Is the true effective value of a multimeter important
A regular pointer multimeter or digital multimeter has a frequency range for measuring high frequency voltage and current. Beyond the frequency range, they cannot accurately reflect the true RMS of high-frequency waveforms. You can take a look at the technical specifications of your multimeter and it will be clear.
What is True RMS?
Only true RMS meters can accurately measure voltage/current. The calculation method for measuring AC signals using its average value meter is: the average value of the measured values × 1.11=corrected to a valid value. The calculation method for measuring AC signals with True RMS meters is: root mean square algorithm=True RMS. For pure sine waves, both true RMS and mean value meters can accurately measure, but for non sine waves such as square, triangular, and serrated waves, only true RMS meters can accurately measure. Nowadays, many electronic loads that have undergone frequency changes are non sine waves, and having a true RMS multimeter is necessary to accurately measure the correct value.
How to measure the grounding voltage of precision equipment with a multimeter
Precision equipment must have an absolutely good grounding. If various power disturbances do not affect the accuracy of precision equipment, the conventional method is to use a megohmmeter to shake the ground resistance. However, when testing electronic precision equipment, a megohmmeter cannot be used because the high voltage generated by the megohmmeter can break through the components of precision electronic equipment, so a multimeter is also needed, When the equipment is static, I usually use a multimeter to measure the resistance between the grounding terminal and the standard ground using the X1 position of the pointer meter. When the equipment is dynamic, I directly use the DC voltage range of the multimeter to measure the voltage between the equipment ground and the standard ground. Generally, when the equipment generates grounding voltage, this voltage is not the standard DC voltage. It is recommended to use a pointer multimeter, which can roughly monitor the grounding voltage status of the equipment at different operating states, For example, when precision equipment is working, if a frequency converter or welding machine is activated in the circuit, it will cause high-order harmonic interference to the precision instrument. At this time, using a pointer table is more intuitive, while the number table will pop up for 8 and 0, and the trend cannot be seen.
