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Understanding parallel capacitors

In our previous section, we’ve gone deep looking at the introduction of capacitors, today we’ll be discussing the parallel capacitors. You’ll understand the example, formula, calculation, and applications of the parallel capacitors. Remember we said capacitors are components that store electric energy in an electric field. We also learned that different capacitor has their voltage rating, which is the ability for them to store charge. so let dive into what brought us here.

Electrical applications may be designed with as many capacitors as possible. The multiple connections of capacitors act as a single equivalent capacitor with a total capacitance. Well, the amount of capacitance required will determine the numbers of capacitors and how they are connected. The two simple and common types of connections are called series and parallel connections. With these connections, we can easily calculate the total capacitance. Although more complicated connections may include the combinations of the series and parallel.

Read more: Understanding voltage rating of a capacitor

Capacitors in parallel connection

Capacitors are said to be parallel connections when both of their terminals are connected to each terminal of another capacitor. The voltage, Vc connected across all the capacitors that are connected in parallel is the same. So, capacitors in parallel have a common voltage supply across them. for instance,

VC1 = VC2 = VC3 = VAB = 12V

All capacitors with parallel connections have the same voltage across them, such as V1 = V2 = … Vn. where V1 to Vn represent the voltage across each respective capacitor. This voltage is equal to the voltage applied to the parallel connection of the capacitor through the input wires. Although the amount of charge stored in each capacitor is not the same. Also, it depends on the capacitance of each capacitor according to the below formula:

Qn = Cn . Vn

Where Qn is the amount of charge stored on a capacitor, Cn is the capacitance of the capacitor, and Vn is the voltage applied to the complete parallel connection block. The block of the capacitor stored the total amount charge of the capacitor which is represented by Q and is divided between all the capacitors in the circuit. This can be shown as:

Q = Q1 + Q2 + … + Qn

Read more: Understanding the types of capacitors

The above equation of parallel capacitor is used to know the equivalent capacitance for the parallel connection of multiple capacitors:

Ceq =  =  =    +    + … +

Where Ceq is the equivalent capacitance of the parallel connection of capacitors, V is the voltage supplied to the capacitors through the input wires, and Q1 to Qn are the charges stored at each respective capacitor. This is why we have the below equation:

Ceq = C1 + C2 + …. + Cn

The above equation means the equivalent capacitance of the parallel connection of capacitors is equal to the sum of the individual capacitances. Well, the capacitors in parallel can be regarded as a single capacitor, and his plate is equal to the sum of plate areas of individual capacitors.

Read more: Understanding the charge in a capacitor

Calculation of Parallel capacitor

With the explanation of the above equation of parallel capacitor connection. This section will expose you to how to calculate capacitance in parallel connection capacitors. Bear in mind that the values are different from that of the equation. The following circuit shows the capacitors C1, C2 and C3 are all connected in a parallel branch between points A and B as shown in the figure below:

Remember, the total or equivalent capacitance, Ceq in the circuit is equal to the sum of all the individual capacitors added together when the capacitors are connected in parallel. This is due to the top plate of a capacitor, C1 is connected to the top plate of C2 which is connected to that of C3, and so on.

This also occurs to the bottom plates of the capacitors, which makes it three sets of plates touching each other. They are equal to one large single plate which increases the effective plate area in m2.

Because the capacitance, C is related to plate area (C = E(A/d) the capacitance value of the combination will also increase. The total capacitance value of the capacitor connected in parallel is then calculated by adding the plate area together. In another word, the total capacitance is equal to the sum of all the individual capacitances in parallel. This is also how we get the total resistance of series resistors.

Read more: Understanding the dielectric of a capacitor

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Examples of capacitors in parallel

Let take the values of three capacitors so we can calculate the total equivalent circuit capacitance CT. Then we can say:

C1 = C1 + C2 + C3 = 0.1uF + 0.2uF + 0.3uF = 0.6uF

You should know the total capacitance (CT) of any two or more capacitors connected in parallel will be GREATER than the value of the largest capacitor in the circuit. This is because all the values are added together. So, in the above example, CT = 0.6 uF whereas the larges value capacitor in the circuit is 0.3 uF.

 Example 2 of capacitors in parallel

Calculate the capacitance in micro-Farads (μF) of the following capacitors when connected in a parallel combination:

  • Two capacitors each with a capacitance of 47nF
  • One capacitor of 470nF connected in parallel to a capacitor of 1 μF

Read more: Understanding capacitance in AC circuits

Solution

  1. Total capacitance,

CT = C1 + C2 = 47nF + 47nF = 94nF or 0.094 μF

  1. Total capacitance,

CT = C1 + C2 = 470nF + 1 μF

So, CT = 470nF + 1000nF = 1470nF or 1.47 μF

Therefore, the total or equivalent capacitance CT of an electrical circuit containing two or more capacitors in parallel is the sum of all the individual capacitance added together as the effective area of the plates is increased.

Watch the video below to watch the working of capacitors in parallel connection:

Applications

Connecting several capacitors in parallel, the circuit can store more energy because the total or equivalent capacitance is a sum of individual capacitances of all the capacitors. Below are the applications of this capacitance effect:

Read more: Understanding the color code of a capacitor

DC power supplies:

DC power supplies are often used to properly filter the output signal and eliminate the AC ripple. In this method, there is the possibility of using smaller capacitors that have superior ripple characteristics while obtaining higher capacitance values.

Higher capacitance values:

Some applications require capacitance values that are much higher than commercially available capacitors, capacitor banks are used in such situations. One good example is the use of a capacitor bank for power factor correction with inductive loads. Also, these banks can be used in energy storage applications such as in the automobile industry, KERS (Kinetic Energy Recovery System) used for regenerative braking in large vehicles such as trams, and hybrid cars.

Pulsed load:

Capacitor banks are designed to reach high very high capacitance values. So, connecting several ultracapacitors in parallel, capacitances of several tens of kilofarads are feasible. Meanwhile, ultracapacitors are capable of achieving capacitance values of over 2000 farads.

Design restrictions:

When connecting capacitors in parallel, one should know that the maximum rated voltage of a parallel connection of capacitors is only as high as the lowest voltage rating of all the capacitors used in the system. So, if several capacitors of 500V are connected in parallel to a capacitor rated at 100V, the maximum voltage rating of the complete system is only 100V, because the same voltage is applied to all capacitors in the parallel circuit.

Read more: Understanding the charge in a capacitor

Safety:

Due to the amount of energy stored, capacitor banks can be dangerous. And the fact that capacitors can release the stored energy in a very short amount of time. This energy stored can cause serious injuries or damage to electrical wiring and devices if shorted out by accident.

That is all for this article, where the example, formula, calculations, working, and applications of capacitors in parallel connection are being discussed. I hope you got a lot from the reading, if so, kindly share with other students. Thanks for reading, see you next time!

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