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Low-Voltage Power Distribution and Installation Technology

How to calculate capacitor requirement.

Thread Starter: PISCEAN 2010   Started: 2/13/2011 5:34 AM   Replies: 10

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  2/13/2011, 5:34 AM
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Hello Experts,
At present my shop total connected load is 1100 Kw & max demand reached is 225 KVA, nature of connected load is heavy industrial load (heavy machine + fabrication shop) with average load factor of 13%. My shop is under expansion phase & immediated future connected load is as follows. Connected load will be 1500 Kw. Now my question is for this additional load of 1500 Kw, even with assuming my present load factor as 13%, what capacity capacitor load bank I should plan & connect to my system.
Can any one guide/help me?
Thanks in advance.
DEEP.   

Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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  2/15/2011, 5:40 AM
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Hello Experts,
Is my question correct? or it is posted in wrong product conference?
DEEP.

Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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  2/15/2011, 6:40 AM
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Hello Experts,
Is my question correct? or it is posted in wrong product conference?
DEEP.

Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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  2/15/2011, 7:06 AM
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Hi

Below shows the power vector diagram.
The power consists of active, reactive and apparent power


   Active power (VI cosØ)
   ------------->
    \  Ø         |
      \            |
        \          | 
          \        |   Reactive Power (VI sinØ)
            \      |
              \    |
                \  |
                  \|
  

Active power (P) = V*I*cosØ

Reactive power (S) = V*I*sinØ

Apparent power (Q) = V*I


Here the useful power is the active power and the reactive power is due to the lagging power factor due to the connected loads. This power factor varies with each load and you need a power factor monitoring equipment to check the power factor each time.

To find out the capacitive bank you should know the system power factor (system power factor can be measured by a power factor meter when all the system is connected)

Here, you have 1500 kW load.

Ie, P = 1500

Hence S = 1500 / cosØ

And Q = sqrt(S2 – P2)

To compensate the power to unity, you need to provide “Q” amount of capacitive power.




=== Edited by RBM @ 2/15/2011 7:07 AM [GMT ] ===


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  2/15/2011, 10:29 AM
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RBM wrote:
Hi

Below shows the power vector diagram.
The power consists of active, reactive and apparent power


   Active power (VI cosØ)
   ------------->
    \  Ø         |
      \            |
        \          | 
          \        |   Reactive Power (VI sinØ)
            \      |
              \    |
                \  |
                  \|
  

Active power (P) = V*I*cosØ

Reactive power (S) = V*I*sinØ

Apparent power (Q) = V*I


Here the useful power is the active power and the reactive power is due to the lagging power factor due to the connected loads. This power factor varies with each load and you need a power factor monitoring equipment to check the power factor each time.

To find out the capacitive bank you should know the system power factor (system power factor can be measured by a power factor meter when all the system is connected)

Here, you have 1500 kW load.

Ie, P = 1500

Hence S = 1500 / cosØ

And Q = sqrt(S2 – P2)

To compensate the power to unity, you need to provide “Q” amount of capacitive power.


Hi RBM,
Thanks for your reply. I know therotical what is meant by power factor & how to improve it. My question is for addition of 1500 Kw, connected load, with say 15% of LF, with heavy induction type of load, what size & capacity capacitors, or capacitors banks needs to be connected?
Thakns,
DEEP.

Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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  2/22/2011, 11:02 AM
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Hi deep,
I think chapter 7.3 in this manual provides the requested information.
Regards
Sentronix
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  2/22/2011, 11:56 AM
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Hi Sentronix,
Thank you very much for your reply. I studied the mentioned chapter & found as useful. The chapter states to calculate the addtion/corrective capacitor bank, provided we know the values of KWH & KVArH. But my question is how to calculate the capacitor bank value before having/knowing these information i.e. when we know the total connected load value in KW only.(Designe related, like suppose if I have to add 900 KW load induction type, with LF of 20%, what rating capacitor bank should I connect)
Hope I am able to elaborate my query.
Thanks.
DEEP.

Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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  2/28/2011, 11:25 AM
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Hi deep,
It is simply as RMB mentioned in his answer. For any consumer - existing or future installation - you know active power and power factor, so you are able to calculate reactive power.
On http://en.frako.de/services-downloads,tabId,2269.html there is available "Manual of Power Factor Correction" by company FRAKO. In addition to detailed calculations it provides approximate estimates (page 9).
Regards
Sentronix
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  2/28/2011, 11:59 AM
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RBM wrote:
Hi

Hi RBM,
Thanks for your reply. I know therotical what is meant by power factor & how to improve it. My question is for addition of 1500 Kw, connected load, with say 15% of LF, with heavy induction type of load, what size & capacity capacitors, or capacitors banks needs to be connected?
Thakns,
DEEP.

Hi DEEPSTR2010

The link below gives a brief idea about calculating the capacitance value.

here also u need to know the pf of the connected load.

dont know if this helps...

(if u want to calculate the capacitance value then above link helps you)

rgds,
RBM
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  3/1/2011, 10:46 AM
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Hi RBM,
Thanks for your reply. But this is not the one I am looking for.

Tell me and I will forget. Show me and I will remember. Involve me and I will understand. -Confucius
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