHOD (4 WIRES)
LOW L1-T3, L2-T4, OPEN T1, T2
HIGH L1-T1, L2-T2, OPEN T3, T4

1ST METHOD (3 WIRES)
LOW L1-COM, L2-T1, OPEN T4
HIGH L1-COM, L2-T4, OPEN T1

2ND METHOD (3 WIRES)
LOW L1-T1, L2-T4, OPEN COM
HIGH L1-T1, L2-COM, TOGETHER T1, T4

3RD METHOD (3 WIRES)
LOW L1-T1, L2-COM, TOGETHER T1, T4
HIGH L1-T1, L2-T4, OPEN COM

4TH METHOD (3 WIRES)
LOW L1-COM, L2-A, OPEN B
HIGH L1-COM, L2-B, OPEN A


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