The Control Techniques Drives and Controls Handbook
This handbook contains technical information for practicing drive and electrical engineers, covering the technology underlying drives, motors, and control units and modern practical applications.
TABLE OF CONTENTS The Control Techniques Drives and Controls Handbook
Appendix B: Symbols and Formulae
B1 SI UNITS AND SYMBOLS
The following formulae are based on the International System of Units, known as SI (Systeme Internationale d'Unites) which is used throughout this book. SI was adopted in February 1969 by a resolution of the CGPM (Conference Generale de Poids et Mesures) as ISO Recommendation R1000.
A base unit exits for each of the dimensionally independent physical quantities: length, mass, time, electric current, thermodynamic temperature and luminous intensity. The SI unit of any other quantity may be derived by appropriate simple multiplication or division of the base units without the introduction of numerical factors.
The system is independent of the effects of gravity, making a clear distinction between the mass of a body (unit of mass = kilogram) and its weight, i.e. the force due to gravity (unit of force = Newton).
Example:
A force of 1 N acting on a mass of 1 kg results in an acceleration of 1 m s ?2.
Conversion factors from non SI units to SI units are to be found in Appendix C.
SI BASE UNITS
| Quantity | Unit symbol | Unit name |
|---|---|---|
| Length | m | meter |
| Mass | kg | kilogram |
| Time | s | second |
| Electric current | A | Ampere |
| Temperature | K | Kelvin |
| Luminous intensity | cd | candela |
DECIMAL MULTIPLES AND SUBMULTIPLES
| Factor | Prefix | Symbol |
|---|---|---|
| 10 12 | tera | T |
| 10 9 | giga | G |
| 10 6 | mega | M |
| 10 3 | kilo | k |
| 10 2 | hecto | h |
| 10 | deca | da |
| 10 ?1 | deci | d |
| 10 ?2 | centi | c |
| 10 ?3 | milli | m |
| 10 ?6 | micro | ? |
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