Calculation engine operation condenser pump Guinard / ELEM

[Christophe]

I repaired an old pump that had been hanging around for years at home (I finally decided to change the gland gland, see this 2007 about this same pump: https://www.econologie.com/forums/pompe-mult ... t3473.html , I would do another topic on the repair).

My worries of the day: the capacitor seems very tired and I have no idea of ​​the value he has (all black!):





It is an operating capacitor for a brushless motor, here is the connection diagram (I have deliberately omitted the thermal):



I think we can estimate its capacity by a volume measurement? Otherwise what would be the most accurate calculation method? It is a 230V single phase pump from 700W.

A ladle I would say that it is a capacitor of 14μF or 16μF?

But I would prefer to have the precise calculation method ...

[delnoram]

I use the following formula found I do not know where, it was in the 80 years. μf = I / 007222

[elephant]

look a little this:

http://www.volta-electricite.info/artic ... fr&pg=2000

otherwise, do like me: ask google: computation value capacitor startup.

[Christophe]

Ok this is the same formula as delnoram and that corresponds well to my wiring ...

start capacitor value calculation.

Attention this is not a start-up capacitor but of operation (or of a walk capacitor)... see the diagram: the condo will simulate an 3ieme Phase phase ....

It is actually a trick to feed a three-phase winding with single phase ... as explained in the link you just gave

[delnoram]

the site given by elephant, gives a condo of operation, since its role is to simulate the 3eme phase, right?

[Christophe]

Yes quite but obviously elephant did not read the link ...

In short, in my case (cos phi of 0.9) would this be μF = 700 / (230 * 0.9 * 0.07222) = 46 μF approximately?

This corresponds to the line 0.75 kW of this table:



https://www.econologie.com/forums/post173536.html#173536

But question: why my other 800W pump that is wired in the same way has only one 16 μF operating capacitor ??? View the photo: https://www.econologie.com/forums/post287417.html#287417

[delnoram]

Regarding the permanent capacitor it is another story because we cannot rely at all on the power of the motor (especially in addition if the motor does not have a nameplate) because the calculations of the various engineers who design an engine do not always have the same purpose. This is why we can find a capacitor of the same capacity as well on a 1cv motor of one brand as on a 0,5cv of another brand. Why this difference: it is mainly due to the characteristics of the auxiliary winding to which the capacitor is linked, hence the importance of putting a capacitor back to the original value because with a capacitor that is too low the motor does not give its full potential. power and with too strong a capacitor the auxiliary winding heats up excessively and ends up burning. We can not completely trust either the "size" of the old capacitor to put a new one of the same dimensions because depending on the brand it can go from single to double.

http://www.volta-electricite.info/artic ... r&pg=11016

[Christophe]

Ok well, thank you delnoram so if I summarize I am a little blocked because:

a) this is not visibly calculated ...

b) the dimension method also does not work reliably ...

c) the only way would be to measure the capacity of the old capacitor ... but since it is tired (can be HS) it will be difficult too ...

So what to do? Test several capacitors progressively in capacity to be sure not to risk winding the coil?

Oh no, there is another method: I will read the 2th half of the article

[Christophe]

A measurement with a multimeter gives it to (only?) 7 μF

So either he is HS, or I am completely lost!

[Christophe]

Another measurement on a 16µF condo gives only 4.5µF ... but it has already "turned" and is possibly (also) out of order.

The 2 mounted in // give 11.4 µF which is in accordance with the "theory" (7 + 4.5)

Well I'm going to order some capacitors I think ...