Single phase motors with 3 wires into motor HElP

In summary, the capacitor is external and has a value stamped on it. The brown and blue wires coming in upper left are the wires from the spring loaded switch. The motor will hum but not start when the voltage is applied between the leftmost and center terminals. If it works, my assumptions were good.
  • #1
Scottyb
6
0
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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  • #2
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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  • #3
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
 
  • #4
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
 
  • #5
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.
 
  • #6
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.
 
  • #7
I think that was 'shorthand' for "Earthy end".
Point is, can you actually identify the right terminal?
 
  • #8
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
 
  • #9
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?
 

1. How do I determine which wire is which in a single phase motor with 3 wires?

The three wires in a single phase motor are typically labeled as T1, T2, and T3. To determine which wire is which, you can use a multimeter to measure the resistance between each wire. The wire with the highest resistance is typically T1, the wire with the second highest resistance is T2, and the wire with the lowest resistance is T3.

2. What is the purpose of the third wire in a single phase motor?

The third wire in a single phase motor is typically a ground wire. It is used to provide a safe path for any excess electricity to flow to the ground, protecting the motor from damage and preventing electrical shock.

3. Can I connect a single phase motor with 3 wires to a regular household outlet?

No, a single phase motor with 3 wires requires a special type of outlet called a single phase outlet. These outlets have four prongs instead of the standard two prongs found in household outlets. It is important to always use the correct outlet to avoid damaging the motor or causing an electrical hazard.

4. What is the difference between a single phase motor with 3 wires and a single phase motor with 2 wires?

A single phase motor with 3 wires has an additional wire for grounding, while a single phase motor with 2 wires does not. This means that the 3-wire motor is safer and more protected from electrical hazards, but it also requires a special outlet and may be slightly more complex to wire.

5. Can I reverse the direction of a single phase motor with 3 wires?

Yes, it is possible to reverse the direction of a single phase motor with 3 wires. This can be done by swapping the connections of T1 and T2, or by using a reverse switch if the motor has one. However, it is important to consult the motor's manual or a professional for guidance, as incorrect wiring can damage the motor.

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