Answer the following questions on power factor a What is the

Answer the following questions on power factor:

(a) What is the purpose of power factor correction and why?

(b) How does the reactive power consumed in the load (excluding the power factor correction capacitor) differ before and after the power factor correction?

(c) How does the reactive power supplied by the source differ before and after the power factor correction?

(d) Explain the concept of reactive power. Does it have any implications on the utility? Why?

(e) For a lagging power factor, what type of element would you add to improve the power factor? Why?

Solution

(a)

Due to inductive loads there will be a apparent change or reduction in the total current drawn from the supply so in order to overcome this power factor correction is done and this power factor correction can be achieved as a result of connecting a capacitor to an inductive load.

(b)

Generally due to inductive loads the reactive power will increases and due to this reactive power there will a lot of reduction of the current which is drawn from the supply due to this reactive power the load on cables will increases and also the supply will not be able to supply for additional load. So after correction of this power factor the load on the cables will be reduced and also the supply will able to support additional load.

(c)

some of the loads require reactive power so to supply this reactive power VARS are connected in the source side so depending upon how much reactive power is required the VARS will supply that much of power.

(d)

Generally under normal operating conditions certain electrical loads draw not only active power (kW)from the supply but also the reactive power ( kVAr). This reactive power has no useful function, but is necessary for the equipment to operate correctly. Loads such as induction motors, welding equipment, arc furnaces comes under this category.

(e)

For a lagging power factor, the type of element which is added to improve the power factor is capacitor or synchronous condensor.