Have acquired an old pedestal drill with a British Houston Thompson single phase 1/4hp motor marked KF TD3205 type BS 2408
The motor start capacitor needs replacing but it has no visible markings on it due to several paint coatings !
With capacitor removed the motor will run with a hand start and I can hear what I assume is a centrifugal switch clicking on spin up and spin down.
Any advice on what size capacitor to buy and try ?
IIRC about 2.2uF 450V DC or 250v AC is the approved sort of size. For a sport of one horsepower motor thing.
Go to a company that does motor rewinding as a supplier (Yellow Pages)
- and of course they will be able to tell you anyway.
Rob
There seems to be quit a variation. The one on my 1hp dust collector was
100uF:
bloody eck. Thats biog that is. I did have one lying round on me desk, but it got 'tidied up'.
It isn't that critical., Its just to 'nudge' the motor in the right direction. Too small and the motor wont start or may start backwards..that's all.
A 70 watt burner motor takes a 4 microfarad. Multiplying up a 1/4 hp should be about 187 watts so try as a beginning 11 or 12 microfarad. Make sure any cap you try is rated for mains ac. if it helps you could use 3 of the burner motor caps in parallel. I got mine from Farnell Components a few years ago
IIRC motor caps need to be rated to higher than mains voltage, typ
600v.NT
I would suggest to the OP, that he probably won't go far wrong in choosing a replacement cap of the same size or volume, assuming that the voltage rating is the same of course.
It depends on the capacitor construction, it's age, but generally for motor start capacitors, the value and voltage rating determine the size/volume.
lte$eiq$ snipped-for-privacy@news.albasani.net...
Same physical size/volume doesn't apply as modern capacitors are very much smaller for the same capacitance and voltage rating.
You'll find these in pre-loved (skip grade) central heating circulators (pumps)
In message , YAPH writes
Although the capacitor might well be the reason why the pump is in the skip ...
But not likely - most pumps I come across (or put in!) skips are either surplus to requirements following a boiler swap or have mechanically siezed up.
One might well have thought so except that ...
I used to descale pumps (dozens of the buggers) for a couple of service companies - about 20% were fine other than that the 2.2u cap had died
so , as I said
You were only seeing the non "I just want of get shot of this unrequired pump" collection though - i.e. ones people wanted but thought needed fixing.
Social housing ?
I doubt they got any further than ringing up and saying that the heating had stopped working - t'would be the incompetent fitter from the service company who would take it out
On the motor on my Myford ML7, (I would think that it's a quarter or third HP) the label says -380W, Cap 75-94 Micro Farad. The actual capacitor label says 75 micro Farad, 275V Hope this helps. Cheers Don
Thanks seems a good starting point. I'm not concerned at getting optimum starting performance.
I have one of these motors and it does not appear to have a capacitor on it . It starts but dips the lights in my workshop as it is pulling a few amps on start up is the capacitor internally mounted?
value is not generally critical. IIRC something in the 10-50uF 400V rating or 600V if you can get it.
for 1/4bhp you might get away with even less.
Dozens on ebay.
There are various designs, some with some with a capacitor, some without. Induction motors inherently have poor starting torque.
The ones with a capacitor are marginally better and hence will start against a amall load/run up to speed quicker.
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.