Glossary

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 capacative 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 (eg. 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.

Pottential 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 compariable 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 Ampage. 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 pottential difference in a circuit is one Volt and a current of one Amp flows. See Real Power.

VDC

The Voltage of an Direct Current.