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05-09-2008, 10:07 AM #1
Wiring a single phase motor to drum switch
My question isn't about phase conversions but i figured this board had the most knowledgable electricians. I converted my Rockwell mill to a single phase motor years ago. I have been running it with the original drum switch turning in one direction (CCW). I would like to wire it to reverse also. According to the instructions on the motor, a GE 3/4 hp capacitor start/capacitor run, two wires have to be switched in order to reverse rotation. These wires are not the power wires but wires attached to the motor. How can I do this with the drum switch?
05-09-2008, 10:40 AM #2
Do you have a diagram of the drum switch showing the contact setup ? Most single phase motors can be reversed by interchanging #5 lead with #8 lead of the motor
05-09-2008, 12:15 PM #3
Basically you will need a drum switch with enough contacts to do the job. For single phase you will need a 4 pole drum switch to be able to break both hots and to switch the leads 5 and 8 (which you will need to bring from the motor to the drum switch).
You will need to post a diagram of your drum switch for anyone to be able to tell you how to wire it as there are more than one type.
05-09-2008, 12:30 PM #4
I have a three pole drum switch. No wonder I couldn't figure this out. I think I will leave it a one way until I have to change.
05-09-2008, 02:50 PM #5
Only three poles are required to perform both the motor controller and disconnect functions.
First, you have to decide whether you are going to reverse the run winding or reverse the start winding.
Usually, it is best to reverse the start winding, as this makes conversion from 120 to 240, or from 240 to 120 a little easier.
Let's say your drum switch (Furnas, for example) passes through the L1 and L2 on the outer two poles, and the reversing is done on the inner pole.
Connect T1 to the drum switch terminal which corresponds to L1 and T4 to the drum switch terminal which corresponds to L2.
If the desired voltage is 240, then connect T3 to T2.
If the desired voltage is 120, then connect T3 to T1 and connect T2 to T4.
That connects the run winding, which is not reversed.
Now, for the start winding, assume the wires are labeled T5 and T8 (this varies quite a bit).
For 240 volts, connect one start winding wire to the junction of T3 and T2 (the start winding is always operated on 120 volts, even if the motor is 120/240 volts), and the other wire to a remaining drum switch terminal.
For 120 volts, connect the start winding wires to the remaining drum switch terminals.
05-09-2008, 03:56 PM #6
An example of this setup for 240 volt power shown here:
05-09-2008, 08:51 PM #7
There are at least two different types of 3 pole (6 wire) drum switch connections.
One looks like this:
and some look like this:
Can you either post a picture of the internals of the switch, or tell which type you have. If we know the switch type, and the numbers on the wires in your motor, we can tell you exactly what wires to connect to what terminals.
05-10-2008, 11:40 AM #8
My switch is the first kind you listed. Does the above wiring diagram apply?
05-10-2008, 03:01 PM #9
The wring diagram I put up there uses the most general kind of drum switch, a
three pole, double throw, center off type. All of the contacts really have to be
individually available for that to work.
The short answer, without seeing your swich, is probably not.
05-10-2008, 05:39 PM #10
Now that we know what type of switch you have, we need to know more about your motor. Does it have 4 wires comming out and 2 need to be swapped to reverse? Look at the diagrams below and see if any of them fit your application.
05-11-2008, 01:12 PM #11
This is what I know about the motor...
It is a GE KCR49WN6078 catalog number C1412. Single phase capacitor start/capacitor run. 3/4 horse.
I have wired it with two 110V legs going to the terminal blocks and a ground. The instructions on the motor say to swap the black and red wires to reverse rotation. These two wires are not connected to the terminal blocks where the power wires attach.
Hope that helps,
05-11-2008, 02:19 PM #12
In order to tell you how to coneect the motor to the drum switch, I need to know about the motor and the drum switch. We have completely defined the switch, but not the motor.
How many wires come out of the motor?
How are the wires labeled? (numbers and colors)
Can you post a pic of the motor plate that says how to reverse?
Is the motor dual voltage and if so what voltage are you running?
Can you tell us what wires are connected to what currently? (pics help a lot)
For reference, some standrad drum switch wiring diagrams are shown below, you would need to use the ones in Figure 2 because that is the type of switch you have:
This image shows some connections for a GE KC motor.
01-10-2009, 08:40 PM #13
He was unable to make the drum switch work so I had him stopped because I remembered reading this post some time ago.
My Motor has 6 wires coming from it
It worked like it should hooked up as listed using 110.
drum 1 to t-8 red
drum 2 to t-2 white, t-4 yellow, and white from power source
drum 3 and drum 5 to t-1 blue and T-3 orange
drum 4 to t-5 black
drum 6 to power black
Motor plate says to reverse direction change red t-8 with black t-5
The motor says for high voltage (220)
Line 1 to t-1 and t-8
line 2 to t-2, t-3, t-5
line 3? (I have only 2 lines plus ground) to t-4
Any help would sure be appreciated.
05-14-2009, 05:44 AM #14
01-30-2015, 01:14 PM #15
Hi new member here
i have a furnas switch model 58r327t that is a 3 pole forward and reverse, it is currently wired 220 volts and is on my lathe it is wired to a baldour 1 horse motor. i do not have 220 in my garage or on my work trailer. i am wanting to change the switch to a 110 volt operation. the baldour motor plat says it is a 115/230 volt. there are 6 wires coming out of the motor, t1 t2 t3 t4 t5 t8. From the wire 1 black hot, 1 white, 1 green.
currently wired 220 volts
t1 black connected to Black
t2 red connected to 1 on switch
t3 red connected to 2 on switch
t4 black connected to 6 on switch
t5 white connected to 4 on switch
t8 white connected to 3 on switch
white neutral is connected to 6 on switch
green is connected to frame
i have tried to get this going but nothing seems to work
thank you for your help
01-30-2015, 10:03 PM #16
01-31-2015, 01:09 PM #17
10-16-2015, 07:21 PM #18
Hi I could use a little more help please.
My motor, switch matches everything in this diagram and I can read it too, thank you, but I have one more wire which is P2 that is not in your diagram and i dont know what to do with this P2 any help please, thanks Steve
i looked at this and found that what i just stated is not correct, i have a P1 and P2
i have a P1 and a P2 the others are T2, T3, T4, T5, T8.
Last edited by upsrogue; 10-16-2015 at 07:32 PM. Reason: wrong info
10-16-2015, 09:04 PM #19
If you have a panic situation and hit the drum switch, there is a high probability that you will go through off and to reverse. However the motor will not reverse because the reversing switch only tells it which way to start and the starting winding is disconnected once the motor is running. The lathe will keep running and doing whatever bad thing you tried to stop. Wire the normal control switch for on-off only and put the reversing switch somewhere else. A three phase motor switched to reverse will come to a stop and start up in reverse, giving you time to get the switch off or unwinding you from whatever tangle you have gotten into. Many years ago I took an oath to never again run a machine with a single phase motor and a drum switch.
10-16-2015, 09:55 PM #20
P1 and P2 may be for a thermal protector. Generally that is wanted in series with the entire thing, so it does not allow any power applied if an overheat situation is sensed.
A reasonably handy mechanic can come up with a latch that does not allow flinging the drum switch through to reverse from FWD (or vice versa) without deliberately opening the latch. I agree on the possible hazard, but so far have never had any issue. now I won't, as the machine with the drum switch is 3 phase and will reverse at worst. That might still be bad, incidentally.