Electrical Units of Measure Electrical Units of Measurement are used to express standard electrical units along with their prefixes when the units are too small or too large to express as a base unit
These electrical units of measurement are based on the International (metric) System, also known as the SI System with other commonly used electrical units being derived from SI base units. Sometimes in electrical or electronic circuits and systems it is necessary to use multiples or sub-multiples (fractions) of these standard electrical measuring units when the quantities being measured are very large or very small. The following table gives a list of some of the standard electrical units of measure used in electrical formulas and component values.
So to display the units or multiples of units for either Resistance, Current or Voltage we would use as an example: 1kV = 1 kilo-volt – which is equal to 1,000 Volts. 1mA = 1 milli-amp – which is equal to one thousandths (1/1000) of an Ampere. 47kΩ = 47 kilo-ohms – which is equal to 47 thousand Ohms. 100uF = 100 micro-farads – which is equal to 100 millionths (100/1,000,000) of a Farad. 1kW = 1 kilo-watt – which is equal to 1,000 Watts. 1MHz = 1 mega-hertz – which is equal to one million Hertz.
To convert from one prefix to another it is necessary to either multiply or divide by the difference between the two values. For example, convert 1MHz into kHz.
Well we know from above that 1MHz is equal to one million (1,000,000) hertz and that 1kHz is equal to one thousand (1,000) hertz, so one 1MHz is one thousand times bigger than 1kHz. Then to convert Mega-hertz into Kilo-hertz we need to multiply mega-hertz by one thousand, as 1MHz is equal to 1000 kHz. Likewise, if we needed to convert kilo-hertz into mega-hertz we would need to divide by one thousand. A much simpler and quicker method would be to move the decimal point either left or right depending upon whether you need to multiply or divide. As well as the “Standard” electrical units of measure shown above, other units are also used in electrical engineering to denote other values and quantities such as:
• Wh – The Watt-Hour
The amount of electrical energy consumed by a circuit over a period of time. Eg, a light bulb consumes one hundred watts of electrical power for one hour. It is commonly used in the form of: Wh (watt-hours), kWh (Kilowatt-hour) which is 1,000 watt-hours or MWh (Megawatt-hour) which is 1,000,000 watt-hours.
• dB – The Decibel,
The decibel is a one tenth unit of the Bel (symbol B) and is used to represent gain either in voltage, current or power. It is a logarithmic unit expressed in dB and is commonly used to represent the ratio of input to output in amplifier, audio circuits or loudspeaker systems. For example, the dB ratio of an input voltage (VIN) to an output voltage (VOUT) is expressed as 20log10 (Vout/Vin). The value in dB can be either positive (20dB) representing gain or negative (-20dB) representing loss with unity, ie input = output expressed as 0dB.
• θ – Phase Angle,
The Phase Angle is the difference in degrees between the voltage waveform and the current waveform having the same periodic time. It is a time difference or time shift and depending upon the circuit element can have a “leading” or “lagging” value. The phase angle of a waveform is measured in degrees or radians.
• ω – Angular Frequency
, Another unit which is mainly used in a.c. circuits to represent the Phasor Relationship between two or more waveforms is called Angular Frequency, symbol ω. This is a rotational unit of angular frequency 2πƒ with units in radians per second, rads/s. The complete revolution of one cycle is 360 degrees or 2π, therefore, half a revolution is given as 180 degrees or π rad.
• τ – Time Constant
, The Time Constant of an impedance circuit or linear first-order system is the time it takes for the output to reach 63.7% of its maximum or minimum output value when subjected to a Step Response input. It is a measure of reaction time.
And some More
quantities and units
quantities and units in physics
quantities and units in mechanics
quantities and units in nouns
quantities and units in context
quantities and units in nouns exercises
quantities and units of measurement
quantities and units in english language
quantities and units of radiation
quantities units and symbols in physical chemistry
quantities and units pdf
radiation quantities and units pdf
electrical quantities and units pdf
physical quantities and units pdf notes
fundamental quantities and units pdf
quantity and unit analogy pdf
derived quantities and their units pdf
physical quantities and their units pdf
100 derived quantities and their units pdf
physical quantities units and dimensions pdf
quantities and units in physics
quantities and units in mechanics
quantities and units of radiation
quantities and units of
physical quantities and units and formula
physical quantities and units and dimensional formula
derived quantities and their units and formula
physical quantities and their units and formulas
derived quantities formula and units
radiation quantities and units quizlet
physical quantities and units questions and answers
a level physics physical quantities and units questions
physical quantities and units of quantities
Comentarios