Table of contents | |
Power Factor | |
Power Triangle | |
Analysis | |
Power Factor Improvement Equipment | |
Phase Advancers |
The cosine of angle between voltage and current in an a.c. circuit is known as Power Factor.
The power triangle is a graphical representation used in electrical engineering to illustrate the relationship between different types of power in an AC (alternating current) circuit. The three types of power represented in the power triangle are:
Real Power (P): This is the actual power consumed by the circuit to perform useful work, measured in watts (W). It is represented on the horizontal axis of the power triangle.
Reactive Power (Q): This is the power that oscillates between the source and the load, contributing to the establishment of electric and magnetic fields. It does not perform any useful work and is measured in volt-amperes reactive (VAR). It is represented on the vertical axis of the power triangle.
Apparent Power (S): This is the total power supplied to the circuit, combining both real and reactive power. It is measured in volt-amperes (VA) and is represented as the hypotenuse of the power triangle.
The power triangle is a right triangle where:
The relationship between these powers can be expressed using the Pythagorean theorem:
kVAr = kW tanf
Example
Let, Voltage = 200 V, current = 10A,
Power factor = cosf = 0.8 lagging
Then, Apparent power = VI = 200 × 10 = 2000 VA
and, Active power = VI cosf = 200 × 10 = 0.8 = 1600 W
Reactive power = VI sinf = 200 × 10 × 0.6 = 1200 VAR.
Causes of Low Power Factor Low power factor is undesirable from economic point of view. Normally, the power factor of the whole load on the supply system is lower than 0.8.
Following Reason :
Disadvantages of Low Power Factor
Large kVA Rating of Equipment
Greater Conductor Size
Large Copper Losses
Poor Voltage Regulation
Reduced handling capacity of system
Power Factor Improvement
The capacitor draws a leading current.
I cos f1 = I' cos f2
I' sin f2 = I sinf – Ic (capacitor current)
but I cos f1 = I' cos f2
VI cos f1 = VI' cos f2
(No change in active power (KW) due to p.f. correction (improvement)
I' sinf2 = I sinf1 – Ic VI' sinf2 = VI sinf1 = VIc
Net KVAR after p.f. correction = lagging KVAR before p.f. correction leading KVAR of equipment
Static capacitor The power factor can be improved by connecting capacitors in parallel with the equipment operating at lagging p.f. The capacitor (generally known as static capacitor) draws a leading current.
Synchronous condenser An over excited synchronous motor running on no-load is known as synchronous condenser. When such an electrical machine is connected in parallel with the supply it takes a leading current which partly neutralises the lagging reactive component of the load.
Thus the power factor is improved.
Advantages:
Disadvantages:
Note:
Disadvantage:
Importance of Power Factor Improvement For Consumers
Annual Profit
For generating station
Note:
Most economical power factor The value to which the p.f. should be improved so as to have maximum net annual saving is known as the most economical power factor.
23 videos|89 docs|42 tests
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1. What is power factor and why is it important in electrical engineering? |
2. How does power factor improvement equipment, such as phase advancers, help in optimizing power factor? |
3. What are the benefits of using power factor improvement equipment in electrical systems? |
4. How can electrical engineers determine if power factor improvement equipment is needed in a specific electrical system? |
5. Are there any potential drawbacks or limitations to using power factor improvement equipment in electrical systems? |
23 videos|89 docs|42 tests
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