motor control.

Thread Starter

mcash2000

Joined May 12, 2024
18
Hi All.
i am trying to help a friend install single phase motor onto a forward reverse roll bending machine via 2 foot pedals.
he had problems with original motor a chucked in bin and ordered a new one trouble was there is now drawings for me to follow.
motor is twin capacitor run/star it also has a electronic centrifugal switch with no numbering.
question : is there anybody on here that has good motor control knowledge that can help?
regards
Mark
 

LesJones

Joined Jan 8, 2017
4,227
Your first step is to identify the ends of the main and auxiliary widings. The main winding will be connected to the supply (Via the switching circuit. The auxiliary winding in series with the run capacitor (The smaller value of the two capacitors.) will be connected to the supply via polarity reversing contacts in the switching circuit. The start capacitor in series with the centrifugal switch in the motor will be connected in parallel with the run capacitor.
As you have not provided any information about the motor connection box and a schematic of the foot pedals and the contactors in the control circuit this is all the help I can provide. What evidence do you have that the original fault was caused by a faulty motor and not the control circuit.

Les.
 

Thread Starter

mcash2000

Joined May 12, 2024
18
Your first step is to identify the ends of the main and auxiliary widings. The main winding will be connected to the supply (Via the switching circuit. The auxiliary winding in series with the run capacitor (The smaller value of the two capacitors.) will be connected to the supply via polarity reversing contacts in the switching circuit. The start capacitor in series with the centrifugal switch in the motor will be connected in parallel with the run capacitor.
As you have not provided any information about the motor connection box and a schematic of the foot pedals and the contactors in the control circuit this is all the help I can provide. What evidence do you have that the original fault was caused by a faulty motor and not the control circuit.

Les.
Hi Les
Many thanks for the reply much appreciated.
I know the run and start windings and have mapped out the control panel wiring. As for the old motor which went to tip it was all done long before I went to have a look for him as his son who is house spark didn’t really have a clue and he just left all wires all over the place. The motor he got has electronic CF switch and I have got the correct wires now for that. I am out at the moment but will return in an hour and will send you the layout as from memory out from control panel is 4 wires w2 - u2 - u1 -v1
 

Thread Starter

mcash2000

Joined May 12, 2024
18
I have never used an electronic CF switch but imagine they are functionally the same as a normal centrifugal switch.

Les.
I have never seen one before but yes they do i have tested once i got the wiring layout have run the more one way with both caps connected so know the CF switch working
i just need a little help with a wiring diagram that will run of the foot pedals.
4 wires coming of cp are W2 which is live, U2 which is L/N V1 which is N and U1 which is L/N I'm guessing its where they switch positions.
now when the new motor was on machine they left two winds connected together W1 and U1 to turn CW and you would need to change U1 with U2 to go CCW.
would i be right to say W1 and U1 should not be connected together as cp would sort that bit.?
 

LesJones

Joined Jan 8, 2017
4,227
Although the motor runs when connected as in your diagram it is possible that it does not have the start and run capacitors connected correctly. there seem to be 4 connections to the motor windings which is what I would expect. Two for the ends of the main winding and two for the ends of the aux winding. Can you do resistance tests on the motor to identify the winding and post the resistance of the two windings. these resistance values will be quite low . (ohms or tens of ohms depending on the size of the motor.) I would have expected the new motor to come with some information. This may be stuck to the inside of the motor connection box cover. I imagine the electronic centrifugal switch works by sensing the current in the main winding to decide when to break the circuit to the start capacitor. Can you post the information on this switch.

Les.
 

Thread Starter

mcash2000

Joined May 12, 2024
18
Although the motor runs when connected as in your diagram it is possible that it does not have the start and run capacitors connected correctly. there seem to be 4 connections to the motor windings which is what I would expect. Two for the ends of the main winding and two for the ends of the aux winding. Can you do resistance tests on the motor to identify the winding and post the resistance of the two windings. these resistance values will be quite low . (ohms or tens of ohms depending on the size of the motor.) I would have expected the new motor to come with some information. This may be stuck to the inside of the motor connection box cover. I imagine the electronic centrifugal switch works by sensing the current in the main winding to decide when to break the circuit to the start capacitor. Can you post the information on this switch.

Les.
W1 and W2 = 4.5 Ohms
U1 and U2 = 2.3ohms
W1 and U1 linked measured at W2 and U2 = 6.5 ohms
as for the motor wiring well see picture attached
 

Attachments

LesJones

Joined Jan 8, 2017
4,227
Looking at the motor diagram jn post #9 it looks like the labels U1 and U2 are the labels on the wires that come out from the ends of the main winding.
I think your diagram in post #10 is basically correct. The two wires you show going to the switch will be the red and blue wires from the switch. (This will be a set of contacts.) You will need to connect the white and black wires to the U1 and U2 to provide power to the electronic centrifugal switch.
I looked on line for informations about electronic centrifugal switches and found that the way I assuned that they worked was wrong. They do not sense the current in the main winding. They just close the contacts for a short period of time when power is first applied. I don't know if you can break the links between the upper and lower two left hand terminals or if you will need to use an extra connector block to connect to the U1 and U2 ends of the main winding.

Les.
 

MaxHeadRoom

Joined Jul 18, 2013
28,825
The only kind of start winding cap SW, other than centrifugal type I have come across, is the external current relay version, it is closed by the high initial cap charge current and opens after the up to speed time.
 

LowQCab

Joined Nov 6, 2012
4,294
My initial take on this situation is that a Cap-Start / Cap-Run Motor
is usually designed for high-Operating-Efficiency.
But the application sounds like it's very abusive to the Motor,
with constant directional changes / Starts, Stops.

If this is actually the case,
I don't think that that particular Motor-Configuration is going to last very long in this application,
especially the Start-Capacitor, which is very likely to overheat and pop.
.
.
.
 

Thread Starter

mcash2000

Joined May 12, 2024
18
My initial take on this situation is that a Cap-Start / Cap-Run Motor
is usually designed for high-Operating-Efficiency.
But the application sounds like it's very abusive to the Motor,
with constant directional changes / Starts, Stops.

If this is actually the case,
I don't think that that particular Motor-Configuration is going to last very long in this application,
especially the Start-Capacitor, which is very likely to overheat and pop.
.
.
.
It is the motor that the company supplied as a replacement. When asked for drawing they said find an electrician with motor experience. Go figure. Lack of support once motor sold.
 

MaxHeadRoom

Joined Jul 18, 2013
28,825
With reference to the mention of start capacitors, ensure it is not of Chinese origin, they have a history of failure, use a N.A. brand, preferably!
Start motor rated.
 

Thread Starter

mcash2000

Joined May 12, 2024
18
Hi All.
Right i have come to the end of me trying as i don't know if its the electronic centrifugal switch or i am missing something.
i have done a drawing of what the motor came with i.e how it runs with just l and neutral connected.
i have also done on with what connections i have.
please step in if you can work out how the connections should go to make forward reverse possible.
the switching is via foot pedals and the outgoing cables from panel are W2 V1 U1 U2 as shown on drawings.

Any Help Greatly Appreciated.
 

Attachments

LesJones

Joined Jan 8, 2017
4,227
From your drawing in post # 10 can you confirm that the polarity of terminals U1 and U2 (Marked with L/N) reverses when the direction switch is changed from forward to reverse ? I would use 4 lamps connected as follows to confirm this.
Lamp A to W2 and V1
Lamp B to U1 and U2
Lamp C to V1 and U1
Lamp D to W2 and U2
With the direction switch in one direction all 4 lamps should light.
With the switch in the other direction only lamps A & B should light.
As we have NO INFORMATION on the electronic centrifugal switch I suggest using a manual switch to switch in the start capacitor foe a second or so when power is first applied. When we have got it to work in this configuration we will sty to sort out the electronic swtch. (I suspect that with NO mechanical load on the motor it will start without the start capacitor connected.)
If you post some pictures of the electronic centrifugal switch someone may recognise it and we might find the manufacturers website. (I have never seen one of these switches.)


Les.
 

Thread Starter

mcash2000

Joined May 12, 2024
18
From your drawing in post # 10 can you confirm that the polarity of terminals U1 and U2 (Marked with L/N) reverses when the direction switch is changed from forward to reverse ? I would use 4 lamps connected as follows to confirm this.
Lamp A to W2 and V1
Lamp B to U1 and U2
Lamp C to V1 and U1
Lamp D to W2 and U2
With the direction switch in one direction all 4 lamps should light.
With the switch in the other direction only lamps A & B should light.
As we have NO INFORMATION on the electronic centrifugal switch I suggest using a manual switch to switch in the start capacitor foe a second or so when power is first applied. When we have got it to work in this configuration we will sty to sort out the electronic swtch. (I suspect that with NO mechanical load on the motor it will start without the start capacitor connected.)
If you post some pictures of the electronic centrifugal switch someone may recognise it and we might find the manufacturers website. (I have never seen one of these switches.)


Les.
Thanks for the reply Les I will double check later just to confirm switching.
Once I have confirmed I will write back.
As for the centrifugal switch they are a thing found on the net all donate thing.
 

Thread Starter

mcash2000

Joined May 12, 2024
18
From your drawing in post # 10 can you confirm that the polarity of terminals U1 and U2 (Marked with L/N) reverses when the direction switch is changed from forward to reverse ? I would use 4 lamps connected as follows to confirm this.
Lamp A to W2 and V1
Lamp B to U1 and U2
Lamp C to V1 and U1
Lamp D to W2 and U2
With the direction switch in one direction all 4 lamps should light.
With the switch in the other direction only lamps A & B should light.
As we have NO INFORMATION on the electronic centrifugal switch I suggest using a manual switch to switch in the start capacitor foe a second or so when power is first applied. When we have got it to work in this configuration we will sty to sort out the electronic swtch. (I suspect that with NO mechanical load on the motor it will start without the start capacitor connected.)
If you post some pictures of the electronic centrifugal switch someone may recognise it and we might find the manufacturers website. (I have never seen one of these switches.)


Les.
P.s could you draw up a diagram to show connections using what I have sent ?
 
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