Pillar drill motor

[Bsmith]

Some time ago the 1/2 HP motor on my pillar drill burned out. I replaced it with a 1 HP motor just because it was one I had handy.
Motor is fine but slow to start especially with cold weather when the belts are stiff. I often need to slacken the belts, start the motor then tighten the belts before drilling.
The motor start cap is 400v, 30uF.
I am wondering if I get a start cap with a higher uF if that will sort my problem please?
Does the cap need to be 400v on a 240v machine?

 

[Kayos]

400v is the max voltage, other than size it doesn’t make a difference to the value

 

[Bsmith]

Ok thank you. Could you give an indication of what size of cap I would need to look for please? That's if you agree with me that a cap with a higher uF will kick the motor into action faster.

 

[angellonewolf]

cant actualy give an answer but see link

http://www.dnr.louisiana.gov/assets/TAD/education/ECEP/hvac/d/d.htm

 

[WorkshopChris]

Might be worth looking at the cable size a 1hp motor on something like a drilling machine should start almost instantly.
If the cable was already undersized for the half hp motor its now double although probably only around 4 or 5 amps running but a 1hp will very briefly pull around 30aA on start up.
Volt drop could be a issue.

 

[knighty]

^^ as above

but also, can you turn it easily by hand ?

nothing is stuck/catching/slowing it down etc. ? - could be why the old motor burnt out

 

[Maker]

Ok thank you. Could you give an indication of what size of cap I would need to look for please? That's if you agree with me that a cap with a higher uF will kick the motor into action faster.

I don't think it will, all it's there for is to create a phase offset in the start winding, changing its value will change the time constant and therefore the phase angle, all it'll really do is make the motor run a bit hotter and burn out again sooner.

 

[Bsmith]

Might be worth looking at the cable size a 1hp motor on something like a drilling machine should start almost instantly.
If the cable was already undersized for the half hp motor its now double although probably only around 4 or 5 amps running but a 1hp will very briefly pull around 30aA on start up.
Volt drop could be a issue.

I changed the cables along with the motor, supply cable to switch and switch to motor with what I'm sure is adequate, but as with previous motor it's got a 13A plug on the end with 13A fuse.

^^ as above

but also, can you turn it easily by hand ?

nothing is stuck/catching/slowing it down etc. ? - could be why the old motor burnt out

Pulleys turn freely without belts on them.

I don't think it will, all it's there for is to create a phase offset in the start winding, changing its value will change the time constant and therefore the phase angle, all it'll really do is make the motor run a bit hotter and burn out again sooner.

Before I saw this post I borrowed a 100uF cap off a different motor, which fired the drill up instantly but it vibrated like hell, found a 8uf cap which ran the motor about half speed with no belts on. Plate on the motor says 30uF cap.

 

[WorkshopChris]

I changed the cables along with the motor, supply cable to switch and switch to motor with what I'm sure is adequate, but as with previous motor it's got a 13A plug on the end with 13A fuse.

OK good so volt drop isn't a issue. If everything mechanically feels ok and all spins freely then might be worth a look inside the motor to see if it looks like its got hot at some point and has cooked the start winding,could be shorted turns.

 

[penfold]

Wire the 8 and the 30 in parallel and report back; 100 is much too big though.

 

[knighty]

are you sure the cap on the motor is ok?

I'd buy a new one and swap it first (they're cheap enough)

 

[Bsmith]

Wire the 8 and the 30 in parallel and report back; 100 is much too big though.

Sorry friend, I don't know what the 8 and the 30 are or how to wire parallel.

are you sure the cap on the motor is ok?

I'd buy a new one and swap it first (they're cheap enough)

My thoughts too last night so I looked them up on the bay and ordered one, then realised it is in China so will have to wait 2 - 3 weeks for it to arrive. No hardship though, drill has been like this since mid last year.

 

[Memmeddu]

Some time ago the 1/2 HP motor on my pillar drill burned out. I replaced it with a 1 HP motor just because it was one I had handy.
Motor is fine but slow to start especially with cold weather when the belts are stiff. I often need to slacken the belts, start the motor then tighten the belts before drilling.
The motor start cap is 400v, 30uF.
I am wondering if I get a start cap with a higher uF if that will sort my problem please?
Does the cap need to be 400v on a 240v machine?

You can try to put a start capacitor between the phase and the Neutral (not in the contatcs that modulate star or delta windings)

 

[Bsmith]

New start capacitor solved the problem. Thanks all.