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What is Power Factor and Why is it Important?

Power factor is the ratio between the KW(Kilo-Watts) and the KVA(Kilo-Volt Amperes) drawn by an electrical load where the KW is the actual load power and the KVA is the apparent load power. 

It is a measure of how effectively the current is being converted into useful work output and more particularly is a good indicator of the effect of the load current on the efficiency of the supply system. 

Power Factor = True Power/Apparent Power

All current flow will cause losses in the supply and distribution system. A load with a power factor of 1.0 results in the most efficient loading of the supply and a load with a power factor of 0.5 will result in much higher losses in the supply system. 

Power Factor Formula:

1). The Cosine of angle between Current and Voltage is called Power Factor.

P = VI Cosθ                OR
Cosθ = P / V I             OR
Cosθ = kW / kVA        OR
Cosθ = True Power/ Apparent Power

P = Power in Watts
V = Voltages in Volts
I = Current in Amperes
W = Real Power in Watts
VA = Apparent Power in Volt-Amperes or Watts
Cosθ = Power factor

2). The ratio between resistance and Impedance is Called Power Factor.

Cosθ = R/Z

R = Resistance in Ohms (Ω)
Z = Impedance (Resistance in AC circuits i.e. XL, XC and R known as Inductive reactance, capacitive reactance and resistance respectively) in Ohms (Ω)
Cosθ = Power factor

3). The ratio between Actual Power and Apparent Power is called power factor.

Cosθ = kW / kVA

kW = Real Power in Watts
kVA = Apparent Power in Volt-Amperes or Watts
Cosθ = Power factor


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