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Electric motor needs start capacitor

remzy

Jun 12, 2015
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Hello everyone! I'm new to electric motors and I would need help with one. It doesn't start by itself unless I give it a spin. I think that it's an induction motor. Operatin voltage is 230V. Can you guys tell me where to connect the capacitor in order to make it start spining by itself.
Wires:
1. NOT CONNECTED TO ANYTHING
2. GROUND WIRE
3. 230 V AC
4. 230 V AC20171111_132244.jpg20171111_132259.jpg
 

kellys_eye

Jun 25, 2010
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4,775
Capacitor between 3 and 4. Use a 5μF, 400V capacitor.

Mains hot to 3 (or 4), mains neutral as stated above.

If the motor runs the wrong direction, swap the mains hot from 3 to 4 (or vice versa).

This assumes that the motor windings have been resistively proven to be from 3 to ground and 4 to ground.

The 'unused' wire puzzles me..... sure it's not connected to anything?
 

Minder

Apr 24, 2015
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Check and make sure if there is two separate windings, if there is and the resistance is the same for both, then any one can be used for the start winding, if they are two different values, then use the higher resistance one for the start.
If one is not connected, it could be a second speed.
Report with the winding status/resistance.
M.
 

duke37

Jan 9, 2011
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The motor is labelled 60Hz, you have 50Hz in Bosnia. Has it ever run?
The capacitor reactance varies with frequency.
 

remzy

Jun 12, 2015
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Capacitor between 3 and 4. Use a 5μF, 400V capacitor.

Mains hot to 3 (or 4), mains neutral as stated above.

If the motor runs the wrong direction, swap the mains hot from 3 to 4 (or vice versa).

This assumes that the motor windings have been resistively proven to be from 3 to ground and 4 to ground.

The 'unused' wire puzzles me..... sure it's not connected to anything?
I'm pretty sure. I've tried spining the fan, tought it was a starter winding or centrifugal winding or something like that but i couldn't find any continuity between it and any other wirers. It may be broken at some point. I don't know.
 

Minder

Apr 24, 2015
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What is the resistance between the three?
Sounds like you may have one open.
M.
 
Last edited:

Bluejets

Oct 5, 2014
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Capacitor between 3 and 4. Use a 5μF, 400V capacitor.

Mains hot to 3 (or 4), mains neutral as stated above.

If the motor runs the wrong direction, swap the mains hot from 3 to 4 (or vice versa).

This assumes that the motor windings have been resistively proven to be from 3 to ground and 4 to ground.

The 'unused' wire puzzles me..... sure it's not connected to anything?

I am really curious how you determined that from the photos and lack of info supplied.o_O
Have you see it before?
 

remzy

Jun 12, 2015
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What is the resistance between the three?
Sounds like you may have one open.
M.
I've measured the resistance between wires that have continuity(3,4) and it is aroun 50 to 70 ohm. My meter is not very accurate. I've even tried connecting wire 1, to wires 3 and 4 seperatly while spining the fan to see if it is some sort of centrifugal switch but still nothing. I't might've been a bimetal at some point but it failed. I have no idea.
 
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remzy

Jun 12, 2015
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Is it possible that it would start to spin by itself if the AC frequency was 60 Hz instead of 50?
 

duke37

Jan 9, 2011
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It will need a capacitor to start regardless of frequency.
You will not be able to get a centrifugal switch to disconnect by turning by hand, you need about half motor run speed.

You have a winding between 3 and 4, you need another winding.
What does 1 and 2 connect to?
You say that 2 is ground, do you mean that this is connected to the motor frame?

Lack of any connection to 1 and 2 could be an open circuit winding or centrifugal switch. I would doubt if the complcation of a switch would be justified on such a low powered motor. What was the motor driving? A fan needs very little torque to start, a compressor a lot.
 

remzy

Jun 12, 2015
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It will need a capacitor to start regardless of frequency.
You will not be able to get a centrifugal switch to disconnect by turning by hand, you need about half motor run speed.

You have a winding between 3 and 4, you need another winding.
What does 1 and 2 connect to?
You say that 2 is ground, do you mean that this is connected to the motor frame?

Lack of any connection to 1 and 2 could be an open circuit winding or centrifugal switch. I would doubt if the complcation of a switch would be justified on such a low powered motor. What was the motor driving? A fan needs very little torque to start, a compressor a lot.
It's just a fan from an air condicioning unit I think. the part that goes outside. Yea 2 is earth/ground connected to the frame, which once again leaves wire 1 not connected to anything.
 

Minder

Apr 24, 2015
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It is extremely doubtful that there is a centrifugal switch, a start cap of that nature is usually larger.
It is most likely a PSC motor which has a permanent cap in circuit on one winding, these types of motors usually have two identical winding's that can be alternated for change of direction.
If you do not show resistance for two winding's then it is begining to sound like an open winding.
M.
 

remzy

Jun 12, 2015
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It is extremely doubtful that there is a centrifugal switch, a start cap of that nature is usually larger.
It is most likely a PSC motor which has a permanent cap in circuit on one winding, these types of motors usually have two identical winding's that can be alternated for change of direction.
If you do not show resistance for two winding's then it is begining to sound like an open winding.
M.
Update: I've dissasembled the motor and there is no centrifugal switch not a bimetal switch, only windings. All wires just go into the windings and I cant see where are they connected except the ground wire which is crimped to the motor housing. I connected a meter to wire 1 and phase while the motor was running and got 160V AC reading, same thing happend when I connected it to the neutral, only got 60V AC. Now I'm even more confused how did I get theese reading when there is none connections between it and other wires, only possible option left is that at some point there was a 5th wire so the 1 and 5th were connected together. I'll get a hold of a 5μF capacitor when I can, right now I only found a 9μF one and I'll try to connect it between phase and neutral. What do you guys think?
 

Minder

Apr 24, 2015
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If you Google PSC motor you will see the normal connections.
You would have two windings connect in series with the AC N connected to the centre point, the other AC L1 line would be connected to one other end of one winding, the cap would be connected to L1 and in series with the end of the 2nd winding.
The two series windings are normally equal resistance.
M.
 

remzy

Jun 12, 2015
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Thanks all for all reply's. There is no was this motor is ever going to start spining by itself. I give up. At least it can go any direction depending if I spin it to the left or the right.
 

Jason99

Dec 1, 2017
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Dec 1, 2017
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Hi, here's a question that is not related to this topic. My cassette deck has an AC (120v/60hz) capstan motor, how do I change it to 120v/50hz? Is the problem with the power transformer or the motor itself? And, how does the manufacturer(Sony) make a 120v/50/60hz with the same model, same motor??
 

Minder

Apr 24, 2015
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Usually the transport/pulley/driver mechanism, for e.g. on turntables the pulley is changed for different dia.
They are synchronous motors so the motor runs at whatever the mains freq. is.
M.
 
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