The true RMS value is measured independently of an input signal waveform.
Because of the use of two thermocouples, the non linearity problem is avoided. Here the meter indication is linearly proportional to the input signal under measurement.
There are some disadvantages of true RMS reading voltmeter which are given below,
The crest factor causes the limitation on the true RMS responding voltmeter for the measurement of highly non linear waveforms.
Since the thermocouples are used, the response of the system becomes sluggish.
Because of the thermal behaviour of the system, the accuracy is affected.
