# How To Reverse Rotation Of 1 Phase Motor?



## trg-s338 (Jun 12, 2015)

I've acquired a Delta brand model 62-185, Marathon manufactured single phase motor I want to use on my just built belt grinder.  It is 2 HP, 10A, 230V, C-face motor.  May have originally been on a Delta DC33 Planer.  My knowledge of electric motors is limited but in searching information, I've come to believe this is a capacitor start-run motor.  It has a 30 uF as well as a 230-276 uF capacitors on it.  I assume the larger one is the start capacitor disconnected by a internal centrifugal switch at the appropriate speed.  This motor spins counter-clockwise and I need to reverse the rotation.  I hope to not have to dismantle/remove the end bell of the motor.  Can reverse be achieved by simply switching start capacitor terminal wires (colored red and yellow, a black wire connects both capacitors)?  If not, I could use some advise on how to go about  it?  The power switch/fuse box has a blue and red wire to it from the motor.  Your thoughts on this would be greatly appreciated.  Thanks.


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## Ulma Doctor (Jun 12, 2015)

a picture of the wiring end of the motor would help.
some motors are not reversible, some are reversible


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## RJSakowski (Jun 12, 2015)

The start winding has to somehow be reversed.  On reversible motors, the winding leads are brought out to an access point where they can be interchanged.  One end of the winding may be connected to the start capacitor or to the centrifugal switch.  The winding, the start capacitor, and the switch are wired in series and can be reversed as a unit if the winding leads are not accessible.  On unidirectional motors, the windings may be connected internally.  I have successfully traced down the internal connections and reversed them but it required a teardown of the motor to get at the leads. There are a number of threads on the site which have wiring diagrams for capacitor start/capacitor run motors. A search should pull them up. Try http://www.hobby-machinist.com/threads/another-wiring-job.32378/#post-274656 for one.


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## trg-s338 (Jun 13, 2015)

Opened up the back of the motor. Attempting first time upload of photos.  Within the back plate is a switch that looks like contact points on auto engine distributor of old. This is positioned between the capacitors it seems.


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## JimDawson (Jun 13, 2015)

Are there no wiring diagrams on the data plate on the motor?  Maybe inside the switch box?


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## RJSakowski (Jun 13, 2015)

It looks like you have a unidirectional motor.  If the motor is unidirectional, it usually state CW or CCW on the data plate. 

I see the two feed (red and blue)wires coming in from the black box.  One of the yellow wires runs from the capacitor to the switch.  It looks like a brown wire runs from the switch to the capacitor? 

Most likely the other end of the start winding is connected to the run winding somewhere.  The connection probably be taped over.  It would be necessary to break that internal connection and run that end  the start  winding to wherever the other end of the winding is connected and to connect that other end to the internal connection point. In other words, swap the leads end for end.  Before changing anything, identify the winding leads with an ohmmeter or circuit tracer.  

Changing rotation on a unidirectional motor isn't difficult but you have to pay attention to details.  If you think it is too complicated, consider  mechanically reversing the motor.  If that is not possible, an electric motor repair shop should be able to reverse the direction.


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## trg-s338 (Jun 13, 2015)

From what I see, I've drawn a schematic.  I teased out the blue wire end of the windings and find three wires attached to it.  Two of the wires beep continuity with the Yellow "B" side of the centrifugal switch.  The third wire beeps continuity with the red wire off of the large 273 uF black capacitor. 

* Would it be correct to presume that one of the 2 wires continuous with the "B" side switch  is the other end of the start winding and is dropped out when the motor is at speed?  Any guesses on what that second wire to the "B" side might be?  This throws off my schematic.

* Would it also be right to presume that the 3rd wire that communicates with the red wire of the  270 uF large black capacitor is the run winding?

It's very likely my inexperience leads to some wrong conclusions here so I'll value any input on this.  Thanks for your time.


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## John Hasler (Jun 13, 2015)

Your schematic is incorrect.  The centrifugal switch must disconnect the 270mfd start capacitor when the motor is up to speed while leaving the 30mfd run capacitor in the circuit.  The run winding must always be connected across line and neutral.


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## trg-s338 (Jun 13, 2015)

I removed the switch from the back plate and discovered my error as you prompted me John, thanks.  I corrected the schematic.  The continuity test results are as above but I have a sense that I've got my conclusions on the windings backwards.  Still at a loss on the the third wire at the blue lead.


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## John Hasler (Jun 13, 2015)

Note that reversing *either* winding (but not both) will reverse the motor.


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## trg-s338 (Jun 14, 2015)

John Hasler said:


> Note that reversing *either* winding (but not both) will reverse the motor.



Hoooraaayyhh!!  I have made my motor rotate clockwise!  At past midnight, I have achieved success!  The principle is actually easy.  Thanks to John Hasler and RJSakowski, I ended up flipping the start winding.  Initially, it was intimidating for a motor newbie like me to rip into the motor and windings but focus and making the effort to understand your advise helped me figure it out.  

I'll be firing up my home built belt grinder tomorrow on her maiden voyage to see if everything works.  All will be made possible with the motor now spinning the right way for the machine.  If it's serviceable,  I'll post on it at the Beginner's Forum.  Thanks a  million, guys!


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## rdhem2 (Jun 14, 2015)

A couple basic side notes for the future to help understand and remember the discussed topic.  In the case of capacitors, when faced with dual capacitors, metal cased capacitors are RUN capacitors and plastic cased capacitors are START capacitors.  Standard NEMA wire coding/marking is for the start leads are numbered #5 and #8, else color coded RED and BLACK.  Swapping the connection of these two wires in a single phase single or dual voltage motor will reverse the direction of rotation.  Now lets get back to making *SWARF!*


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## trg-s338 (Jun 14, 2015)

Thank you for the info.  Perhaps its because my motor is older, the leads were not labeled in any way.  Now I know.  I did not take particular close attention but the smaller value cap is metal cased but the other black one I'll have to take a closer look at.  Yes, in this case I'll be making grit!


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