Descriptive units of current and voltage

There are various ways of reporting the amount (amplitude or magnitude) of a current or voltage.

For example, peak amplitude is the height of a wave from zero to either the highest positive point, or the lowest negative point. However, it is useful to report current amplitude as an average. At a 50% duty cycle (1:1 mark:space ratio) a pDC waveform will have an average current that is always half of the peak current. For different duty cycles, the average and peak current can be calculated.

For AC, if the proportion of time the wave spends above zero is equivalent to the time spent below zero, the mathematical average will be zero and meaningless. Instead, the ‘root mean square’ (RMS), or ‘effective’, current can describe an AC wave.

Abattoir personnel must always report the appropriate descriptive units when recording the electrical parameters used in a stunner (eg ‘RMS’ for AC, ‘average’ for pDC and the constant amplitude value for DC).

Next: Summary of electrical terminology