Capacitor again :- (

[Dallas]

I posted a data sheet for a KEMET motor run (20 µF +/-5% 450V
capacitor 25 x 56.5mm and 450v) that would fit inside my rolling
shutters tubular motor. Then I noticed that other data sheets
described it as 45x78mm too large to fit. Turns out, the little
capacitor is "obsolete" replaced by the bigger one. Exact same part
number. (Brilliant KEMET) :- (

I have looked at these data sheets for 20 µF motor run capacitors:
KEMET
Panasonic
Cornell Dubilier
EPCOS/TDK
Dayton
Granger

No luck. Capacitors have increased in size and I can't find smaller
ones. I think voltages are higher and that requires a bigger can?

Ducati Energia has one that is perfect... but natually none in stock in
the USA or anywhere else I can find. (Like trying to finding a rainbow
unicorn.)

So my question is, does anyone know of a capacitor manufacturer that
makes weird/non standard sizes/hard to find capacitors?

................................
What I'm looking for:
I'm replacing a motor run capacitor 20 µF +/-5% 320 volts. Original
can dimensions 35x77mm. (Not including the terminals)

The max diameter I can have is 1.46” or 37.16 mm
The max length I have is 3.8" or 99mm.


--
Dallas

[Ken]

Have you looked at paralleling two 10 µF caps??? You just might be able
to find total dimensions that fit. Not saying you will, but worth
looking at.

[John-Del]

Can you externalize the capacitor?

[Look165]

Regardless to the voltage, since it is greater than or equal 450V,
choose 22µF or 27µF which is more common.
It can be easily found on Radiospares or Farnell.
The size should fit.

[tabb...@gmail.com]

> Can you externalize the capacitor?

probably the only option left. Another core needed for the lead.
I assume the OP has looked on ebay for used caps.


NT

[Fox's Mercantile]

On 5/5/19 11:58 AM, Dallas wrote:
> Capacitors have increased in size and I can't find smaller
> ones.

I had a similar problem. The replacement would not fit in the
stamped steel "dog house."
So the replacement was held in place with a piece of sheet
metal cut to size.

--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com

[Dallas]

Can I toss in a general question?

Is a motor run capacitor always described as a "motor run".

This is the Ducati motor capacitors catalog. On page 15 they have
their Metallized polypropylenefilm capacitors in metallic case... but
they don't say "motor run" anywhere.

http://www.farnell.com/datasheets/24524.pdf

On page 23 they start their Single phase motor starting electrolytic
capacitors. So they specifically call them "motor starting"

Am I wrong to assume that those caps starting on page 15 are motor run
even though they don't specifically say motor run?


--
Dallas

[Dallas]

Look165 wrote:

> Regardless to the voltage, since it is greater than or equal 450V,
> choose 22µF or 27µF which is more common.

Really? I can pick a different µF? My limited research said that a
different µF would cause over heating of the coils and shorten the
life of the motor.

I started with Farnell, no joy.

Radiospares has an amazing filter system!

If I sort by 20µF and motor start I get 5 hits all of which are too
wide for the tube.

--
Dallas

[Dallas]

Ken wrote:

> Have you looked at paralleling two 10 µF caps???

Wow, didn't know you could do that. :- / Interesting.

--
Dallas

[Dallas]

Ken wrote:

> Have you looked at paralleling two 10 µF caps???

--
Dallas

[Dallas]

John-Del wrote:

> Can you externalize the capacitor?

I had that bright idea a couple of days ago... After an hour of
staring at it, the wires run through the 2 limits switches on the way
to the motor. When they reach the limit switch they click open. I
pondered drilling holes in the end cap of the limit switch assembly but
I just don't have enough room to get wires through.

https://bicpentameter.smugmug.com/Other/Misc/n-Cv46BV/i-ZtPwDZR/A

https://bicpentameter.smugmug.com/Other/Misc/n-Cv46BV/i-MDJpcpT/A


The good news is that equivalent replacement motors are available. The
bad news is that 2 of them will cost me $600 bucks. No es bueno.


--
Dallas

[Clifford Heath]

On 6/5/19 2:26 pm, Dallas wrote:
> Look165 wrote:
>
>> Regardless to the voltage, since it is greater than or equal 450V,
>> choose 22µF or 27µF which is more common.
>
> Really? I can pick a different µF? My limited research said that a
> different µF would cause over heating of the coils and shorten the
> life of the motor.

Stay within 40% and it should be fine. Your blind motors don't operate
for long at a time. The run cap effectively creates a third phase, and
increasing or reducing the value moves that phase forward or back a
little, but the tolerance is never tight on these anyhow.

"start" capacitors should get switched out of circuit once the motor is
spinning. They aren't needed and might not be rated for continuous
usage. But it sounds like you need a run capacitor, which would also
work as a start cap.

Clifford Heath

[Rheilly Phoull]

That's what I would do considering they are polypropylene and not
electrolytic.

[Dallas]

Clifford Heath wrote:

> Stay within 40% and it should be fine. Your blind motors don't
> operate for long at a time. The run cap effectively creates a third
> phase, and increasing or reducing the value moves that phase forward
> or back a little, but the tolerance is never tight on these anyhow.

Thank you! Very informative.


--
Dallas

[Dallas]

Rheilly Phoull wrote:

> That's what I would do considering they are polypropylene and not
> electrolytic.

[thumbs up]


--
Dallas

[Dallas]

Rheilly Phoull wrote:

> That's what I would do considering they are polypropylene and not
> electrolytic.

--
Dallas