higher value start capacitor

B

bristan

Guest
I have replaced a 12 uf +/-10% start capacitor in a pump motor with a 15 uf
+/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read elsewhere
that it will just slightly increase the strarting torque and should not be a
problem. The motor is working ok now. Would there be any adverse effects?
.....Opinions ?
 
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor with a 15 uf
+/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read elsewhere
that it will just slightly increase the strarting torque and should not be
a problem. The motor is working ok now. Would there be any adverse
effects? ....Opinions ?
Click to expand...
Shouldn't be a problem.
 
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor with a 15 uf
+/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read elsewhere
that it will just slightly increase the strarting torque and should not be
a problem. The motor is working ok now. Would there be any adverse
effects? ....Opinions ?

Shouldn't be a problem.
Click to expand...

If it's a start cap with centrifugal switch it should be ok but if it's
a run cap it can overspeed and heat the motor. Pumps usually don't need
the extra torque of a start winding so it may be in the circuit all the
time like some of the pumps I've seen.
 
Ian Macmillan wrote:
Overspeed??

All the best
Ian Macmillan
Click to expand...

try playing around with the cap values on a cap run motor
the speed will vary and the motor runs much hotter at higher
speeds.
 
"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor with a
15 uf
+/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read
elsewhere
that it will just slightly increase the strarting torque and should not
be
a problem. The motor is working ok now. Would there be any adverse
effects? ....Opinions ?

Shouldn't be a problem.




If it's a start cap with centrifugal switch it should be ok but if it's
a run cap it can overspeed and heat the motor. Pumps usually don't need
the extra torque of a start winding so it may be in the circuit all the
time like some of the pumps I've seen.
Click to expand...
Overspeed??

All the best
Ian Macmillan
 
bristan Inscribed thus:

I have replaced a 12 uf +/-10% start capacitor in a pump motor with a
15 uf +/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read
elsewhere that it will just slightly increase the strarting torque and
should not be a problem. The motor is working ok now. Would there be
any adverse effects? ....Opinions ?
Click to expand...
It will be just fine. Leave it be...

--
Best Regards:
Baron.
 
"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor with a 15
uf +/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read
elsewhere that it will just slightly increase the strarting torque and
should not be a problem. The motor is working ok now. Would there be any
adverse effects? ....Opinions ?

Shouldn't be a problem.


If it's a start cap with centrifugal switch it should be ok but if it's
a run cap it can overspeed and heat the motor. Pumps usually don't need
the extra torque of a start winding so it may be in the circuit all the
time like some of the pumps I've seen.
Click to expand...
It is a davey xp900h and looking up the specs says it is P.S.C. start.
ie permanent split capacitor which according to Wiki , is in the circuit all
the time .
and is a start and run capacitor.no centrifugal switch
other specs... 2 pole, 0.8kw, 2850 rpm
I haven't noticed it running any hotter. It may be a bit faster. The cap I
pulled out of it was measuring only 6.7uf tho marked 12uf.
Pump is not new and gets a lot of work stopping and starting as a household
water supply.
Pump was failing to start sometimes even tho the pressure switch was on. now
ok with new cap.
I might try and pick up a 12 uf as it is no trouble to change and only $12.
regards
 
On Thu, 15 Jul 2010 15:48:18 +1000, "bristan" <none@none.com> wrote:

"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor with a 15
uf +/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read
elsewhere that it will just slightly increase the strarting torque and
should not be a problem. The motor is working ok now. Would there be any
adverse effects? ....Opinions ?

Shouldn't be a problem.


If it's a start cap with centrifugal switch it should be ok but if it's
a run cap it can overspeed and heat the motor. Pumps usually don't need
the extra torque of a start winding so it may be in the circuit all the
time like some of the pumps I've seen.

It is a davey xp900h and looking up the specs says it is P.S.C. start.
ie permanent split capacitor which according to Wiki , is in the circuit all
the time .
and is a start and run capacitor.no centrifugal switch
other specs... 2 pole, 0.8kw, 2850 rpm
I haven't noticed it running any hotter. It may be a bit faster. The cap I
pulled out of it was measuring only 6.7uf tho marked 12uf.
Pump is not new and gets a lot of work stopping and starting as a household
water supply.
Pump was failing to start sometimes even tho the pressure switch was on. now
ok with new cap.
I might try and pick up a 12 uf as it is no trouble to change and only $12.
Click to expand...
In that case you might want to pop in the right value before summer, just
so the motor is run to spec., especially if the pump runs for long periods.

The 15uF is letting through more current to the start winding, gonna
come out as heat, perhaps a little more work done. Cost you a little
more in power. I doubt it will kill the motor unless there's already
a heat problem.

Grant.
 
bristan Inscribed thus:

"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor with
a 15 uf +/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read
elsewhere that it will just slightly increase the strarting torque
and should not be a problem. The motor is working ok now. Would
there be any adverse effects? ....Opinions ?

Shouldn't be a problem.


If it's a start cap with centrifugal switch it should be ok but if
it's a run cap it can overspeed and heat the motor. Pumps usually
don't need the extra torque of a start winding so it may be in the
circuit all the time like some of the pumps I've seen.

It is a davey xp900h and looking up the specs says it is P.S.C.
start. ie permanent split capacitor which according to Wiki , is in
the circuit all the time .
and is a start and run capacitor.no centrifugal switch
other specs... 2 pole, 0.8kw, 2850 rpm
I haven't noticed it running any hotter. It may be a bit faster. The
cap I pulled out of it was measuring only 6.7uf tho marked 12uf.
Pump is not new and gets a lot of work stopping and starting as a
household water supply.
Pump was failing to start sometimes even tho the pressure switch was
on. now ok with new cap.
I might try and pick up a 12 uf as it is no trouble to change and only
$12. regards
Click to expand...
I wouldn't waste my money !
Look at it this way. Assume that the original cap was at the top of its
spec, ie 12uf + 10% = 13.5uf and assume that the 15uf is at the bottom
of its spec, ie 15uf - 10% = 13.5uf.
It ain't worth messing.

--
Best Regards:
Baron.
 
On Thu, 15 Jul 2010 19:39:18 +0100, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:

bristan Inscribed thus:


"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor with
a 15 uf +/- 5% cap. The supplier did not have a 12 uf in stock
Should I order a 12uf or leave the 15uf in place ? I have read
elsewhere that it will just slightly increase the strarting torque
and should not be a problem. The motor is working ok now. Would
there be any adverse effects? ....Opinions ?

Shouldn't be a problem.


If it's a start cap with centrifugal switch it should be ok but if
it's a run cap it can overspeed and heat the motor. Pumps usually
don't need the extra torque of a start winding so it may be in the
circuit all the time like some of the pumps I've seen.

It is a davey xp900h and looking up the specs says it is P.S.C.
start. ie permanent split capacitor which according to Wiki , is in
the circuit all the time .
and is a start and run capacitor.no centrifugal switch
other specs... 2 pole, 0.8kw, 2850 rpm
I haven't noticed it running any hotter. It may be a bit faster. The
cap I pulled out of it was measuring only 6.7uf tho marked 12uf.
Pump is not new and gets a lot of work stopping and starting as a
household water supply.
Pump was failing to start sometimes even tho the pressure switch was
on. now ok with new cap.
I might try and pick up a 12 uf as it is no trouble to change and only
$12. regards

I wouldn't waste my money !
Look at it this way. Assume that the original cap was at the top of its
spec, ie 12uf + 10% = 13.5uf and assume that the 15uf is at the bottom
of its spec, ie 15uf - 10% = 13.5uf.
It ain't worth messing.
Click to expand...
It's just as valid to consider the pessimal worst case too, if the
pump's start winding cooks this summer, OP is out of pocket a fair
bit more than a $12 cap.

Grant.
 
Grant Inscribed thus:

On Thu, 15 Jul 2010 19:39:18 +0100, Baron
baron.nospam@linuxmaniac.nospam.net> wrote:

bristan Inscribed thus:


"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor
with a 15 uf +/- 5% cap. The supplier did not have a 12 uf in
stock
Should I order a 12uf or leave the 15uf in place ? I have read
elsewhere that it will just slightly increase the strarting
torque and should not be a problem. The motor is working ok now.
Would there be any adverse effects? ....Opinions ?

Shouldn't be a problem.


If it's a start cap with centrifugal switch it should be ok but if
it's a run cap it can overspeed and heat the motor. Pumps usually
don't need the extra torque of a start winding so it may be in the
circuit all the time like some of the pumps I've seen.

It is a davey xp900h and looking up the specs says it is P.S.C.
start. ie permanent split capacitor which according to Wiki , is in
the circuit all the time .
and is a start and run capacitor.no centrifugal switch
other specs... 2 pole, 0.8kw, 2850 rpm
I haven't noticed it running any hotter. It may be a bit faster. The
cap I pulled out of it was measuring only 6.7uf tho marked 12uf.
Pump is not new and gets a lot of work stopping and starting as a
household water supply.
Pump was failing to start sometimes even tho the pressure switch was
on. now ok with new cap.
I might try and pick up a 12 uf as it is no trouble to change and
only $12. regards

I wouldn't waste my money !
Look at it this way. Assume that the original cap was at the top of
its spec, ie 12uf + 10% = 13.5uf and assume that the 15uf is at the
bottom of its spec, ie 15uf - 10% = 13.5uf.
It ain't worth messing.

It's just as valid to consider the pessimal worst case too,
Click to expand...
I agree, I would bet that its low rather than high, but only by
measuring the caps actual value would confirm that.

if the
pump's start winding cooks this summer, OP is out of pocket a fair
bit more than a $12 cap.

Grant.
Click to expand...
--
Best Regards:
Baron.
 
"Baron" <baron.nospam@linuxmaniac.nospam.net> wrote in message
news:i1qivg$gpm$1@news.eternal-september.org...
Grant Inscribed thus:

On Thu, 15 Jul 2010 19:39:18 +0100, Baron
baron.nospam@linuxmaniac.nospam.net> wrote:

bristan Inscribed thus:


"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor
with a 15 uf +/- 5% cap. The supplier did not have a 12 uf in
stock
Should I order a 12uf or leave the 15uf in place ? I have read
elsewhere that it will just slightly increase the strarting
torque and should not be a problem. The motor is working ok now.
Would there be any adverse effects? ....Opinions ?

Shouldn't be a problem.


If it's a start cap with centrifugal switch it should be ok but if
it's a run cap it can overspeed and heat the motor. Pumps usually
don't need the extra torque of a start winding so it may be in the
circuit all the time like some of the pumps I've seen.

It is a davey xp900h and looking up the specs says it is P.S.C.
start. ie permanent split capacitor which according to Wiki , is in
the circuit all the time .
and is a start and run capacitor.no centrifugal switch
other specs... 2 pole, 0.8kw, 2850 rpm
I haven't noticed it running any hotter. It may be a bit faster. The
cap I pulled out of it was measuring only 6.7uf tho marked 12uf.
Pump is not new and gets a lot of work stopping and starting as a
household water supply.
Pump was failing to start sometimes even tho the pressure switch was
on. now ok with new cap.
I might try and pick up a 12 uf as it is no trouble to change and
only $12. regards

I wouldn't waste my money !
Look at it this way. Assume that the original cap was at the top of
its spec, ie 12uf + 10% = 13.5uf and assume that the 15uf is at the
bottom of its spec, ie 15uf - 10% = 13.5uf.
It ain't worth messing.

It's just as valid to consider the pessimal worst case too,

I agree, I would bet that its low rather than high, but only by
measuring the caps actual value would confirm that.
Click to expand...
measured it at 15.13uf
there has been a very noticeable increase in water pressure since replacing
the old cap which had deteriorated to only 6.7uf.
Pump seems to run more quietly also. Slighly warm to touch after running for
a while in winter temps.



if the
pump's start winding cooks this summer, OP is out of pocket a fair
bit more than a $12 cap.

Grant.

--
Best Regards:
Baron.
Click to expand...
 
bristan Inscribed thus:

"Baron" <baron.nospam@linuxmaniac.nospam.net> wrote in message
news:i1qivg$gpm$1@news.eternal-september.org...
Grant Inscribed thus:

On Thu, 15 Jul 2010 19:39:18 +0100, Baron
baron.nospam@linuxmaniac.nospam.net> wrote:

bristan Inscribed thus:


"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor
with a 15 uf +/- 5% cap. The supplier did not have a 12 uf in
stock
Should I order a 12uf or leave the 15uf in place ? I have
read elsewhere that it will just slightly increase the
strarting torque and should not be a problem. The motor is
working ok now. Would there be any adverse effects?
....Opinions ?

Shouldn't be a problem.


If it's a start cap with centrifugal switch it should be ok but
if it's a run cap it can overspeed and heat the motor. Pumps
usually don't need the extra torque of a start winding so it may
be in the circuit all the time like some of the pumps I've seen.

It is a davey xp900h and looking up the specs says it is P.S.C.
start. ie permanent split capacitor which according to Wiki , is
in the circuit all the time .
and is a start and run capacitor.no centrifugal switch
other specs... 2 pole, 0.8kw, 2850 rpm
I haven't noticed it running any hotter. It may be a bit faster.
The cap I pulled out of it was measuring only 6.7uf tho marked
12uf. Pump is not new and gets a lot of work stopping and starting
as a household water supply.
Pump was failing to start sometimes even tho the pressure switch
was on. now ok with new cap.
I might try and pick up a 12 uf as it is no trouble to change and
only $12. regards

I wouldn't waste my money !
Look at it this way. Assume that the original cap was at the top of
its spec, ie 12uf + 10% = 13.5uf and assume that the 15uf is at the
bottom of its spec, ie 15uf - 10% = 13.5uf.
It ain't worth messing.

It's just as valid to consider the pessimal worst case too,

I agree, I would bet that its low rather than high, but only by
measuring the caps actual value would confirm that.


measured it at 15.13uf
Click to expand...
Mmm. I'm slightly surprised its high.

there has been a very noticeable increase in water pressure since
replacing the old cap which had deteriorated to only 6.7uf.
Pump seems to run more quietly also. Slighly warm to touch after
running for a while in winter temps.
Click to expand...
That is the behavior I would expect with the new cap. There is more
current flowing through the windings and therefore more torque to drive
the impellor, so the motor isn't slowing down under load like it did
with the duff (old) cap. There may be an over temperature cutout in
the motor windings to protect it from stall conditions.

--
Best Regards:
Baron.
 
On Sat, 17 Jul 2010 17:58:27 +0100, Baron <baron.nospam@linuxmaniac.nospam.net> wrote:

bristan Inscribed thus:


"Baron" <baron.nospam@linuxmaniac.nospam.net> wrote in message
news:i1qivg$gpm$1@news.eternal-september.org...
Grant Inscribed thus:

On Thu, 15 Jul 2010 19:39:18 +0100, Baron
baron.nospam@linuxmaniac.nospam.net> wrote:

bristan Inscribed thus:


"Mark Harriss" <billy@blartco.co.uk> wrote in message
news:A9OdnUAUY9EL5KDRnZ2dnUVZ8kmdnZ2d@westnet.com.au...
Noodnik wrote:
"bristan" <none@none.com> wrote in message
news:4c3cf38e$1@dnews.tpgi.com.au...
I have replaced a 12 uf +/-10% start capacitor in a pump motor
with a 15 uf +/- 5% cap. The supplier did not have a 12 uf in
stock
Should I order a 12uf or leave the 15uf in place ? I have
read elsewhere that it will just slightly increase the
strarting torque and should not be a problem. The motor is
working ok now. Would there be any adverse effects?
....Opinions ?

Shouldn't be a problem.


If it's a start cap with centrifugal switch it should be ok but
if it's a run cap it can overspeed and heat the motor. Pumps
usually don't need the extra torque of a start winding so it may
be in the circuit all the time like some of the pumps I've seen.

It is a davey xp900h and looking up the specs says it is P.S.C.
start. ie permanent split capacitor which according to Wiki , is
in the circuit all the time .
and is a start and run capacitor.no centrifugal switch
other specs... 2 pole, 0.8kw, 2850 rpm
I haven't noticed it running any hotter. It may be a bit faster.
The cap I pulled out of it was measuring only 6.7uf tho marked
12uf. Pump is not new and gets a lot of work stopping and starting
as a household water supply.
Pump was failing to start sometimes even tho the pressure switch
was on. now ok with new cap.
I might try and pick up a 12 uf as it is no trouble to change and
only $12. regards

I wouldn't waste my money !
Look at it this way. Assume that the original cap was at the top of
its spec, ie 12uf + 10% = 13.5uf and assume that the 15uf is at the
bottom of its spec, ie 15uf - 10% = 13.5uf.
It ain't worth messing.

It's just as valid to consider the pessimal worst case too,

I agree, I would bet that its low rather than high, but only by
measuring the caps actual value would confirm that.


measured it at 15.13uf

Mmm. I'm slightly surprised its high.
Click to expand...
For a brand new 5% cap? I'm not ;) Is there an industry norm of
supplying caps at bottom of error range?
there has been a very noticeable increase in water pressure since
replacing the old cap which had deteriorated to only 6.7uf.
Pump seems to run more quietly also. Slighly warm to touch after
running for a while in winter temps.

That is the behavior I would expect with the new cap. There is more
current flowing through the windings and therefore more torque to drive
the impellor, so the motor isn't slowing down under load like it did
with the duff (old) cap. There may be an over temperature cutout in
the motor windings to protect it from stall conditions.
Click to expand...
One would expect so. But constant higher temp operation may shorten
life... Then again, it might keep the pump warmer and drier for less
corrosion?

Grant.
 
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