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Discussion Starter · #1 ·
Hi
this is a century electric 2 hp , single phase, dual voltage, inductor motor with centrifugal switch, a starter cap and a run cap. Its wired at 110v but I want to change to 220V which the label diagram says it can be done. The problem is the label is marked coded by color wires but the wires coming out of the motor are numbered not colored. This motor was made in st louis back in 1968 and is going to a powermatic 66 tablesaw. The motor is in good shape and works.
I have looked online extensively for this model of motor and came up with nada. Any help would be most appreciated, thanks.
 

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It looks to me like the 1-2-3-4 wires may have been mislabelled at some point ?
Here is a standard connection diagram, the windings should be on 1-2 and 3-4.


at the bottom of the diagram, it has the standard color codes as well.
 

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It should be as simple as removing the #2 and #3 wire from where they are connected and connecting them together.

You're just changing them from a parallel connection to a series. All other wires stay as is.

Motor manufacturers have sometimes deviated from the standard schemes so I will assume your schematic and wire tag numbers are correct for your motor and it works as given on a 120 volt circuit.

Any numbering scheme deviation usually only affects the start winding wire tags while the run windings usually remain as pair numbers 1-2 and 3-4... therefore with 1-3 on one line and 2-4 on the other line, you have a low voltage connection. Otherwise, with 1 on a line and 2-3 connected together and 4 on the other line, you have a high voltage connection. simple, what?
 

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Discussion Starter · #5 ·
thanks guys, I think I am going to assume the tags are correct as it worked this way with the low voltage wiring and do what surferdude suggests, i will post my results after I am done with the trial run. :vs_OMG:
 

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Discussion Starter · #6 ·
It should be as simple as removing the #2 and #3 wire from where they are connected and connecting them together.

You're just changing them from a parallel connection to a series. All other wires stay as is.

Motor manufacturers have sometimes deviated from the standard schemes so I will assume your schematic and wire tag numbers are correct for your motor and it works as given on a 120 volt circuit.

Any numbering scheme deviation usually only affects the start winding wire tags while the run windings usually remain as pair numbers 1-2 and 3-4... therefore with 1-3 on one line and 2-4 on the other line, you have a low voltage connection. Otherwise, with 1 on a line and 2-3 connected together and 4 on the other line, you have a high voltage connection. simple, what?
Theres just one thing, you said " with 1-3 on one line and 2-4 on the other line you have a low voltage connection." Actually its wired 1-2 on one line and 3-4 on the other line. When I ran a continuity test with my multi tester, I found that 1-3 had continuity and 2-4 had continuity.So which ones to connect? I am confused.
 

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I'm sorry for the confusion... I based the first statement on a standard that I am familiar with and didn't translate it to your wire numbers.

With your numbering system, low voltage is as you have stated... 1-2 on one line and 3-4 on the other.

That doesn't change the high voltage connection so you can go with it as given.
 

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Discussion Starter · #8 ·
Well I am happy to report that the rewiring was successful. I ran the motor out of the tablesaw on the floor and it started up quickly. No heat on the motor or capacitors. I ran it for three minutes and still no heat no smoke it just ran smooth as a whistle. I did notice a slight shift in noise, maybe harmonics, 1 minute into a run. I had it sitting on a yoga mat on concrete. So next time to put it back in the saw and adjust everything. Thank you guys so much for your help. I was really hesitant on taking this on, since it was 220v. Really appreciate it. This forum is great!
Happy DIY'ing.:biggrin2::biggrin2::biggrin2:
 

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But is the rotation correct? :vs_whistle:
 

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It should be as simple as removing the #2 and #3 wire from where they are connected and connecting them together.
Any numbering scheme deviation usually only affects the start winding wire tags while the run windings usually remain as pair numbers 1-2 and 3-4... therefore with 1-3 on one line and 2-4 on the other line, you have a low voltage connection. Otherwise, with 1 on a line and 2-3 connected together and 4 on the other line, you have a high voltage connection. simple, what?
Not quite that simple when the motor has the start cap.
The start winding is a 115V winding, and the Cap rated accordingly.
The wiring needs to be adjusted to the mid-point of the run windings so there is still 115V across the start winding.
I looks like now there is 230V across the start, which will eventually either smoke the start cap or the start winding.


Just quoting you so you get a notification
 

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Discussion Starter · #14 ·
I called and spoke to two different electricians who repair motors, they said its fine I dont need to change the caps. So I wont be doing that. your advice surferdude was right on point! You da man!:vs_cool:
 

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I have looked high and low for something on that specific motor but it's almost like it never existed. That said, I think we need to cover all possible pitfalls and test to be sure the start winding is receiving the proper voltage. It will certainly run as is, but if the start winding isn't wired properly, it can/will fry itself in time.

So... here's what you need to do. It just involves moving one wire, the one tagged "8" from where it is to the 3-2 junction. That is based on several other motor diagrams that I have found. Granted the main winding tags on most other motors don't agree with yours, it doesn't change the fact that the start winding should be on the mid-point of any high voltage series hookup, as @Shadow99 astutely pointed out. Some manufacturers prewire that at the internal board but since you apparently have the start winding wires (5 & 8) at the exterior motor junction box, it follows that you have to make that selection on your particular motor.

I'll attach a motor diagram that looks like is correct for your motor high voltage wiring scheme based on the way you laid it out. It's a little blurred but the low voltage diagram is on the left and the high on the right. As you can see, your tags don't agree with the low voltage scheme shown.
 

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If that correction causes the motor rotation to be incorrect, just swap the 5 and 8 wire connects.
 

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Take it loose from where it is and put it with the 2-3 junction. That will make it look like the diagram on the label of the motor I posted.
 

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Discussion Starter · #19 ·
what is the risk if this is wrong? its working right now im just hesitant.....but so far you have been right...reassure me...
 

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Discussion Starter · #20 ·
my wiring doesnt agree with the hi either in your label that you kindly provided,
so now This is what i got under the 230v hi scheme:

1-5 (white line) 2-3 wired together 4,8,7 (black line)
 
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