root mean sqaure measurement

The RMS value is the square root of the root mean square(RMS) and represents the actual average voltage, current or power values that occur.

To measure the RMS value, it is necessary to square, average and take the square root. This can be done, for example, with electromechanical movements, which are so inertthat the average value is displayed.

With a moving iron instrument, the true RMS value is measured only at low frequencies. The use of thermo-transducers for RMS measurements up to 1 GHz solves the frequency problem. The temperature of the thermistor is proportional to the square of the current. By taking the square root, the true RMS value is obtained.

To measure the RMS value, digital measuring devices such as digital multimeters are preferred today, which are equipped with integrated circuits or microcontrollers to form the true RMS value.