NPLC

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NPLC (Abbreviation for Number of Power Line Cycles or Net Power Line Cycles ) is a term from measurement technology and describes the accuracy with which a voltage or current is displayed by a measuring device (e.g. a multimeter ). It indicates the number of network cycles over which a measuring device integrates before it displays a measured value .

Basics

Alternating voltages and currents have a periodic course, which is described with its frequency in Hertz . The measured values, shown as a curve over time, usually have the shape of a sine curve ; Other curves ( rectangular shape , sawtooth curve ) are also possible. Voltages tapped at points on this curve therefore do not provide any information about the rms value of the alternating voltage, but only the value that can be determined on the curve at the time of measurement. In order to determine the effective value, several measured values ​​must therefore be integrated. The number of these measured values ​​in relation to the duration of an oscillation period is indicated with the designation NPLC.

Example: If a multimeter measures a voltage above 50 NPLC, the voltage is averaged over 1 second and then displayed (at a mains frequency of 50 Hz, i.e. a period of 0.02 sec).

A high NPLC "calms" the measured value and eliminates the noise , this is paid for by the longer duration of the measurement. A low NPLC leads to rapidly changing, fluctuating measured values. If the variable to be measured is disturbed by the mains frequency, an NPLC ≤ 1 determines unreliable measured values, since a whole (disturbance) voltage cycle is no longer evaluated.

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