Three situations of the effective value of the multimeter
Meaning of valid values in multimeter
For alternating current, its voltage is a changing waveform, and its voltage value is usually described as its effective value. For example, the 220V power supply has a peak voltage of more than 310 volts and a peak-to-peak value of more than 600 volts.
1. Effective value: It is defined by heat generation (power). A certain alternating current generates heat through a resistor and another direct current passes through the resistor. If the heat generated in the same time is equal, then the direct current voltage value is this alternating current. The effective value of the voltage.
2. True RMS: The definition of RMS is defined by heating, but it is difficult to measure the RMS voltage in this way in measuring instruments, so in most voltage measuring instruments, such as multimeters measure voltage, The measurement method is not measured according to the "heat" defined by the effective value. One of the multimeters uses the sine wave as a reference, and the effective value is obtained by the relationship between the peak value of the sine wave and the effective value twice the root sign (or Derived by the average value), the effective value obtained by this method is only correct for the AC voltage of the sinusoidal waveform, and there will be deviations for other shapes of the waveform.
Another type of multimeter voltage value is obtained by the square of the effective value of the DC component, the fundamental wave, and each higher harmonic. This value is similar to the definition of the effective value, and there is no requirement for the shape of the waveform. The sine wave is different from the effective value instrument, which is called "true effective value" in the measuring instrument.
3. Root mean square value: Another name for effective value (should be true effective value on the measuring instrument).
