Multimeters with true RMS
prices on 10 models True RMS
— this function allows the device to measure power as accurately as possible (see "Measurements") when working with alternating current. Without True RMS, accurate power measurement is only possible if the voltage is a perfect sine wave. However, in fact, such an perfect is rare, and due to distortions in the network, the measurement error in the classical way can reach 40 – 50%. True RMS models do not have this disadvantage: such a device will determine the average (rms) AC power, regardless of whether it corresponds to a perfect sine wave or not.