Question about what capacitor size and type for 600w 230v motor

Thread Starter

AshPant

Joined Sep 12, 2019
9
Im having some issues replacing a capacitor on a blower motor for my kids jumping castle. the original one was so cooked i could not read the specs on it.

I looked up the run capacitor size for the motor size and tried that (12uf capacitor for a 240v 600-720w motor)
it worked but the castle is not inflating properly.

I then put in a 15uf capacitor hoping to increase the fan speed but it was hardly inflating at all

I have a 10uf capacitor on order. Am I doing something wrong? is the capacitor type critical?

the company that makes them are no help at all they just keep trying to sell me a new blower.

any Ideas?

thanks,
Ashley
 

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MaxHeadRoom

Joined Jul 18, 2013
21,191
I would have expected a Universal motor for a blower in this application, if you confirm it is a PSC induction motor then is the new cap still getting warm/hot in operation?
Max.
 

MisterBill2

Joined Jan 23, 2018
6,685
I have seen these jumping things and they would never use a universal motor for the blower. If the TS still has the failed capacitor then we van look at a picture of it and get some grasp of the size. That willprovide a clue as to the power handling capabilities of the capacitor. And I suggest giving the motor a close sniff test (Power OFF) to see if perhaps the motor is also failed. And, if possible, post a photo of the motor, showing side and back views, and a view of whatever side the power cord enters on. Many folks can recognize motors very well. And then we can see if it somehow might be a universal motor.
 

MisterBill2

Joined Jan 23, 2018
6,685
A brush type of motor is noisier and it wears much faster, and in addition, it has more starting torque, which is not wanted for a high-rotating mass centrifugal blower. There is less wear if it starts more gently. Besides all of that, a brush type motor will need service during it's lifetime and for devices like the jumping toys they do not want them to ever need blower motor service. At least that is the case for the larger rental ones. Also, brush type motors cost more, and that really matters with toys.
 

bob2

Joined Jun 15, 2019
191
Before dealing with the motor, you need to deal with the capacitor. Measure its parameters with any cheap multimeter. Why did the TS decide that a 12uF capacitor is needed and not 25uF? In general, there is a certain sequence in finding the causes of malfunctions.
 

MisterBill2

Joined Jan 23, 2018
6,685
Before dealing with the motor, you need to deal with the capacitor. Measure its parameters with any cheap multimeter. Why did the TS decide that a 12uF capacitor is needed and not 25uF? In general, there is a certain sequence in finding the causes of malfunctions.
It will be a real challenge to measure any electrical parameters of a fried capacitor that the TS needs to replace. And another easy thing would be to connect both capacitors in parallel and see how the motor runs.
There needs to be an additional specification tag someplace on the motor giving RPM and some part number. That yellow tag is not it. Also, if the TS has access to a multimeter and could provide thr resistance measurements between whatever connection wires are present that can be useful as well. A 600 watt motor would be about 3/4 HP with normal efficiency, and for a blower it may be a 2-pole type running 3000 RPM, nominal, on 50 HZ.
So once again, can we see pictures of both the actual motor and the failed capacitor.
 
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MaxHeadRoom

Joined Jul 18, 2013
21,191
A brush type of motor is noisier and it wears much faster, and in addition, it has more starting torque, which is not wanted for a high-rotating mass centrifugal blower. There is less wear if it starts more gently. Besides all of that, a brush type motor will need service during it's lifetime and for devices like the jumping toys they do not want them to ever need blower motor service. At least that is the case for the larger rental ones. Also, brush type motors cost more, and that really matters with toys.
Just about all vacuum motors (blowers) I have ever come across have Universal motors, maximum air flow.
The exception is the mechanical pump for vacuum tables etc.
The typical centrifugal (vacuum) air blowers do not typically have a high impelar mass .
Max.
 

bob2

Joined Jun 15, 2019
191
It would be interesting to see a photo of a toasted capacitor, but that doesn't happen often.
With regard to film capacitors.
The capacitor may lose its capacitance, losses (D, ESR) may increase, there may be an internal breakage or an internal short circuit.
 

MaxHeadRoom

Joined Jul 18, 2013
21,191
It would be interesting to see a photo of a toasted capacitor, but that doesn't happen often.
With regard to film capacitors.
The capacitor may lose its capacitance, losses (D, ESR) may increase, there may be an internal breakage or an internal short circuit.
Many pieces of equipment such as this that come out of China, notoriously have poor quality in the motor-run capacitor area, it is wise to obtain/replace with a quality replacement such as made by CDE etc.
It is a common complaint among the small machine importers from China. :(
Max.
 

bob2

Joined Jun 15, 2019
191
Naturally, much depends on the quality of the components used.
But much also depends on the operating conditions, temperature conditions, stable supply voltage, etc.
I had a case when the capacitance of the film capacitor of the motor decreased by half, from 6uF to 3uF.
 

MaxHeadRoom

Joined Jul 18, 2013
21,191
Naturally, much depends on the quality of the components used.
But much also depends on the operating conditions, temperature conditions, stable supply voltage, etc.
I had a case when the capacitance of the film capacitor of the motor decreased by half, from 6uF to 3uF.
The oil filled paper versions I use from CDE do not suffer that fate.
Max.
 

MisterBill2

Joined Jan 23, 2018
6,685
The problem in this case is not knowing the value of the capacitor to use as a replacement. are you telling us that new capacitors are failed? THAT does not seem reasonable. And I stil stand with my suggestion of trying both in parallel to see if that works. And seriously, giving the motor the sniff test to see if it may be burned up as well as the capacitor.
There is a whole lot about this that we have not been told. And without a look at the failed capacitor we will not know. It may be that we can learn something from seeing it that the TS does not see.
 

MisterBill2

Joined Jan 23, 2018
6,685
Putting the caps in parallel is a good idea, in series would provide a lower value,
More capacitance is what is needed. 12+15 =27, closer to 30 and that should work a bit better.
 
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