Explain why the power factor is not in unity and what could be the advantage of a unity power factor
Power factor is the measure of effectiveness on how you are using electricity. It’s given as the ratio of the active power consumed by the device to the total power supplied.
Most of the loads used in industries are inductive in nature. As we know in inductive loads current lags voltage. So it’s difficult to obtain a unity power factor due to the nature of loads used unless Pure resistive loads.
So power factor can be improved to near unity (0.8 or 0.9)… To improve power factor different methods are used such as
(i) Capacitor banks
Capacitors are connected in parallel with the loads having power factor to be improved… Capacitors generate capacitive reactive power therefore the lagging reactive power demand of the equipment is locally supplied by the static capacitor. Thus the p.f is improved
(ii)Synchronous Condenser
A synchronous condenser is an over-excited synchronous motor. When the synchronous motor is over-excited, it takes current leading by an angle of 90° from the supply voltage. This simply means that it behaves like a capacitor.
Power factor correction is achieved by connecting synchronous condenser in parallel with the inductive load whose p.f is to be improved.
In an AC power system, the power factor is a very important parameter that defines how efficiently electrical power is being utilized by the load. It is a rational number between -1 and 1 but has no unit. The p.f of a system depends on the type of load present, whether resistive, inductive, or capacitive. The inductive and capacitive load has a negative impact on the p.f. of the system. Poor p.f results in an increase in current drained by the load.
Power factor defines the phase difference between voltage current and it also indicates how much power is doing useful works and how much power is wasting. … As in the dc circuit, there is no phase difference between voltage and current power factor always unity or we can say dc has not power factor.The less is the power factor, the more is the reactive power generated. Reactive power is not very useful, hence considered as useless power. But due to the generation of this reactive power, the apparent power increases. Hence more cost and is not economical