Single phase motors with 3 wires into motor HElP

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SUMMARY

The discussion centers on troubleshooting a single-phase motor with a capacitor used in a woodworking saw. The motor has three wires: black, brown, and blue, with unclear connections after the original switch was removed. Participants recommend using a multimeter to identify the start and run windings, emphasizing that the capacitor does not have a negative terminal due to alternating current. The conversation highlights the importance of correctly wiring the motor to avoid blowing fuses and suggests that the configuration of the external wiring may be the source of the problem.

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Scottyb
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Hey

I was wondering if anyone could help me, I have a single phase motor with a single capacitor,on a woodworking saw, which the switch broke, it was sprung loaded, so I guess a start run switch. It's for a friend and he took the switch off without marking the terminals, I can't find another switch like it anywhere, I have tried making my own start switch using a n/o push button, but I keep blowing fuses there are three wires going in a black brown blue, the blue is connected to a thin brown wire going straight into the motor, the brown is connected to capacitor a thicker red wire, the black goes to another black wire and also a thinner brown, if anyone can help it would make me so happy!

Thanks scotty
 
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Scottyb said:
Hey

I was wondering if anyone could help me, I have a single phase motor with a single capacitor,on a woodworking saw, which the switch broke, it was sprung loaded, so I guess a start run switch. It's for a friend and he took the switch off without marking the terminals, I can't find another switch like it anywhere, I have tried making my own start switch using a n/o push button, but I keep blowing fuses there are three wires going in a black brown blue, the blue is connected to a thin brown wire going straight into the motor, the brown is connected to capacitor a thicker red wire, the black goes to another black wire and also a thinner brown, if anyone can help it would make me so happy!

Thanks scotty

Here is a picture if anyone can help! thanks
 

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is that photo looking at the old broken switch?

here's a washing machine motor i recently decoded with an ohm-meter.

WashingMachineMotorWiring2.jpg


Yours will be similar but with no "slow" winding. What i called "fast" is the run winding for you. Sadly there seems no systematic color code.

Start winding will be a few ohms, run winding will be fewer.

Isolate start winding.
Apply voltage across run winding and motor will hum but not start.
Give shaft a spin either direction and it'll run that way.
It won't hurt the motor to hum a few seconds but don't let it go on long.
That'll tell you whether the motor is going to be useable.

We'll go from there.

old jim
 
Am I right in saying the neutral will be connected to the negative of the capacitor? Thanks very much for replying really appreciate it, it has become a personel how to myself to get it working again! Thanks again scott
 
Scottyb said:
Am I right in saying the neutral will be connected to the negative of the capacitor? Thanks very much for replying really appreciate it, it has become a personel how to myself to get it working again! Thanks again scott

A capacitor for AC use doesn't have a "negative" terminal as the volts alternate as much one way as the other. There may be an 'earthy' side , though, and that is sometimes indicated on the case. That would be connected to the neutral.
 
Ah ok right, I was told find the negative of the capacitor and that would indicate where my neutral of the incoming poeer to the motor would be.
 
I think that was 'shorthand' for "Earthy end".
Point is, can you actually identify the right terminal?
 
there are three wires going in a black brown blue,

do those wires disappear into the motor or are those the three wires from spring loaded switch?


the blue is connected to a thin brown wire going straight into the motor, the brown is connected to capacitor a thicker red wire, the black goes to another black wire and also a thinner brown, if anyone can help it would make me so happy!

i can't tell which is which in your picture.
is the capacitor shown in your picture or is it external?
Does it have a value stamped on it?

What are those brown and blue wires coming in upper left, the ones that somebody added after the top was removed?


Do you have a multimeter with ohms scale on it? RX1 would be best, or a digital.

I couldn't decipher this phrase
the brown is connected to capacitor a thicker red wire
by a thicker red wire perhaps?
and a thicker red wire perhaps?

perhaps you could use PAINT or something and annotate the picture.

Here's my best guess at what you have.

scottysmotor1.png



The print came out a bit small

as you see i made some assumptions about the capacitor
see if this works

[apply power between center and rightmost terminals
measure voltage between leftmost and center
if motor starts you should read voltage there only after motor has reached speed.]

if it works my assumptions were good.
If they were and those two mystery wires are how you applied power, you put it across the centrifugal start switch and may have burnt its contacts. But it'd explain blowing fuse.

it has become a personel how to myself to get it working again!


I too feel obliged to rescue old machines. it's usually an iterative process, though .

Good thing i can't afford an airplane. I Love old Bonanzas but they are a money pit..


old jim
 
hey i have revised the drawing to show what the parts are, hope this clears it up a little? I am still unsure why i would have 2 lives coming from a signle phase supply, i have never seen this before, it would beeen soo bloody good if there was a drawing on the inderside of the plate! it must be the few I've seen withouht this! thanks for help again!

Scott
 

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  • #10
hope this clears it up a little? I am still unsure why i would have 2 lives coming from a signle phase supply,

that's some help but i too find one too many wires. And i still can't see whether they land on the three terminals or disappear into motor's innards.

next is it blowing fuses in this configuration?

How'd it get in this configuration, in other words are we looking for external wiring trouble or internal motor trouble?

Are you sure there's no brushes in the motor?

Have you a multimeter?
 
  • #11
That's how the motor was wired in this configuration it worked, so definitely external problems, so its the configuration of the external, yeah I'm pretty sure there's no brushes,

Thanks
 
  • #12
perhaps we need to look at the switch, then.

Have you a photo of it?
 

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