What is a capacitor bank used for?

3e (Electrical Energy Efficiency FZE) has 20 years in power factor correction. We would like to share our expertise with informative articles to educate others.


In this article, we will explain and share our knowledge about capacitor banks.


On the internet, you can find many articles, but the target of our article is to make the explanation
simple and smooth understanding of capacitor bank functions.


In every project there is an electrical panel, let say 2500 A, from this panel as a client in normal conditions
you may not be able to use more than 70 to 75% of the available current or Amp, due to the efficiency
factor, hence come to the role of the capacitor bank.

Engineer testing capacitor bank for harmonics

What is a capacitor bank?

A capacitor bank is an electrical panel, made of an enclosure,

In a normal electrical panel there is :
The complex power S, P( active power ) and Q reactive power, called triangles of powers.


In addition, there is the useful current and non-useful current.


In each panel like the one we have described above there:
S (complex power or total power )= V*A
P (active power ) which is the KW that the normal public knows or hear about it, where the useful
current comes.
Q(reactive power ) that generate the non-useful current.

So In other words, if you have an electrical panel 2500 A without capacitor bank and you measure the PF
or efficiency factor, you may get around 0.7 or 70% efficiency.

What is efficiency factor?


It means that as a client you can benefit from 2500 x 0.7 =1750 A from your total panel capacity.

This is the useful current and the other 750 A would be non-useful current. We call it the Ping-Pong
current.

Why do we call it PING PONG current?

Because this current will comes from the source to the load and rotate back through neutral current but the customer or client cannot benefit from it, in his factory or company or production line.

So the good current 1750A generates the Power P then give us the good power (Kilo Watt) then generates the bill
in kWH as a consumer, to pay for the utility.


P=VAPF

Q is generated from the non-useful current (or ping pong current.)


From the above explanation, we can conclude why we have to use a capacitor bank.

Engineers test capacitor bank

Does capacitor bank improve power factor?


The capacitor bank improves the PF (power factor) or efficiency factor to 0.9 or 0.95 so as client or factory we can
benefit from the maximum current generated by the panel

(in a future article we will discuss why utility enforces capacitor bank installation)


So the job of the capacitor bank is to improve the efficiency by increasing the Good current, hence P(active power) and reducing the non-useful current, hence reducing Q (reactive power).


The capacitor bank does that by using capacitors installed inside.


The capacitor bank rating will be in kVAR which will be designed in the form of steps that can be 4, 6, 12, 14
steps and each step rating can be from 2.5 up to 30 and 50 KVAR.


The regulator or electronic item installed in the capacitor bank, connect or disconnect steps based on
the load, in order to maintain the targeted PF (power factor), an expected target which is recommended to be
between 0.9 to 0.95.

Do you have any questions or ideas? Contact us at hello@3edubai.com.

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