Power Factor : Understanding the Concept

TPWODLTP Western Odisha Distribution Limited

Objective of This Presentation

• Understanding the Concept of Power Factor, KVA and KVAR

• Benefits of PF Improvement (For Consumers as well as for utility)

• Usage of CAPACITORS

• Installation of Capacitor Banks - Over compensation and Under compensation

• Evaluation of Solutions with Cost Benefit Analysis

Power-Revisited: Concept of KW,KVA,PF and KVAR

• Power is the quantity required by any equipment to do any work. It isdefined as Kilo Watt (KW). This is also called the Real or Active or Usefulpower.

• Because of inherent property of some electrical equipments the powerdrawn by them is more than actually required. This value is called asApparent or Total power and is mentioned in Kilo Volt Amperes(KVA).

• KVA is the total of Useful power (KW) and Useless or Reactive power. ThisReactive power is mentioned in Kilo Volt Amperes Reactive(KVAr).

• Electrical equipment draws Useless power (KVAR) due to their inherentproperty and is indicated by a factor called power factor(PF). In electricalterm, it is mentioned as Cosø and may vary from -1 to 1.

Power-Revisited: Concept of KW,KVA,PF and KVAR (Contd..)

• Lower Power factor would mean higher useless power (KVAR) andvise versa.

• Equipments driven by electric Motors viz., Fans, Coolers, Pumps, anyother m/cs; Tube Lights, M.V & S.V lamps, Welding Machines,Rectifiers, Induction Furnace etc. have PF of 0.5 to 0.8. These loadsare called Inductive loads, have low P.F and draws higher uselesspower.

• Loads like Heaters, Resistance Furnaces have a higher power factor of0.95 to 0.99 and hence use less useless power.

• The ideal condition – Unity P.F. Then KW would be equal to KVA andUseless power would be zero.

Effects of Better Power Factor

a) It reduces the useless power.

b) All the power drawn becomes nearly equal to useful power i.e., itreduces the KVA.

c) It reduces the current and hence reduces line losses in cables,transformers etc.

d) Improves the voltage regulation because of reduced currents.

Benefits of Better PF

For Consumers:

• No PF Penalty / Reduced KVAh billing in New Tariff.

• Reduced Stress on Equipments hence less maintenance, longer life.

For Utility :

• Reduced Losses in Power transmission system viz., O.H Line, Cables, Transformers.

• Reduced loading on transformers, Less transformers failure.

• Better Voltage regulation - Better voltages at the user end.

• More Reliable supply and hence more satisfied consumers

For Society:

• A unit of Energy saved is unit generated - Valuable contribution to our nation when thedemand is more than the generation capacity.

How to Improve Power Factor

• Typical Inductive loads have PF less than ONE, thuslagging PF. They draw KVAR from the powersystem.

• Capacitors are called capacitive loads with LeadingPF. They pumps KVAR into the power system.

• The Power Factor Can be corrected by ProvidingCapacitors.

Explanation By Drawings

Methods of Capacitor Compensation

Fixed Compensation

• In this type of compensation a designed value ofcapacitors are connected to the load. These Capacitorsmay be permanently connected or manually switched on/ off using switches.

Automatic Variable Capacitors/APFC Panels

• These are Capacitor panels with contactors , fuses andintelligent relays which would be switching on thenecessary capacitors depending on the loading.

Comparison of Compensation Systems

Where all Capacitors Can be Put

Selection of Capacitors

a) The fixed type capacitors should be connected through a switch as they areput off during off peak or no load hours.

b) KVAH would be high if there is low leading or low lagging PF, so it isessential to ensure that excess Capacitors are not switched on to avoidOver compensation.

c) In case smaller requirement of 5-30 KVAR, switching on / off of capacitorsmay be done manually. For above 35 KVAR, its advisable to go forautomatic capacitor switching panels.

d) It is advisable to consult the capacitor manufacturers to design theoptimum system for the maximum savings and best payback .

Thank You!

Private and Confidential

Disclaimer: The contents of this presentation are private & confidential. Please do not duplicate, circulate or distribute without prior permission.

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