# Ch2 Standards

date post

06-Feb-2016Category

## Documents

view

15download

0

Embed Size (px)

description

### Transcript of Ch2 Standards

Chapter 2 STANDARDS

Chapter 2STANDARDSStandard is a physical representation of a unit of measurement. A known accurate measure of physical quantity is termed as a standard.Dr. Mohd Ridzuan bin AhmadFaculty of Electrical EngineeringUniversiti Teknologi Malaysia81310 Skudai, Johor.2 Classification of Standards

Standards of Fundamental Quantities

Standards of Derived Quantities

StandardsINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsStandard of Paper Size

3Classification of StandardsINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsConsists of 4;

international standard primary standard secondary standard working standard

International Standards (ISs)

ISs are devices designed and constructed to specifications of an international forum

i.e. BSI, IEC, EU

4Classification of StandardsINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsInternational Standards (ISs) cont

ISs represents unit of measurement of various physical quantities to the highest possible accuracy that is attainable by use of advanced technique of production and measurement technologyPower Transformer comply toBS EN 60076-3:2001

5Classification of StandardsINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsInternational Standards (ISs) cont

ISs maintained systematically by actual measurement in physic definition such as mass, length, time, current etc

i.e the standard maintained by the inter. Bureau of weight & measure in Paris

ISs not available to ordinary user for purpose of day-to-day comparisons and calibration

6Classification of StandardsINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsPrimary Standards (PSs)

PSs are devices maintained by organizations/national laboratories in different part of the world or countries

PSs devices represent the fundamental, derive quantities and calibrated independently by absolute measurement

Main function of PS is to calibrate/check & certify secondary reference standards

PSs are not easily available to an ordinary user of instruments for verification/calibration or working standards

7Classification of StandardsINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsSecondary Standards (SSs)

Basic reference standards employed by industrial measurement laboratories

main function is the maintenance & periodic calibration of secondary standards against primary standards of the national standards laboratory/organization

SSs are freely available to the ordinary user of instruments for checking & calibrations of working standards

ESD protection area 8Classification of StandardsINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsWorking Standards (WSs)

high accuracy devices that commercially available, checked & certified against either the primary or secondary standard

i.e safety equipment in industry

9Classification of StandardsINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsRelationship between standard and accuracy PSIS SS WSDiagram Traceability Accuracy10Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsConsists of;

Mass

Time

Length

Absolute Ampere

Temperature

11Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsMass;

standard for mass is the International Prototype Kilogram (platinum-iridium cylinder)

kept at the Inter. Bureau of Weights & Measure in France

kilogram was originally defined as the mass of one liter of pure water at a temperature of 3.98 oC & standard atmospheric pressure (101 325 Pa).

12Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsMass; cont.

since 1998, the SI system defines the unit to be equal to the mass of the international prototype of the kilogram,

made from alloy of platinum & iridium of 39 mm height & diameter

official copies of the prototype kilogram are made available as national prototype (made in 1880s) & compared to Paris prototype (Le Grand Kilo) roughly every 10 years

13Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsTime;

60 seconds = 1 minute

3600 seconds = 1 hour

86.4 kilo seconds (86 400 seconds) = 1 day (in SI)

the factor of 60 may have influenced by Babylonians based on their 60 in counting system

the hour defined by Egyptians in term of rotation of earth as 1/24 of a mean of solar, 1/86400 of a mean solar day

14Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsTime; .cont

the second was defined in terms of the period of revolution of the Earth around the sun for a particular moment

the earths motion was describe in Newcombs Table of the sun that provides a formula for the motion of the sun at the epoch 1900 based on astronomical observations made during the 18 & 19 centuries

15Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsTime; .cont

the second thus defined as a fraction 1/35 556 925.9747 of the tropical year for 1900 January 0 at 12 hours ephemeris time (ET)

ET was defined as the measure of time that brings the observed positions of the celestial bodies into accord with the Newtonian dynamical theory of motion

the second was ratified by 11th General Conference on Weight & Measures in 1960

16Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsTime; .cont

2 astronomers at United States Naval Observatory (USNO) & National Physical Laboratory England determined the relationship between the hyperfine transition freq of the caesium atom & the ephemeris second

in 1967 the 13th General Conference on Weight & Measures defined the second of atomic time in SI as the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom (at 0 K)

Caesium atomic clock, 1955A walk through time

Ancient calendar depends on celestial bodies.First clock at EgyptMechanical clockCaesium Atomic clockWorld Time Zone. GMT20000 years ago16563500 BC1967Greenwich Mean Time (GMT)

19Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsLength: ..meter The meter is the unit of length in the International System of Units (SI)

It is one of the seven SI base units

m20Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsLength: ..meter

SI multiples of meter Multiple Name Symbol Multiple Name Symbol 100 meter m 101 decameter dam 101 decimeter dm 102 hectometer hm 102 centimeter cm 103 kilometer km 103 millimeter mm 106 megameter Mm 106 micrometer m 109 gigameter Gm 109 nanometer nm 1012 terameter Tm 1012 picometer pm 1015 petameter Pm 1015 femtometer fm 1018 exameter Em 1018 attometer am 1021 zettameter Zm 1021 zeptometer zm 1024 yottameter Ym 1024 yoctometer ym 21Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsLength: ..meter The origins of the meter go back to at least the 18th century

Some suggested defining the meter as the length of a pendulum having a half-period of one second;

others suggested defining the meter as one ten-millionth of the length of the Earth's meridian along a quadrant (one-fourth the circumference of the Earth).

22Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsLength: ..meter

In 1791, soon after the French Revolution, the French Academy of Sciences chose the meridian definition over the pendulum definition because the force of gravity varies slightly over the surface of the Earth, affecting the period of the pendulum.

23Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsLength: ..meter

in 1889, the 1st general conference on weights & measures (CGPM- Confrence Gnrale des Poids et Mesures) defined meter as a length of the International Prototype Meter, the distances between two finely scribed lines of platinum iridium bar when subject to certain specified conditions.

24Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsLength: ..meter definition of the meter was then replaced by CGPM in 1960 using a definition based upon a wavelength of krypton-86 radiation.

this definition was adopted in order to reduce the uncertainty with which the meter may be realized

to further reduce the uncertainty, in 1983 the CGPM replaced this latter definition by the following definition: The meter is the length of the path traveled by light in vacuum during a time interval of 1/299,792,458 of a secondKrypton a colourless and tasteless gas.2425Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsTemperature

is a physical property of a system that underlies the common notions of hot and cold; something that is hotter generally has the greater temperature

is one of the principal parameters of thermodynamics

26Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - StandardsTemperature

On the microscopic scale, temperature is defined as the average energy of microscopic motions of a single particle in the system per degree of Freedom

If no heat flow occurs, the two objects have the same temperature; otherwise heat flows from the hotter object to the colder object.

27Standards of Fundamental QuantitiesINSTRUMENT & ELECTRICAL MEASUREMENT - Stan