This document summarizes a literature review on power quality issues in industries. It was prepared by five students under the guidance of Prof. N.R. Bhasme. The document defines power quality and discusses various power quality problems such as disturbances, imbalance, distortion, fluctuations and flicker. It describes these problems in detail and lists their possible causes. It also discusses who is affected by power quality issues and how. The document covers monitoring of power quality parameters and the benefits of monitoring. It concludes by emphasizing that power quality issues can result in significant financial losses for businesses.

1. Power Quality Issues in
Industries
Under the guidance of
Prof. N.R. Bhasme
Ajay Sahu (BE09F03F027)
Ketan Bhavsar(BE09F03F034)
Dhammanand Bansode(BE09F03F048)
Umeshsing Maher(BE09F03F052)
Mithilesh Pohnerker(BE09F03F60)
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2. Literature Survey

3. Content
• WHAT IS POWER QUALITY
• PQ PROBLEMS
• DESCRIPTION OF PQ PROBLEMS
• WAVEFORMS:PQ DEFINITIONS
• SOURCES OF PQ PROBLEMS
• PQ PROLEMS & POSSIBLE CAUSES
• WHO GET AFFECTED
• HOW THEY AFFECT
• HOW TO MONITOR
• BENEFITS OF PQ MONITORING
• CONCLUSION
• REFERENCE
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4. What is Power Quality?
The term Power quality is used to describe the extent of
variation of the voltage, current and frequency on the power
system. The variation of voltage and current can either be in
terms of magnitude or waveform shape/distortion.
What Is Power Quality Monitoring?
The best way to detect and diagnose the problems in
electrical power system is called Power quality monitoring
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5. Why PQ is such a Big Problem?
– The sensitivity of today’s electronic equipment
makes it susceptible to power disturbances
– For some devices, a momentary disturbance can
cause
• scrambled data
• interrupted communications
• a frozen mouse
• system crashes and equipment failure
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6. Power Quality Problems
• 1.Disturbance
I. Voltage sag
II. Voltage interruption
III. Voltage swell
IV. Transient
V. Voltage notch
• 2.Imbalance
• 3.Distortion
• 4.Voltage fluctuation
• 5.Voltage flickering
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7. Description
• 1.Disturbances
A disturbance is defined as the temporary deviation from the steady state
waveform.
• Voltage Sag
Reduction in voltage magnitude for a short period of time.
• Voltage interruption
Voltage sag with 100% reduction in amplitude.
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8. • Voltage swell
Increase in RMS voltage or current at the power frequency between
1.1 to 1.9 per unit for a duration of 8milisec to 1min.
• Transient
Voltage disturbance shorter than sag/swell and are caused by sudden
changes in power system.
• Voltage notch
Periodic transient occurring within each cycle.
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9. • 2.Imbalance
A situation in which voltage, frequency and phase all are
different.
• 3. Distortion
It is generally expressed in terms of harmonics which are
sinusoidal voltages or currents having frequency that are integer
multiple of the frequency at which the supply system is designed
to operate.
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10. • 4. Voltage fluctuation
The rapid change in voltage magnitude in the allowable limit I.E., 95% to
105%.
• 5.Voltage flickering
The color occurring when the frequency of variation of light flux lies between
few hertz and fusion frequency.
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11. PQ Definitions Revisited
IEEE Categories
Std 1159-1995
Short Duration Typical
Variations Duration
Instantaneous Sag 0.5 – 30 cycles
Momentary Sag 30 cycles – 3
sec
Temporary Sag 3 sec – 1 min
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12. PQ Definitions Revisited
IEEE Categories
Std 1159-1995
Short Duration Typical
Variations Duration
Instantaneous Sag 0.5 – 30 cycles
Momentary Sag 30 cycles – 3
sec.
Temporary Sag 3 sec – 1 min.
Instantaneous Swell 0.5 – 30 cycles
Momentary Swell 30 cycles – 3
sec.
Temporary Swell 3 sec – 1 min.
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13. PQ Definitions Revisited
IEEE Categories
Std 1159-1995
Short Duration Typical
Variations Duration
Instantaneous Sag 0.5 – 30 cycles
Momentary Sag 30 cycles – 3
sec.
Temporary Sag 3 sec – 1 min.
Instantaneous Swell 0.5 – 30 cycles
Momentary Swell 30 cycles – 3
sec.
Temporary Swell 3 sec – 1 min.
Momentary Interruptions 0.5 – 30 cycles
Temporary Interruptions 30 cycles – 3
sec.
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14. PQ Definitions Revisited
IEEE Categories
Std 1159-1995
Long Duration Typical
Variations Duration
Sustained interruptions > 1 min
Under voltages > 1 min
Over voltages > 1 min
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15. PQ Definitions Revisited
IEEE Categories
Std 1159-1995
Long Duration Typical
Variations Duration
Sustained interruptions > 1 min
Under voltages > 1 min
Over voltages > 1 min
Voltage imbalance Steady state
Waveform Distortion
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16. PQ Definitions Revisited
IEEE Categories
Std 1159-1995
Long Duration Typical
Variations Duration
Sustained interruptions > 1 min
Under voltages > 1 min
Over voltages > 1 min
Voltage imbalance Steady state
Waveform Distortion
DC offset Steady state
Harmonics Steady state
Inter harmonics Steady state
For Electric Utilities Control of Voltage and Prevention of Outages is Power Quality
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17. Who is Affected?
• High Cost Facilities
o Semiconductor plants
o Pharmaceuticals
o Data centers
• Medium Cost Facilities
o Automotive manufacturing
o Glass plants
o Plastics & Chemicals
o Textiles

18. Sources of PQ Problems
Internal Sources
• Utility Sources
– Lightning • Individual Loads –Lighting, Elevators, Coolers, HVAC
– PF Correction • Uninterruptible Power Supplies
Equipment
• Variable Frequency Drives
– Faults
– Switching • Battery Chargers
• Large Motors During Startup
• Electronic Dimming Systems
• Lighting Ballasts (esp. Electronic)
• Arc Welders, and Other Arc Devices
• Medical Equipment, e.g. MRIs and X-Ray Machines
• Office Equipment and Computers
• Wiring
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19. PQ Problems and Possible Causes
Typical problems Disturbance Type Possible Causes
Overheated neutral Steady-state Shared neutrals
Intermittent lock-ups Improper or inadequate wiring
Frequency deviations High source impedance
SCR/Rectifiers and notching
Harmonics
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20. PQ Problems and Possible Causes
Typical problems Disturbance Type Possible Causes
Overheated neutral Steady-state Shared neutrals
Intermittent lock-ups Improper or inadequate wiring
Frequency deviations High source impedance
SCR/Rectifiers and notching
Harmonics
Interruption Utility faults
Garbled data Inrush currents
Random increase in harmonics levels Inadequate wiring
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21. PQ Problems and Possible Causes
Typical problems Disturbance Type Possible Causes
Overheated neutral Steady-state Shared neutrals
Intermittent lock-ups Improper or inadequate wiring
Frequency deviations High source impedance
SCR/Rectifiers and notching
Harmonics
Interruption Utility faults
Garbled data Inrush currents
Random increase in harmonics levels Inadequate wiring
Intermittent lock-ups Sags/Swell Source voltage variations
Lights flicker Inrush/surge currents
Garbled data Inadequate wiring
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22. PQ Problems and Possible Causes
Typical problems Disturbance Type Possible Causes
Overheated neutral Steady-state Shared neutrals
Intermittent lock-ups Improper or inadequate wiring
Frequency deviations High source impedance
SCR/Rectifiers and notching
Harmonics
Interruption Utility faults
Garbled data Inrush currents
Random increase in harmonics levels Inadequate wiring
Intermittent lock-ups Sags/Swell Source voltage variations
Lights flicker Inrush/surge currents
Garbled data Inadequate wiring
Component failure Impulses Lightning
Dielectric breakdown EMI/RFI Load switching
Lock-ups Capacitor switching
Garbled data Static discharge
Wavy CRTs Hand-held radios
Loose wiring/arcing
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23. PQ Problems and Possible Causes
Typical problems Disturbance Type Possible Causes
Overheated neutral Steady-state Shared neutrals
Intermittent lock-ups Improper or inadequate wiring
Frequency deviations High source impedance
SCR/Rectifiers and notching
Harmonics
Interruption Utility faults
Garbled data Inrush currents
Random increase in harmonics levels Inadequate wiring
Intermittent lock-ups Sags/Swell Source voltage variations
Lights flicker Inrush/surge currents
Garbled data Inadequate wiring
Component failure Impulses Lightning
Dielectric breakdown EMI/RFI Load switching
Lock-ups Capacitor switching
Garbled data Static discharge
Wavy CRTs Hand-held radios
Loose wiring/arcing
Overheated transformers and motors Harmonics Electronic loads
Voltage and current distortions SCR/rectifier
Garbled data
Lock-ups
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24. Major PQ Problems
Outages,
6%
Spikes, 7%
Swells,
Sags, 56%
31%
Swells Sags (Dips)
System fault conditions Associated with system faults
Switching on a large capacitor bank Switching of heavy loads
Switching off a large load Starting of large motors
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25. How Do They Affect You
• Motors stall
• Computers crash
• Production is affected
• Equipment damaged
• Product spoilage
• ‘The lights go out’
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26. How To Monitor PQ Parameters?
POWER QUALITY PROBLEM SOLUTION
VOLTAGE SAG UPS,DVR,CVT
VOLTAGE INTERRUPTION UPS
VOLTAGE SWELL UPS,POWER CONDITIONER
TRANSIENT SVC
VOLTAGE NOTCH SNUBBER CKT
IMBALANCE PROTECTION SCHEME
DISTORTION SERIES & SHUNT ACTIVE FILTER
VOLTAGE FLUCTUATION SVC
VOLTAGE FLICKERING VOLTAGE UNBALANCED RELAY
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27. Cost of Voltage Sags
Textile Industry
Plastics Industry
Glass Industry
Process Industry
Semiconductors
$1k $10k $100k $1M $10M
Losses per Voltage Sag Event
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28. Benefits Of Power Quality Monitoring
Direct Benefits / Technical Benefits
• – Energy Savings
• – Release of blocked capacity
• – Reduced temperature rise
• – Increased reliability / Life of equipment (e.g. Transformer, Motors,
capacitors...)
• – Reduced mal-function of equipment (e.g. Drives, Relays, Meters)
Indirect / Regulatory Benefits
• – Penalty savings / Incentives (e.g. Demand charges, Pf penalty)
• – Tax benefits
• – Compliance to standards & Regulations
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29. PQ is a Business Problem
• Power Quality issues cause business problems
such as cost productivity, idle people and
equipment
– Lost orders, good will, customers and profits
– Lost transactions and orders not being
processed
– Revenue and accounting problems
– Customer and/or management dissatisfaction
– Overtime required to make up for lost work time
According to Electric Light and Power Magazine, 30 to 40 Percent of All
Business Downtime Is Related to Power Quality Problems.
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30. PQ Problems are Expensive
– Berkeley Lab Study Estimates $80 Billion Annual
Cost of Power Interruptions … Research News,
Berkeley Lab, February 2, 2005
– $50 billon per year in the USA is lost as a results of
power quality breakdowns …. Bank of America
Report
– A manufacturing company lost more than $3
million one day last summer in Silicon Valley when
the “lights went out.” … New York Times January
2000
– “A voltage sag in a paper mill can waste a whole
day of production - $250,000 loss” … Business
Week, June 17,, 1996
– Half of all computer problems and one-third of all
data loss can be traced back to the power line …
Contingency Planning Research, LAN Times
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31. Conclusion
• Disturbances place all businesses at risk both in
terms of financial losses and energy efficiency so
they should be taken seriously.
• Power quality monitoring is very essential to get an
uninterruptable and efficient power supply.
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32. References
• Understanding Power Quality Problems – Voltage
Sags & Interruptions, Math H J Bollen, Ieee
Press.
• An Integrated Approach To Power Quality
Improvement, R Venkatesh & S R Kannan, - Et
Power Tech 2001.
• Solutions To The Power Quality Problem, Prof.
Ray Arnold, iee Power Engineering Journal, April
2001
• Power Quality Issues A Distribution Company
Perspective,iee Power Engineering Journal, April
2001
• Monitoring Power For The Future, Afroz K. Khan,
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33. Thank You!
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