Consider a system having following loads , we want to improve the system power factor to 0.95

Equipment | Output KW | Efficiency | Load KW | Power factor | KVA |

Motor A | 30 | 0.9 | 33.3 | 0.8 | 41.7 |

Motor B | 90 | 0.92 | 97.8 | 0.85 | 115 |

Lighting | 20 | 0.85 | 23.5 | 0.95 | 25 |

Heaters | 10 | 10 | 1 | 10 | |

Total | 150 | 164.6 | 191.7 |

Total load in KW = 164.6

And total load in KVA = 191.7

Therefore , the average power factor of the system will be = 164.6/191.7 =0.86

As we want to improve this system power factor from 0.86 to 0.95.

Existing power factor = 0.86 = *Cos?*1 ; therefore tan *?*1 =0.593

Required power factor = 0.95 = *Cos?*2; therefore tan *?*2=0.328

So, amount of capacitors to be installed to improve power factor will be

= Total Load (tan *?*1 – tan *?*2)

= 164.6(0.593-0.328)

= 44 KVAr

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