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Default Motor start capacitor - value ?

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 ?
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Default Motor start capacitor - value ?

robert wrote:
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.


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Default Motor start capacitor - value ?

On 10 Sep, 14:44, The Natural Philosopher
wrote:
robert wrote:
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
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Default Motor start capacitor - value ?

John Rumm wrote:
The Natural Philosopher wrote:
robert wrote:
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.


There seems to be quit a variation. The one on my 1hp dust collector was
100uF:

http://www.internode.co.uk/SIP/DSCN5328.JPG

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.

http://www.remco.co.uk/products/capa...stud_mount.htm

i'll be buggered everything from 1 to 100uF seems to be available.
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Default Motor start capacitor - value ?

On 10 Sep, 11:45, robert wrote:
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 ?


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


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Default Motor start capacitor - value ?

On Sep 10, 9:53*pm, cynic wrote:
On 10 Sep, 11:45, robert wrote:

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 ?


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
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Default Motor start capacitor - value ?


"The Natural Philosopher" wrote in message
...
John Rumm wrote:
The Natural Philosopher wrote:
robert wrote:
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.


There seems to be quit a variation. The one on my 1hp dust collector was
100uF:

http://www.internode.co.uk/SIP/DSCN5328.JPG

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.

http://www.remco.co.uk/products/capa...stud_mount.htm

i'll be buggered everything from 1 to 100uF seems to be available.


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.


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Default Motor start capacitor - value ?

On 10 Sep, 22:51, "Fredxx" wrote:
"The Natural Philosopher" wrote in ...



John Rumm wrote:
The Natural Philosopher wrote:
robert wrote:
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.


There seems to be quit a variation. The one on my 1hp dust collector was
100uF:


http://www.internode.co.uk/SIP/DSCN5328.JPG


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.


http://www.remco.co.uk/products/capa...pacitors_stud_...


i'll be buggered everything from 1 to 100uF seems to be available.


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.


Same physical size/volume doesn't apply as modern capacitors are very
much smaller for the same capacitance and voltage rating.
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Default Motor start capacitor - value ?

On Thu, 10 Sep 2009 14:44:09 +0100, The Natural Philosopher wrote:

robert wrote:


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.


You'll find these in pre-loved (skip grade) central heating circulators
(pumps)



--
John Stumbles -- http://yaph.co.uk

What do you mean, talking about it isn't oral sex?
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In message , YAPH
writes
On Thu, 10 Sep 2009 14:44:09 +0100, The Natural Philosopher wrote:

robert wrote:


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.


You'll find these in pre-loved (skip grade) central heating circulators
(pumps)

Although the capacitor might well be the reason why the pump is in the
skip ...

--
geoff


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On Fri, 11 Sep 2009 20:44:46 +0100, geoff wrote:

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.



--
John Stumbles -- http://yaph.co.uk

I am neither for nor against apathy
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In message , YAPH
writes
On Fri, 11 Sep 2009 20:44:46 +0100, geoff wrote:

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
--
geoff
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Default Motor start capacitor - value ?

In message , John
Rumm writes
geoff wrote:
In message , YAPH
writes
On Fri, 11 Sep 2009 20:44:46 +0100, geoff wrote:

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


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

--
geoff
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Default Motor start capacitor - value ?

cynic wrote:
On 10 Sep, 11:45, robert wrote:

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 ?


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

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
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Default Motor start capacitor - value ?



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.


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Default Motor start capacitor - value ?

On Thursday, 10 September 2009 11:45:08 UTC+1, robert wrote:
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 ?


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?
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wrote in message
...
On Thursday, 10 September 2009 11:45:08 UTC+1, robert wrote:
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 ?


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?


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.


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In article ,
"harryagain" writes:

wrote in message
...
On Thursday, 10 September 2009 11:45:08 UTC+1, robert wrote:
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 ?


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?


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.


Just wondering if the OP knows for sure it's a capacitor-start
motor, rather than a capacitor-run motor? The second also gives
a higher running torque, but uses higher grade capacitors.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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On 08/02/14 09:37, Andrew Gabriel wrote:
In article ,
"harryagain" writes:

wrote in message
...
On Thursday, 10 September 2009 11:45:08 UTC+1, robert wrote:
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 ?

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?


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.


Just wondering if the OP knows for sure it's a capacitor-start
motor, rather than a capacitor-run motor? The second also gives
a higher running torque, but uses higher grade capacitors.

He did say something about a centrifugal switch, which suggests start
alone..


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.



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In message , The Natural Philosopher
writes
On 08/02/14 09:37, Andrew Gabriel wrote:
In article ,
"harryagain" writes:

wrote in message
...
On Thursday, 10 September 2009 11:45:08 UTC+1, robert wrote:
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 ?

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?

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.


Just wondering if the OP knows for sure it's a capacitor-start
motor, rather than a capacitor-run motor? The second also gives
a higher running torque, but uses higher grade capacitors.

He did say something about a centrifugal switch, which suggests start
alone..


Umm.. A centrifugal switch could also indicate a simple split phase
motor: where the LR ratio of a secondary winding gives a small phase
change and does not require a capacitor.

Long while since I actually anything about this:-)



--
Tim Lamb
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In message , Tim Lamb
writes
Just wondering if the OP knows for sure it's a capacitor-start
motor, rather than a capacitor-run motor? The second also gives
a higher running torque, but uses higher grade capacitors.

He did say something about a centrifugal switch, which suggests start
alone..


Umm.. A centrifugal switch could also indicate a simple split phase
motor: where the LR ratio of a secondary winding gives a small phase
change and does not require a capacitor.

Long while since I actually anything about this:-)


Oops! ^^knew
--
Tim Lamb
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Default Motor start capacitor - value ?

I have an ancient table saw with a British Houston Thompson single phase 1.0 hp motor V200-220V. Amp 6.9, RPM 1425, BS170 APPD - the cap is gone and I cant read any values. Any ideas on the cap size??
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wrote:
I have an ancient table saw with a British Houston Thompson single phase 1.0 hp motor V200-220V. Amp 6.9, RPM 1425, BS170 APPD - the cap is gone and I cant read any values. Any ideas on the cap size??

This dates from an era when high value capacitors were expensive and
copper windings were cheap. The capacitors were so called ac-
electrolytics and a bit specialised for the application and rarely
marked with a value.

I would not use values from a modern motor as copper is now expensive
and capacitors cheap so the ratios are very different.
Use continuously rated motor run types as these will last longer
If there is any way you can experiment with values, build up from say
10mfd in steps until you get adequate on load starting torque. Be aware
that almost anything will start an unloaded motor. The belts speeding up
from 1425 to respectable saw speeds will impose quite a starting load

If you have pick a value to purchase then maybe 15-20mfd would be a good
guess.

A good source of suitable capacitors to experiment with are the power
factor correction types in old fluorescent lamps which are gradually
being outlawed for the more efficient electric ballast units and so
often found in the scrap.

The other thing to check is if the capacitor has really failed. Other
culprits can be a the centrifugal switches and those early motors are
not usually sealed and dust/dirt can prevent the contacts closing.

Good luck

Bob


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