Electrical Engineering ⇒ Topic : Most Economical Power Factor

Most Economical Power Factor

When a consumer improves the power factor, there will be reduction in kVA demand. So there will be annual saving over the maximum demand charges. Since the consumer has to bear the annual expenditure for p.f. correction equipment, the net annual saving will be equal to the annual saving in maximum demand charges, minus annual expenditure incurred on the account of p.f. correction equipment.

Most economical power factor is defined as the value of which the p.f should be improved so as to have maximum net annual saving.

In Figure (a), cos Φ₁ is original p.f. and cos Φ₂ is p.f. after adding p.f. correction equipment

                                   figure (a)

 ...............(1)

        ................ (2)

Subtracting Eq. (1) from Eq. (2), we get

Most economical power factor is given by

                                          ............... (3)

Here cos Φ₂ in Eq. (3) depends on the relative costs of supply and p.f. correction equipment but is independent of initial p.f. (cos Φ₁).