1. Presentation on
“Power Quality”
Mr. P B Tupe

2. Presentation Sections
What is Power Quality?
Why Monitor Power Quality?
Power Quality components
European Standard EN50160
IEC Standard
What should we demand from a PQM?

3. Steady-state disturbance
What is Power Quality?
Steady-state disturbance
Transient
disturbance

4. What is Power Quality? IEEE
..the concept of powering and grounding sensitive electronic equipment in a manner suitable for the equipment
LPQI (Leonardo Power Quality Initiative)
..a supply that is always available, always within voltage and frequency tolerance, with a pure, noise free, sinusoidal wave shape
Sankaran (modified)
..a set of boundaries that allow electrical appliances and systems to function as intended without significant loss of lifetime or performance
In our first Annual Group Management Meet in 1999 we had showed a set of two slides, the first showing what we called our “Existing Objectives” and the second what we had identified as our future Challenges.
Our existing objectives, we had then said, are to improve our performance, to create value for our shareholders, to become a world-class player, to be No 1 or No 2 in the market and to be market-oriented. If you think about it, these are a compact, inter-related set of objectives which had emerged out of our past performance.

5. A Brief History of Power Quality…
1879
1891
1917
1948
2006
First report on flicker
Thomas Alva Edison invents the light bulb
Jonas Wenström invents the three- phase system
Shockley, Bardeen and Brittain invents the first transistor
Increased use of power electronics
Mostly linear loads
Increase in non-linear loads
The most severe power quality problems started to appear at the beginning of the 1950’s. This was due to the development of transistors which lead to non-linear loads in the power network. Computers, printers, and all other power electronic products represent non-linear loads.

6. Why Monitor Power Quality?
The Cost of (poor) Power Quality:
Production losses
Extended outage time
Shortened equipment lifetime e.g. Transformer
Unexpected early failure
Overloading of equipment
Potential catastrophic failure
Chain reaction
In our first Annual Group Management Meet in 1999 we had showed a set of two slides, the first showing what we called our “Existing Objectives” and the second what we had identified as our future Challenges.
Our existing objectives, we had then said, are to improve our performance, to create value for our shareholders, to become a world-class player, to be No 1 or No 2 in the market and to be market-oriented. If you think about it, these are a compact, inter-related set of objectives which had emerged out of our past performance.

7. Why Monitor Power Quality?
According to a study performed by European Copper Institute in 2001, covering 1,400 sites in 8 countries, any given site in Europe has a 5-20 % probability that it will suffer from one or more of the problems listed. Typically, half of sites in energy-intensive industries or mission-critical office buildings will suffer from two or more problems
In our first Annual Group Management Meet in 1999 we had showed a set of two slides, the first showing what we called our “Existing Objectives” and the second what we had identified as our future Challenges.
Our existing objectives, we had then said, are to improve our performance, to create value for our shareholders, to become a world-class player, to be No 1 or No 2 in the market and to be market-oriented. If you think about it, these are a compact, inter-related set of objectives which had emerged out of our past performance.

8. Why Monitor Power Quality?
Estimation of annual cost of poor PQ in Europe
10 billion EUR
Power quality problems have increased since 2001 due to more sensitive equipment and more non-linear loads.
Typical losses in some industries due to poor PQ (2001)
Semiconductor production EUR
Financial trading (per hr!) EUR
Computer centre EUR
Telecommunications (per min!) EUR
Steel works EUR
Glass industry EUR
Ref : Copper Development Association’s booklet 2001

9. Power Factor Description / Causes:
Phase angle between voltage and current. Caused by capacitive or inductive loads such as:
Motors
Long power lines.
Consequences:
Costs:
Inefficient use of grid
Overheating
Losses
Network must be designed for higher currents

10. Supply voltage variations
Description / Causes:
Slow variations in the RMS.
Caused by:
Changing loads
Tap changes on transformers
Consequences:
Costs:
Reduced life time of equipment
Production losses
Damage to equipment
Production losses
Reduced life time of equipment

11. Harmonics Description / Causes:
Non-linear loads cause distorsion that causes other (higher) frequencies in the network.
Caused by:
Switched power supplies (computers), Power electronics, Motor drives
Consequences:
Costs:
Increased losses. Overheating of neutral conductor and transformers
Resonance phenomena resulting in high currents and voltages. Broken capacitor banks.
Malfunction in control equipment
Production losses
Reduced life span of the equipment
Increased investments in filters and compensating equipment

12. Flicker Description / Causes:
Cyclic variations in the voltage RMS. Variations in the range 0-30 Hz.
Caused by:
Welding equipment
Rolling mills
Arc-furnaces
Consequences:
Costs:
Blinking lights that irritate and tire the eye and cause headaches
Indirect costs like reduced productivity
Often expensive solutions

13. Voltage unbalance Description / Causes:
Amplitude and/or phase varies between the three phases.
Caused by:
Uneven distribution of single-phase loads
Trains
Consequences:
Costs:
Loss of efficiency in 3 Ph motors
Corrosion and increased current in neutral conductors.
Stray currents in grounding system
Reduced life span of the equipment
Motor power cannot be fully utilised

14. Transients Description / Causes:
Rapid and short (sub-cycle) changes in the voltage or current waveforms.
Caused by:
Lightning
Faults and switching in the grid
Start of engines
Consequences:
Costs:
Tripping of protective equipment
Faults/damages in electronics such as computers or control systems for machines
Production loss
Failure or damage to equipment
Loss of information (computers)

15. Sags (dips) / Swells Description / Causes:
Short variations in voltage RMS.
Caused by:
Lightning
Faults and switching in the grid
Start of engines, rolling mills, welding sets
Consequences:
Flicker
Disturbances in electronic equipment such as computers or control systems for machinery
Swells can destroy equipment (overvoltages)
Costs:
Production losses
Loss of information in computers

16. Rapid Voltage Changes Description / Causes:
Fast but small (<10%) variations in the voltage RMS.
Caused by:
Connection/disconnection of loads
Tap changes on transformers
Consequences:
Flicker
Costs:
Indirect costs such as reduced productivity

17. Power (Poor) Quality
In our first Annual Group Management Meet in 1999 we had showed a set of two slides, the first showing what we called our “Existing Objectives” and the second what we had identified as our future Challenges.
Our existing objectives, we had then said, are to improve our performance, to create value for our shareholders, to become a world-class player, to be No 1 or No 2 in the market and to be market-oriented. If you think about it, these are a compact, inter-related set of objectives which had emerged out of our past performance.

18. Two categories of PQ standards
Voltage characteristics standards
EN (EU standard)
IEC (LV), -12 (MV)
Norma Peruana (Peru)
Victorian Distribution Code (Australia)
Philippine Grid Code
Venezuelan Grid Code
Chinese standards
Measurement methods standards
IEC (harmonics)
IEC (flicker)
IEC (methods)

19. Voltage characteristics for electricity supplied by
European Standard EN50160
Voltage characteristics
for electricity
supplied by
public distribution systems
Main characteristics of voltage at customer’s supply terminals
Public low-voltage and medium-voltage networks
Describes what is expected under normal operating conditions

20. EN50160 - Voltage variations
Voltage magnitude: 95% of the 10-minute averages during one week shall be within 10% of the declared voltage of 230 V. All values shall be between -15% and +10%.
Frequency: 99.5% of the 10-second averages during one year shall be between 49.5 and 50.5 Hz. The frequency shall
be between 47 and 52% for 100% of the time.
Voltage unbalance: 95% of the 10-minute averages during one week shall be less than 0.02.
Voltage fluctuations: 95% of the 2-hour long-term flicker severity values during one week shall not exceed 1.0.

21. EN50160 - Voltage variations (2)
Voltage harmonics: 95% of the 10-minute averages during one week shall not exceed the values given in the table below
Note: As for all other characteristics these values hold for 99.9% of the locations during 95% of time

22. European Standard EN50160 – in short

24. Describes measurement methods which will give
IEC Scope
Describes measurement methods
which will give
reliable, repeatable and comparable results
- regardless of the instrument being used
Focused on parameters causing conducted phenomena
Describes measurement methods – not thresholds or limits

25. IEC PQ Parameters
Detailed specification of measurement methods and accuracy for:
Power frequency
Voltage RMS
Flicker
Harmonics and interharmonics
Unbalance
Dips, swells, interruptions and transients
Mains Signalling

26. IEC 61000-4-30 Class A – Normative High accuracy Standards compliant
Contractual verification
Comparable results
Class B – Indicative
Lower accuracy
May not meet all standards
Demand analysis
Results vary with instrument

27. IEC 61000-4-30 Flagging Concept
When a single event such as a
voltage DIP etc. occurs, the
actual measurement interval
shall be flagged and other
parameters should be
discarded during that interval
to avoid counting the event more
than once.
New method !

28. Voltage RMS value The RMS value is calculated from
every 10-cycle value
without time gaps.
Other measurement
intervals can be
calculated based
on 10-cycle values.
Accuracy 0.1%
of nominal voltage. T

29. ½ Cycle RMS values = 10ms (for DIPS detection)
Performance specification, not a design specification !
½ Cycle RMS values = 10ms (for DIPS detection)
Measurement Aggregation time interval:
10 Cycles = 200ms
150 Cycles = 3s
10min Values are calc from 10 cycle values
2Hr Value = aggregated from 12 x 10min values
In our first Annual Group Management Meet in 1999 we had showed a set of two slides, the first showing what we called our “Existing Objectives” and the second what we had identified as our future Challenges.
Our existing objectives, we had then said, are to improve our performance, to create value for our shareholders, to become a world-class player, to be No 1 or No 2 in the market and to be market-oriented. If you think about it, these are a compact, inter-related set of objectives which had emerged out of our past performance.
Class A devices - tested thoroughly as per guidelines
Class B devices – Liberty to manf to specify the methods and accuracies
Results of 2 Class A devices an be compared.

30. Sliding reference
Nominal levels might vary over time, especially on medium and high voltage.
Threshold values must therefore always follow the actual reference level. This is called sliding reference since reference level is always average voltage last minute.
Sliding Reference

31. IEC Summary
IEC provides standardised measurement methods
IEC guarantees comparable results between normative instruments
IEC guarantees users to have full knowledge about the instrument performance
IEC helps manufacturers of PQ instruments to implement standardised methods and algorithms
IEC is an essential document when developing new PQ standards

32. What should we demand from a power quality monitoring system?
Accurate and reliable measurement
Measure both voltage and current for disturbance tracking
IEC Class A instrument
Combination of permanent and portable instruments for full control of the whole network
Portable unit suitable for field use: IP65
Designed for power quality monitoring:
Remote communication solutions for both permanent and portable instruments
Automated features: user defined limits, alarms etc
Give statistical information: data stored for years, not just months

33. Reference IEC/ EN Standards
Web sites / Product catlogues – Unipower ,Yokogawa, Fluke, GE, Areva, a-eberle, Megger, ABB, Siemens etc.
www. Lpqi.com (Leonardo Power Quality Initiative)
Copper Development Association’s Reports