Starter Coil for 220v 1ph motor

[quintain]

Hi
My 1ph two coil motor is just humming at me at start up.
If I (v.v carefully with a long piece of timber) quickly turn the large saw blade it is driving on my ancient Dominion Universal woodworker, it kicks in.
I attach 2 x pics showing elec' bumph.
BTW the motor is at least 30++yrs old when 2 x were given to me.

Please advise what size etc good quality type at a low cost starter coil I should buy.
I think I will also get a 'Run' coil at the same time.
I also need a 7" (ish) cooling fan 3/8" dia shaft fitting.

Best Regards
Richard (AKA quintain)

 

[Sachakins]

Plenty of capacitors like that on amazon, I had start up problem on bobbin sander, and the good folk here pointed me in right direction. Took a few minutes to find mine no problem. Just matched up voltage and capacitance and size as per original. Started around £7 is.

 

[Old.bodger]

Hi Richard.
Yes, this should be fairly easy to sort. Firstly you are looking for capacitors (years ago called ‘condensers’) not any form of ‘coil’. A good place to start is somewhere like ebay, but for a quality go to RS online.
You need motor start / run capacitors:
1x 160 / 200uf (sometimes expressed as mfd) 220/ 275 volts
1x 15uf rated at 440volts.

The capacitance isn’t absolutely critical ….10% variation isn’t going to cause you problems. Stick to the correct voltage ratings ….the 220/275 might be expressed as a single figure around 240v and the 440 v might be anything 400/ 440….. all are fine. Stick to capacitors rated for motor use. All the other figures on yours are not very impertant unless you are working in the tropics or freezing temps!
You will make your life easier if you can find connections that match yours and also of a close physical size! You may find that yours has single ‘spade connectors on the top….some new ones come with connected dual spades…..this is not an issue. Make sure you know which wire goes to which capacitor ( don’t muddle them up). The capacitors are not polarised so wires can go to either spade on an individual capacitor.
Make sure it all goes back into the housing as these spades are all at full mains voltages!
Happy hunting….at least it’s a fairly cheap fix!

 

[quintain]

Thank you both for your inputs and I now know I should be looking for a capacitor not coil and I further know what size I should be looking for and further that the capacitor is not polarised albeit dangerous at high retained voltage.
I will do an Amazon and ebay search and otherwise for suitable capacitor.
If I can, I will buy from UK source who may also be able to give additional advice.
Again thank you.

 

[quintain]

Hi Richard.
Yes, this should be fairly easy to sort. Firstly you are looking for capacitors (years ago called ‘condensers’) not any form of ‘coil’. A good place to start is somewhere like ebay, but for a quality go to RS online.
You need motor start / run capacitors:
1x 160 / 200uf (sometimes expressed as mfd) 220/ 275 volts
1x 15uf rated at 440volts.

The capacitance isn’t absolutely critical ….10% variation isn’t going to cause you problems. Stick to the correct voltage ratings ….the 220/275 might be expressed as a single figure around 240v and the 440 v might be anything 400/ 440….. all are fine. Stick to capacitors rated for motor use. All the other figures on yours are not very impertant unless you are working in the tropics or freezing temps!
You will make your life easier if you can find connections that match yours and also of a close physical size! You may find that yours has single ‘spade connectors on the top….some new ones come with connected dual spades…..this is not an issue. Make sure you know which wire goes to which capacitor ( don’t muddle them up). The capacitors are not polarised so wires can go to either spade on an individual capacitor.
Make sure it all goes back into the housing as these spades are all at full mains voltages!
Happy hunting….at least it’s a fairly cheap fix!

Hi Old.bodger from another O.B
Do I read you correct, you say:
You need motor start / run capacitors:
START CAP'..1x 160 / 200uf (sometimes expressed as mfd) 220/ 275 volts
RUN CAP' 1x 15uf rated at 440volts.

Why do I need different voltages I.E. (Start) 220+V & (Run) 440v.

 

[Sandyn]

My 1ph two coil motor is just humming at me at start up.

I don't suppose it's humming 'start me up' by the Rolling Stones?

 

[quintain]

Sounds more like "you can make it if you try"

R

 

[Argus]

Why do I need different voltages I.E. (Start) 220+V & (Run) 440v.

The run capacitor with the higher voltage rating is subject to an induction phenomenon in the running motor termed 'back-emf'......... basically, an opposing electromotive force is present during the motor's run condition which can act on the capacitor: the increased voltage tolerance in the capacitor withstands the combined inducted forces and the supply-power to the motor.

Here's a simplified explanation.........happy reading!

https://en.wikipedia.org/wiki/Counter-electromotive_force
It's perfectly normal, but don't skimp on this value in your selection. Over-rated is better than under-rated.

 

[quintain]

Thanks Argus
I now know that 440v is correct and not a (improbable but possible) typo. BUT I wont be reading your link; I tried reading before asking the question and got totally confused.
Again thanks to all.
Richard

 

[guineafowl21]

230V AC mains has a peak voltage of around 330V, hence capacitors need to rated above this. Therefore note that the DC rating should be around 400V (shown as a horizontal line over a dashed line), and the AC rating should be above 230V (shown as ~).

Don’t fit a cap rated for 230V DC or similar for either the run or start side, or you will overvolt it.

 

[quintain]

Hi again at this late stage..

I am again loooking for help.

I fitted a new start capacitor late 2021 and the motor worked but it is again 'humming' at me and not starting.
I am wondering if the centrifugal switch is faulty and perhaps not throwing out the starter capacitor at the right time (i.e. almost immediately)

Would the following centrifugal switch test procedure work:
1. buy and fit a new start capacitor
2. switch on motor to check it is working OK...switch off motor
3. safely remove the leads from the run capacitor
3.1. handle the capacitor safely and position the leads safely
4. start the motor with the hope that it will kick over but switch itself off immediately as a result of the centrifugal switch working correctly

N.B. if the motor continues to run would this indicate the centrifugal switch is not working correctly

The centrifugal switch contacts appear to be free and all seems OK.

The motor details can be seen at the start of this thread

The Starter capacitor I bought can be seen at ..
https://www.ebay.co.uk/itm/184337142390200uf 300uf CD60 250VAC 50/60hz Electric Motor Start Capacitor

 

[guineafowl21]

Your test procedure assumes that the run cap is essential for making it continue to spin, which is not correct. The run cap improves running torque.

If you can get the motor to spin up, let it spin down and you should hear the centrifugal switch click. Beyond that, testing is best done with a multimeter, or by stripping the motor down.

Most likely failure is the new start capacitor. Try a better quality item from someone like RSOnline.