Need refresher course in AC motor reversal

[PineRidge]

Have a fractional HP 110V AC motor that I'll need in a new project. I would like to add a reversing function to the motor but can't find out how to wire the switch.

For the sake of simplicity I'm only showing the two wires within the motor control box that will need to be reversed to do the job. My question is this: Can I add a SPDT center off switch and wire it like my diagram shows to reverse and stop/start the AC motor without harm to the motor?

 

[techman]

If it is a single phase motor, chances are it is not reversible. Most split phase and capacitor start/run motors can not be reversed. If the motor is designed to be reversed, there should be a wiring diagram on a plate on the motor. Also any reversible motor will have more than 2 wires.

the diagram you showed would be for a permanent magnet DC motor only.

paul

 

[PineRidge]

Paul it is a single phase reversible AC furnace blower motor and naturally there are more wires in the control box including the power wires than the 2 that I showed. However I saw no need to show them since it would merely cloud the question. The plate on the motor says to merely reverse the black and red wire for rotation reversal. Each of these two wires has a 1/4" spade clip on them and they are attached to a phenolic board on the motor itself. Rather than physically opening the motor and changing the wires manually we would like an external switch to do the deed.

 

[chim]

You could probably extend the red and black and use a 4-way switch. Red and black out to the one end of the switch, and another red and black back to the terminals.....................chim

 

[PineRidge]

Chim I'm not familiar with a four way switch, so I'm sorry not following. A Google search for a 4 way switch shows me a picture of a switch with 4 terminals. switch diagrams

 

[memenzel]

You need a reversing drum switch. They are a three position switch, forward - off - reverse. You can find them at www.grainger.com.

Mike

 

[midlf]

The simple answer is YES. I would not reverse the motor while it was running unless I knew for sure this was an acceptable practice for this motor. Other than that your switch diagram will work as you want.

 

[chim]

</font><font color="blue" class="small">( The simple answer is YES. I would not reverse the motor while it was running unless I knew for sure this was an acceptable practice for this motor. Other than that your switch diagram will work as you want. )</font>
Good catch. I wasn't thinking that he would use the 4-way except while the power is off............chim

 

[chim]

PineRidge, check this page...............chim
http://www.lightingfacts.com/3w4w%20how.htm

 

[PineRidge]

Chim looking at your link I don't know why a 4 way wouldn't work either. It just wouldn't act as an on/off switch, just a reversing mechanism. Thanks!