Formula for delta star in capacitors

In summary, using the delta-star conversion formula for capacitors, you can find out the equivalent capacitance by taking the AC impedance of the capacitor and applying the formula.
  • #1
avistein
48
1

Homework Statement



How to find out the equivalent capacitance using delta star conversion?


Homework Equations



Delta star conversion formula of capacitors

The Attempt at a Solution



Using the formula of resistors but not coming.What is the formula of delta star in capacitors?
 
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  • #2
The slow way to do it is from first principles.

The quick way is to use the AC impedance of a capacitor, which is ##\displaystyle \frac{1}{j\omega C}##, which can be treated like a resistance, then apply the delta-star conversion formula to it and see what you end up with. Remember to convert the final impedance you get back to a capacitance by reversing the formula.
 
  • #3
The delta-star transformations work for more than simple resistance - they work for any impedance.

So just convert the capacitances to impedances ... and use the formulas for resistors.

Then convert the impedances back into capacitances.
 
  • #4
Curious3141 said:
The slow way to do it is from first principles.

The quick way is to use the AC impedance of a capacitor, which is ##\displaystyle \frac{1}{j\omega C}##, which can be treated like a resistance, then apply the delta-star conversion formula to it and see what you end up with. Remember to convert the final impedance you get back to a capacitance by reversing the formula.

Hi Curious3141,
quick run down... C1 across b and c, C2 across c and a, C3 across a and b.
I'm trying to derive the formula for Ca in terms of C1, C2 and C3.
If these capacitors were resistances the formula would be Ra=(R2R3/R1+R2+R3) (I think ?)
there for if capacitors.. 1/ωCa=(1/ωC2*1/ωC3)/(1/ωC1+1/ωC2+1/ωC3). (??)
How do I convert this back to capacitance so I just have Ca=...?
 
  • #5
Greg Arnald said:
there for if capacitors.. 1/ωCa=(1/ωC2*1/ωC3)/(1/ωC1+1/ωC2+1/ωC3). (??)
How do I convert this back to capacitance so I just have Ca=...?
Looks like it's just a bit of algebra. Logically, you know that ω should ultimately play no role in the capacitance values you obtain, so it should cancel out along the way. Might as well just eliminate it from the start (or choose a convenient working frequency such as ω = 1). That may make things less cluttered looking.
 

Related to Formula for delta star in capacitors

What is the formula for delta star in capacitors?

The formula for delta star in capacitors is: Cdelta = C1 + C2 + C3, where C1, C2, and C3 are the capacitance values of the three capacitors in the delta configuration.

How is the delta star formula different from the series and parallel formulas?

The delta star formula is different because it takes into account the connection of three capacitors in a triangular shape, while the series and parallel formulas only consider two capacitors connected in a line or side by side.

Can the delta star formula be used for any number of capacitors?

Yes, the delta star formula can be extended to any number of capacitors in a delta configuration. The general formula is: Cdelta = C1 + C2 + ... + Cn, where C1, C2, ..., Cn are the capacitance values of each capacitor.

What are the advantages of using a delta configuration for capacitors?

The advantages of using a delta configuration for capacitors include: a higher capacitance value compared to a single capacitor, better stability, and the ability to handle higher voltages.

Can the delta star formula be used for capacitors with different values?

Yes, the delta star formula can be used for capacitors with different values. However, the resulting capacitance will be different from the individual capacitance values, and it may be necessary to use a conversion factor to accurately calculate the total capacitance.

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