Quizzes & Puzzles1 min ago
electric motor
4 Answers
Hi All,
I have just bought a second hand cement mixer. The 250 v motor has been disconnected from the capactor/condenser. It is being fed from a direct mains feed, so the consequence is that you have to turn the drum by hand to get it to run from the motor, and as soon as you put cement into it it slows and stops.
question is: should the capacitior be wired in series with one of the incoming leads, I.E. one of the incoming power conductors to the capacitor, out of the other terminal and on to one of the motor terminals, or is it connected across the pair? live and neutral at the motor?
thanks for all your replies, I will stand well back when I switch on!!!!
regards,
doris thundercrack.
I have just bought a second hand cement mixer. The 250 v motor has been disconnected from the capactor/condenser. It is being fed from a direct mains feed, so the consequence is that you have to turn the drum by hand to get it to run from the motor, and as soon as you put cement into it it slows and stops.
question is: should the capacitior be wired in series with one of the incoming leads, I.E. one of the incoming power conductors to the capacitor, out of the other terminal and on to one of the motor terminals, or is it connected across the pair? live and neutral at the motor?
thanks for all your replies, I will stand well back when I switch on!!!!
regards,
doris thundercrack.
Answers
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Difficult to advise without seeing it but it is probably a split phase capacitor start induction motor.
There would be two sets of windings. Sometimes four terminations are brought out. Others have the windings connected together inside so only three terminations.
The main winding is connected directly to the power. The other (start winding) has a centrifugally operated switch and is wired in series with the cap. You can sometimes hear the switch cut out as the motor comes up to speed.
The start winding can be determined by its higher resistance. The direction is selected by reversing the start winding. The main winding polarity doesn't matter.
The three terminal style sometimes has the start winding connected to a centre tap of the main winding. The direction can be selected by connecting the other end to either the active or neutral.
The less common split phase capacitor run motor doesn't have a switch and the capacitor is in circuit all the time. The fact that your motor is lacking in torque could suggest that yours is one of these.
Or maybe the motor is faulty. Somebody has disconnected the cap for a reason I expect.
There would be two sets of windings. Sometimes four terminations are brought out. Others have the windings connected together inside so only three terminations.
The main winding is connected directly to the power. The other (start winding) has a centrifugally operated switch and is wired in series with the cap. You can sometimes hear the switch cut out as the motor comes up to speed.
The start winding can be determined by its higher resistance. The direction is selected by reversing the start winding. The main winding polarity doesn't matter.
The three terminal style sometimes has the start winding connected to a centre tap of the main winding. The direction can be selected by connecting the other end to either the active or neutral.
The less common split phase capacitor run motor doesn't have a switch and the capacitor is in circuit all the time. The fact that your motor is lacking in torque could suggest that yours is one of these.
Or maybe the motor is faulty. Somebody has disconnected the cap for a reason I expect.
You�ve asked this question before � beso has given a comprehensive answer here.
Besides the motor being faulty, it could be the capacitor. The capacitance value in this application is not normally critical, providing that the voltage rating is equal to or greater, and the capacitance is within �50% +100% of the original value � the motor should run. It is important that the capacitor is non-polarised (otherwise it will go bang).
Besides the motor being faulty, it could be the capacitor. The capacitance value in this application is not normally critical, providing that the voltage rating is equal to or greater, and the capacitance is within �50% +100% of the original value � the motor should run. It is important that the capacitor is non-polarised (otherwise it will go bang).
Hi,
Thanks for the advice. Idid ask this before, about 8 months ago, and just got round to trying to use the mixer. I was hoping someone would say something like "connect the capacitior in series with the neutral", or " connect it across the two terminals". It looks like I will have to take it off and go and see a motor rewind company and let them see it.
If it had been three phase it would have been simple, star -delta, leading and lagging phases etc. etc.
But thanks again for the answers, very comprehensive.
regards,
doris.
Thanks for the advice. Idid ask this before, about 8 months ago, and just got round to trying to use the mixer. I was hoping someone would say something like "connect the capacitior in series with the neutral", or " connect it across the two terminals". It looks like I will have to take it off and go and see a motor rewind company and let them see it.
If it had been three phase it would have been simple, star -delta, leading and lagging phases etc. etc.
But thanks again for the answers, very comprehensive.
regards,
doris.
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