How to reduce errors in detecting AC voltages with using a pointer multimeter?
First, the characteristics of detecting AC voltage with an pointer multimeter. When the AC voltage is detected by using the pointer multimeter, the internal circuit of the pointer multimeter converts the AC voltage rectify to the DC voltage first, so the error of DC conversion will be formed. It will also be affected by the frequency characteristics of the rectifier. The rated frequency used in the general pointer multimeter AC voltage stopper is usually within the 45~1000Hz range. If the frequency of the detection voltage is higher than the permitted frequency, due to the existence of the rectifier (generally using rectifier diode) junction capacitor, The reverse voltage leakage rectifier diode, which will reduce the rectifier effect, the higher the frequency, the more serious the impact. If the frequency range of the detected voltage exceeds the rated value and is less than 10kHz, the measurement of the AC voltage can be carried out, but the error of the detected data is very large. In addition, when the AC voltage is low, the nonlinear distortion of rectifier diode will also cause the detection error.
Second, the method of reducing the error in detecting AC voltage. When the AC voltage is detected by using the pointer multimeter, it should be noted that the AC 10V shift of the pointer multimeter is usually calibrated separately. The pointer multimeter is only suitable for detecting sinusoidal voltage whose waveform distortion is less than 2%. If the detected sinusoidal waveform distortion is more than 2% or all kinds of non-sinusoidal wave, the detection error will be larger because of the influence of waveform. When using the AC voltage of an exponential multimeter to block the detection of the filament voltage of the color picture tube, since the voltage is usually a line pulse signal voltage, its effective value is 6.3 V, and the peak to peak value is about 30 V, Therefore, it is difficult to detect these two voltages by using an pointer multimeter, and only AC voltage shift or dB shield can be used to judge whether the voltage is available or not.
This article is from Allicdata Electronics. Reprinted need to indicate the source.