What is True RMS Multimeter?

True RMS multimeter (RMS = square root of squared averages) is the name given to multimeters that can measure alternating current (AC) or AC voltage:

  1. True-RMS digital multimeters
  2. Average reactive digital multimeters
  3. Oscilloscope

Only the first two tools are widely used, and both can accurately measure waveforms in the form of standard (pure AC) sine curves.

However, the True RMS measuring device is widely preferred because only this device can accurately measure AC waveforms that are both in the form of a sine curve and not in the form of a sinus curve.

  • Waves in the form of sinus curve :Pure, unsorthical, symmetrical transition between the top and bottom points.
  • Waves that are not in the form of a sine curve: Waves with distorted, irregular patterns: Ripples, pulses, squares, triangles, saw-tooth waves, and other scattered or angled waves.

How is RMS Calculated?

You can get detailed information from this article we have created for RMS account. As mentioned earlier, RMS = is the square root of the squared averages.Although the formula is somewhat difficult to grasp, RMS mainly calculates the equivalent direct current (DC) value of an AC waveform. More technically, it determines the "effective" or DC heat value of any AC waveform.

An average reactive meter uses average field math formulas to accurately measure waves in the form of pure sinus curves. It can measure waves that are not in the form of a sinus curve with ambiguous accuracy.

A more complex True RMS meter can accurately measure both pure waves and more complex, non-sinus curve waves. Waveforms can be corrupted by nonlinear loads, such as variable-speed drives or computers. The calculations of an average meter that tries to measure broken waves can be 40% lower or 10% higher.