elec motor capasitors

Hi all, 2 questions ........

a, have to replace a 45mf capasitor but can only find 40 or 50.....would the 50mf be ok....(it's for a constant run wood planer machine).......

b, 2.4kw Crompton Parkinson motor fitted to a pillar drill...what is the correct capasitor size (the original has been replaced with a plastic coated capasitor that is unreadable) to start the drill I just spin the pulley by hand (naughty, I know)....

any suggestions for a supplier other than the bay of flea's........

ta clogs

50 mfd should be fine, make sure it's rated for motor use at >400V ac.

I'll check the cap on the Brook motor I've got.

Well I checked and my motor plate says "100 mfd" which seems large for a 1/2 HP. Then I notice that you say 2.4 kW  - on a pillar drill? That's something north of 3 hp!! Surely not single phase capacitor start? Do you mean 240V?

Edited By John Haine on 15/03/2018 14:46:16

I was going to suggest RS Components but noticed they sell them in boxes of 36 for over £500!

Try Farnell. (I believe it's the same company as RS, but the former specialise in commercial sales. In the good old days you needed to be registered at Companies House, own Industrial premises, and have a computerised Billing/Invoice/Accounts system before RS would sell you anything. They've mellowed a fair bit but even so they still don't encourage penny pinching amateurs!)

Dave

Edited By SillyOldDuffer on 15/03/2018 14:53:24

Whats wrong with the 'bay'? these work fine : **LINK**

and in the size you require

Regards

Lofty

Edited By FMES on 15/03/2018 15:01:13

It wasn't quite that bad! My dad had an account with RS for his telly-hire & electricals shop back in the 70s/80s.

RS /= Farnell - Farnell are competitors to RS.

You are thinking of Farnell and CPC with the latter targeting the retail market.

Are you sure the fault is the capacitor and not the centrifugal switch ? If you disconnect one of the capacitor wires and then measure the resistance between the terminal that the wire was connected to and the terminal where the other capacitor iwire is still connected to you should measure a resistance value equal to the start winding and run winding in series. (Expect less than about 20 ohms.) This goes via the centrifugal switch so if you get a high resistance reading then it is probably the centrifugal switch that is open circuit. (It could also be the start winding but that is unlikely.) As you mention that the old capacitor was marked 45 mF it is probably quite old. mF used to mean microfarads but now mF means millifarads. uF ia now used for microfarads. CPC (Another branch of Farnell. )is another possible source of supply. They have free delivery on orders over £5.00 so thay may work out cheaper than Farnell.

Les.

I use Amazon quite a lot, very good service and often free post.

Edited By V8Eng on 15/03/2018 17:01:03

It's a fair cop guv!

I do appreciate how much the Internet has opened up shopping though. In the past many big names only did wholesale, probably because the cost of setting up accounts for small purchases was more trouble than it was worth. Now they're queuing up to take my pennies on-line!

Dave

just to add, the plate on the Crompton motor is actally tin foil......and almost unreadable.......

will look again in the morning, better light and the eye's work better.......

the only number I could read was 2.4 so guessed at Kw......ooops......

not really into this new way of sizing motors........

promise to try harder.........ta clogs

2.4 amps at 250 v is 600watts so a third to half HP , about right for a pillar drill.