Multimeter True RMS - what it means and how to use it
For alternating current, its voltage is a changing waveform, usually we describe its voltage value is its effective value, such as what we call 220V power supply, its peak voltage of more than three hundred and ten volts, peak value of more than six hundred volts.
RMS: Defined by the heat (power), an alternating current through the resistor to produce heat and another direct current through the resistor, if the heat generated in the same time is equal, then the DC voltage value of the alternating current voltage of the effective value.
True RMS: the definition of the effective value is defined by the heat to define, but in the measurement instrument according to this method to the effective value of the voltage measurement is very difficult to achieve, so most of the voltage measurement instruments, such as multimeter to measure the voltage, the measurement method is not according to the effective value of the definition of the "heat" to carry out measurements, one class of multimeters to the Sine wave as a reference, through the peak of the sine wave for the root of two times the effective value of the relationship between the effective value to get (or through the average value to derive), this kind of method to get the effective value of the sinusoidal shape of the class of AC voltages is only correct, for other shapes of waveforms will produce bias. Another type of multimeter voltage value is the DC component, the fundamental waveform and the high harmonics of the RMS squared, this value is similar to the definition of the RMS value, the shape of the waveform is not required, in order to distinguish between this type of RMS value and the RMS value through the sinusoidal waveform instrumentation, in the measurement of instrumentation in the popular called the "true RMS value".
Root Mean Square (RMS) value: another name for the RMS value (which should be the true RMS value on the measuring instrument).
