The first, did not tell about sufficient reason, for example charge conversation law, after capacitance establishs ties, the n that connects a capacitance is identical.

 

The 2nd, our result is to want, after two capacitance establish ties, cent is pressed, these two cent pressing do not exceed rated voltage. So we need to calculate cent pressing, contrast next rated voltage.

 

Make simple calculation first: Capacitance paralell connection

 

 

Formulary: C and 1 ＋ of ＝ C C 2, compression value is C 1, c the lesser U=Min{U1 in the compression value of 2, u2} .

 

For example: C 1:20uf, 250v; C2:30uf, 450v, criterion C and =C1+C2=20uf+30uf=50uf, compression is worth U=Min{250v, 450v}=250v.

 

Value of compression value option is little that, next redo falls the forehead can.

 

Capacitance series connection:

 

 

Formulary: 1/C strings together =1/C1+1/C2, namely C strings together ＝ C 1*C2/(C1+C2) , compression is worth U ＝ Min{C2*U2/C1, u1} +Min{C1*U1/C2, u2} , the compression that compression is worth and is not equal to two capacitance is worth the sum.

 

For example: C 1:20uf, 250v; C2:30uf, 250v. Establish ties capacitance good computation: C strings together 20*30/(20+30)=12uf of ＝ of ＝ C 1*C2/(C1+C2) ,

 

Attention: Compression is worth U=250v+250v=500v (×) , this kind of computation is wrong.

 

Simple analysis: Because two capacitance size is distinct, capacitive reactance is different, cent pressing is different also, if 500v voltage brings to bear on after series connection, can have depress of a cent at 250v, can a cent pressing exceeds 250v, exceeded its compression value, compression of reason series connection wants under 500v.

 

Correct and formulary: Compression is worth U ＝ Min{C2*U2/C1, u1} +Min{C1*U1/C2, u2}

 

=Min{30*250/20, 250}+Min{20*250/30, 250}=416.7V

 

At this moment: The cent of capacitance C1 is pressed for Min{30*250/20, 250}= Min{375, 250}=250v

 

The cent of capacitance C2 is pressed for Min{20*250/30, 250}= Min{166.7, 250}=116.7v

 

Later development is derivation process:

 

 

Afore-mentioned it is the series connection that does not have polarity capacitance, shunt-wound capacity and compression computation. And to having polarity electroanalysis capacitance, not be simple apply mechanically afore-mentioned computational methods, and the circumstance in having 4:

 

1, electroanalysis capacitance same polarity is shunt-wound: The shunt-wound capacity of capacitance and compression cost formula are right now applicable still.

 

 

2, electroanalysis capacitance reversal sex is shunt-wound: Because always be put in a capacitance to be in anyhow,press reversely right now fall condition, cannot use.

 

 

3, electroanalysis series connection of capacitance same polarity: The series connection capacity of capacitance and compression cost formula are right now applicable still.

 

 

4, electroanalysis capacitance reversal sex strings together:

 

Using capacitance watch to measure is right, cannot using below the circumstance of big electric current, high-power, or life is very brief. Because a capacitance is in,accept position instead, leakage current can increase gradually, electric plate can be corroded gradually, can such capacitance go? And as a result of existence a capacitance is received instead, its compression value is 0, the value also is equal to the compression after series connection to be worth to the compression of the capacitance that put through at most, cannot compression of applicable series connection is formulary, more cannot simple addition.

 

 

If, we do not have sufficient high capacity without polarity capacitance, also do not have the has polarity electric capacity of enough compression.

 

 

Use next graphs to improve, can add life, this is reasonable. Can add life, but total meeting has a capacitance to be in press reversely fall, although voltage is not tall (diode is pressed fall) , but electroanalysis can capacitance do not have an influence? We need to evaluate capacitance the life of retrorse time folds caustic.

 

And the compression that did not forget compression is not two capacitance is worth the sum, and can take lesser compression cost only.