Power factor

1. Power Factor
By Md. Rasedul Islam
MSc. in Nuclear Power Engineering and Thermal Physics
NATIONAL RESEARCH NUCLEAR UNIVERSITY (NRNU) MEPhI,
Russia
OBNINSK INSTITUTE FOR NUCLEAR POWER ENGINEERING
(OINPE)
Md. Rasedul Islam 1

2. Content
• What is power factor?
• AC Powers
• Types of Loads
• Understanding Power Triangle
• Unity Power Factor (FP = 1)
• Lagging Power Factor (θ > 0º)
• Leading power factor (θ < 0º)
• Why do we improve power factor?
• Power factor improvement methods
• Power factor correction design
• Basic Scheme of the NPP Circuit
• Safety System of VVER-1200
Md. Rasedul Islam 2

3. POWER FACTOR
The cosine angle between the voltage and current in an a.c
circuit is known as power factor.
Power factor involves the relationship between two types
of power, working power and reactive power.
Poor P.F 0.60 P.F >0.90
Md. Rasedul Islam 3

4. A.C POWERS
Active Power:
Measured in watts (normally shown as kW). Provides the “working” part
of the power system. Producing heat, light, motion etc.
Active Power is the actual power which is really transferred to the load.
Reactive Power:
Measured in volt-ampere-reactive (normally shown as kVAR). It only
maintains the electromagnetic field and provides no “working” part of
the power system.
**Reactive power is temporarily stored in the form of electric or
magnetic fields that flows back and forth in the line, it acts as an
additional load.
Apparent Power:
Measured in Volt-Ampere (normally shown as kVA). Provided both
working and nonworking parts of the power system.
Md. Rasedul Islam 5

5. A.C POWERS
Positive value of power waveform represents the real or working
power which is delivered from the source to the load.
Negative value of power waveform represents the reactive power
which is returned from the load to the source.
From waveforms, 0 to t1, V and I are both positive; therefore,
power is positive. At t=t1, V is 0V and thus P is 0W. From t1 to t2,
I is positive and V is negative; therefore, P is negative. From t2
to t3, both V and I are negative; therefore power is positive, and
so on.
Md. Rasedul Islam 6

6. Types of Loads
Md. Rasedul Islam 7
Resistive load – Incandescent Lamp,Resistance heat
Resistor, R = R
Inductive load – Synchronous Motors(Low DC field
current), Induction Motors, Contactor Coils, Relays
Inductor, Zl = jωL,ω=2πf
Capacitive load – Capacitors, Synchronous Motor(High DC
field current),
Capacitor, Zc = 1/jωC,ω=2πf

7. A.C POWERS - Power Comparison
Md. Rasedul Islam 8

8. A.C POWERS
Md. Rasedul Islam 9
Beer is active power (kW)—the useful
power, or the liquid beer, is the energy
that is doing work. This is the part you
want.
Foam is reactive power (kVAR)—the
foam is wasted power or lost power. It’s
the energy being produced that isn't
doing any work, such as the production
of heat or vibration.
The mug is apparent power (kVA)—the
mug is the demand power, or the power
being delivered by the utility.

9. POWER FACTOR -Power Triangle-
Apparent power in a.c circuit has two components, active or
working power and reactive power.
From trigonometric relation,
Thus the power factor of a circuit may also be defined as
the ratio of active power to the apparent power.
For leading currents, the power triangle becomes reversed.
Md. Rasedul Islam 11

10. POWER FACTOR -Power Triangle-
Now the power factor can be defined in one of the following 3
ways:
1. Power factor = cosѲ = cosine angle between V and I.
2. Power factor = cosѲ = Resistance/Impedance.
3. Power factor = cosѲ = Active power/Apparent power.
Let us assume a circuit having current of 10 A at a
voltage of 200 V and its power factor is 0.8 lagging.
S = VI = 200(10) = 2000VA =
2KVA
P = VI cosѲ = 200(10)(0.8) =
1.6KW
Q = VI sinѲ = 200(10)(0.6) = 1.2kVAR
The circuit receives an apparent power of 2KVA and is able to
Md. Rasedul Islam 12

11. Unity Power Factor, Pf = 1
If circuit is resistive, both current and voltage are in phase with
each other and power factor is referred as unity.
A unity power factor implies that all of a load’s apparent power is real
power (S = P). Now, if FP = 1, then θ = 0º
Md. Rasedul Islam 13
Why are current and voltage in phase with each other in resistive load?
Instantaneous voltage and current are in-phase because the current and
the voltage reach their maximum values at the same time.

12. Lagging Power Factor (θ > 0º)
If the circuit is inductive, the current lags behind the voltage by
an angle Ѳ and power factor is referred to as lagging.
The load current lags the load voltage
Md. Rasedul Islam 14
Why does current lag behind voltage in inductive load?
When a voltage is applied to a inductor, it resists the change in current. The current
build up more slowly then the voltage, lagging it in time and phase.

13. Leading power factor (θ < 0º)
If the circuitiscapacitive, the current leadsthe voltagebyanangleѲand
powerfactor isreferred to asleading.
Theloadcurrentleadstheloadvoltage
Md. Rasedul Islam 16
Why does current lead behind voltage in capacitive load?
Since the voltage on a capacitor is directly proportional to the charge on it, the
current must lead the voltage in time and phase to conduct charge to the
capacitor plates and raise the voltage

14. POWER FACTOR
Different typesof electrical loadhave different PowerFactorsaccording
to itsnature.
Name of Equipment Power Factor Percent
Lightly loaded induction motor
Full Loaded induction motor
Neon-lighting equipment
Incandescent lamps
0.20 Lagging
0.80 Lagging
0.30 - 0.70 Lagging
1.0 Unity
All types of resistance heating
devices (e.g. toaster, heater)
1.0 Unity
Md. Rasedul Islam 18

15. Why do we improve the power factor?
The reason for improving the power factors are stated below;
•Large Line Losses (Copper Losses): Line losses (I2R) depend on current.
The low power factor draws a large amount of current as compared to the
high power factor.
•Large kVA rating and Size of Electrical Equipment; PF is inversely
proportional to KVA. Low PF equipment with a high KVA rating is larger in
size.
•Large Conductor Size and Cost; we need large conductors to transmit the
heavy current required due to low power factor.
•Poor Voltage Regulation and Large Voltage Drop; The large current due
to low PF causes a high voltage drop that needs to be regulated more often
than usual.
•Low Efficiency; The losses due to the high current flow & voltage drop
deteriorate the efficiency of the system. The efficiency is maximum at PF=1.
Md. Rasedul Islam 21

16. Power factor improvement methods
Md. Rasedul Islam 22
1) Static Capacitor method
2) Synchronous condenser method
3) Phase advancer’s Method
The capacitor helps in providing a leading current that
eliminates the lagging component of current & improves
the power factor
It is an over-excited synchronous motor with no load
that also provides a leading power factor. A synchronous
condenser is a DC-excited synchronous machine (large
rotating generators) whose shaft is not attached to any
driving equipment.
For inductive loads, a synchronous condenser is connected towards the load side
and is overexcited. Synchronous condensers make it behave like a capacitor. It draws
the lagging current from the supply or supplies the reactive power.
Phase advancer is a simple AC exciter which is connected on the main
shaft of the motor and operates with the motor’s rotor circuit for
power factor improvement. It improves the power factor by providing
the exciting ampere turns to produce the required flux at the given
slip frequency.

17. Power factor correction design
Md. Rasedul Islam 23

18. Conclusion
Md. Rasedul Islam 24
High Power Factor
- Eliminates power factor penalty
- Reduction Of I2R Losses
- Reduces Generators, Transformers size
- Low Voltage drops
- Save energy

19. Research & Publications
Md. Rasedul Islam 27
1. Master’s Research: Pipeline Coolant Leak Detection System for 3rd Generation
Nuclear Power Plant.
2. Undergraduate Thesis: In-Body Antenna for Wireless Capsule Endoscopy and
Biotelemetry System.
3. Paper Title: “In-body Antenna for Wireless Capsule Endoscopy at MICS Band”-
presented in Computing Conference 2018 10-12 July 2018 | London, UK. Published
in Intelligent Computing. SAI 2018. Advances in Intelligent Systems and Computing,
vol 857. Springer, Cham. DOI: https://doi.org/10.1007/978-3-030-01177-2_59
4. Paper Title: “Body Implantable Patch Antenna for Biotelemetry System”-
Published in 2018 International Electrical Engineering Congress (iEECON2018),
Thailand. DOI: 10.1109/IEECON.2018.8712300
5. Paper Title: “Heart Disease Detection by Using Machine Learning Algorithms and
a Real-Time Cardiovascular Health Monitoring System”. World Journal of
Engineering and Technology, Vol.06 No.04(2018), Article ID:88650, 20 pages (854-
873). DOI: https://doi.org/10.4236/wjet.2018.64057

20. Thank You