Power factor is a ratio between actual power and apparent power in a circuit. A low power factor is caused by inductive loads like motors and transformers which draw lagging current. Improving power factor through devices like capacitors reduces line losses, improves voltage regulation, lowers electricity bills, and allows for more load to be served. Properly locating power factor correction equipment such as installing capacitor banks at substations instead of individual loads provides the benefits of power factor improvement in a cost effective manner.

1. CONTENTS…
 WHAT IS POWER FACTOR
 NEED OF IMPROVEMENT OF POWER FACTOR
 RELATION BETWEEN PF IMPROVEMENT & ENERGY SAVING
 HOW TO IMPROVE POWER FACTOR
 IMPACT OF PF ON THE SYSTEM
 LOCATION OF SHUNT CAPACITOR FOR PF IMPROVEMENT
 DIFFRENCE IN WORKING OF SHUNT CAPACITOR AND SYNCHRONOUS CONDENSER

2. Power Factor may be defined by three definitions and formals as follow.
1). The Cosine of angle between Current and Voltage is called Power Factor.
Cosθ = P / V I
2). The ratio between resistance and Impedance is Called Power Factor.
Cosθ = R/Z
3). The ratio between Actual Power and Apparent Power is called power
factor.
Cosθ = kW / kVA

3. Low lagging power factor conditions can be caused by various combinations of
the following inductive devices:
 Induction motors
 Inductive loads of fluorescent ballasts
 Rectifiers providing a DC power supply
 Arc welders
 Solenoids
 Induction heaters
 Lifting magnets
 Transformers.

4. ARC WELDER
TRANSFORMER
INDUCTION MOTOR
SOLENOIDS
MAGNET LIFTERS

6.  Why there is need to improve power factor?
 Why the power factor is important ?
 Exactly what is power factor correction?
 How the power factor will helps in the energy conservation?

7. Static capacitor
The power factor can be improved by connecting a capacitor in parallel with the
inductive load. As we know that capacitor draws a leading current which can
neutralize the lagging power factor produced by the inductive loads. For three
phase loads, the capacitors can be connected in star or delta.

8. Synchronous condenser
Synchronous motors take the leading current when they are over excited and therefore they behave
like capacitors. So an overexcited synchronous motors running at no load is called synchronous
condenser. When such machines are connected in parallel with the supply, it takes the leading current
which partially neutralizes or tend to minimize the low power factor. Hence the power factor is
improved.

10. Phase advancers
Phase advancer is also a power factor improvement device. As we know that the low power
factor is due to induction motor’s stator, because it draws very high current which lags behind
the supply voltage by 900. Phase advancer in real is an external ac excitation for the motor
which relieves the stator winding of exciting current and the power factor can be improved.

11. 1.) Large Line Losses (Copper Losses)
2.) Greater Conductor Size and Cost
3.) Poor Voltage Regulation and Large Voltage Drop
4.) Low Efficiency
5.) Penalty from Electric Power Supply Company on
Low Power factor

12. A Capacitor Bank has to go through different abnormal system conditions, during
its life span. To with stand these abnormalities at optimum manufacturing cost, the
capacitor banks are rated with following allowable parameters. A capacitor bank
should continue its service with in the following limits. 110 % of normal system
peak voltage.
120 % of normal system rms voltage.
135 % of rated KVAR.
180 % of normal rated rms current.
Specification of capacitor bank

13. Theoretically it is always desired to commission a capacitor bank nearer to reactive load.
This makes transmission of reactive KVARS is removed from a greater part of the network.
Moreover if capacitor and load are connected simultaneously, during disconnection of
load, Capacitor is also disconnected from rest of the circuit. Hence, there is no question of
over compensation. But connecting capacitor with each individual load is not practical in
the economical point of view. As the size of loads extremely differs for different
consumers. So various size of capacitors are not always readily available. Hence proper
compensation can not be possible at each loading point. Again each load is not connected
with system for 24 × 7 hours. So the capacitor connected to the load also can not be fully
utilized.
Hence, capacitor, is not installed at small load but for medium and large loads, capacitor
bank can be installed at consumer own premises. On viewing of these difficulties, instead
of connecting Capacitor to each load, large capacitor bank is installed at main distribution
sub-station or secondary grid sub-station.

15. ENERGY CONSERVATION AND POWER FACTOR
 Improve power factor by installing capacitors to reduced KVA demand charges and also
reduce line losses.
 Improvement of power factor from 0.85 – 0.96 will give reduction of 11.5 % peak KVA.
 And 21.6 % reduction in peak losses
 This corresponds to 14.5 % reduction in average losses for a load factor of 0.8

16. 1. REDUCED DEMAND CHARGES
2. INCREASED LOAD CARRYING CAPABILITIES IN EXISTING CIRCUITS
3. IMPROVED VOLTAGE
4. REDUCED POWER SYSTEM LOSSES
5. REDUCED CARBON FOOTPRINT