Glossary of Terms
Units of Measurement
AC
- The abbreviation for Alternating Current. An electric current that reverses its polarity at regular intervals.
Amp
- The abbreviation for Ampere and the unit of measurement of current. The symbol is "A"
Apparent Power
- Measured in VA and is used in AC circuits when the load is not purely resistive having an inductive or capacitive nature.
Crest Factor
- The Ratio of the peak value divided by the r.m.s. value. With a true Sine Wave the Crest Factor is equal to the square root of 2 or 1.414
DC
- The abbreviation for Direct Current. An electric current that has a constant polarity.
K
- The symbol of Kilo meaning 1000 (e.g. 1KW = 1000 Watts)
Peak
- The highest instantaneous value found on any part of a waveform.
PF
- The abbreviation for Power Factor. The Power Factor is defined as Real Power divided by Apparent Power.
Potential Difference
- The difference of potential expressed in Volts measured between two points.
R.M.S.
- The abbreviation of Root Mean Square. Defined as the square root of the arithmetic mean of the squares of a set of values of a waveform. This value is used to provide an effective value of any AC waveform that is comparable to a DC value. With a "true" sine wave the r.m.s. value is 0.707 of the peak (or the peak is 1.414 x the r.m.s.).
Real Power
- Measured in Watts and is used in DC circuits and AC circuits when the load is resistive.
VA
- The abbreviation for Volt Amp and is the product of multiplying Voltage and Amperage. See Apparent Power.
VAC
- The Voltage of an Alternating Current.
Voltage
- The Electromotive Force (EMF) or Potential difference. The unit of measurement is the Volt. The symbol is 'V"
Watt
- The unit of measurement of power. One Watt occurs when the potential difference in a circuit is one Volt and a current of one Amp flows. See Real Power.
VDC
- The Voltage of an Direct Current.
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