Multimeter Frequently Asked Questions
What is the difference between an Average Response Multimeter and a True RMS Multimeter?
The average response multimeter measures AC signals by multiplying the average value by the waveform factor calibrated to the RMS value, while the true RMS algorithm for measuring AC signals is the root-mean-square algorithm, which is accurate for pure sinusoidal waveforms, regardless of whether it is a true RMS or an average response meter, but for distorted waveforms or typical non-sinusoidal waveforms such as square, triangular, or jagged waveforms, only a true RMS meter can accurately measure them.
What is a low pass filter?
A low-pass filter is a circuit that allows low-frequency signals to pass through and attenuates high-frequency signals. The built-in low-pass filter intercepts signals higher than 1 KHz and attenuates signals lower than 1 KHz and higher than 100 Hz, allowing for the measurement of the fundamental signals of a frequency converter or other inverter.
What is the AC bandwidth of a multimeter?
Bandwidth is the range of AC frequency that a digital multimeter can measure within the accuracy paradigm. It is not a function of frequency measurement, but reflects the ability of AC frequency response. If the frequency exceeds the AC bandwidth of the multimeter, the multimeter will not be able to measure the AC value correctly within the frequency response range. Therefore, a wide AC bandwidth plays an important role in a high-performance digital multimeter.
How can a multimeter eliminate the effect of line resistance with the REL function?
When we use a multimeter to measure resistance, any pair of test wires will generate a certain amount of line resistance, and to measure accurately, we need to test the line resistance in advance and then manually subtract it after the test is completed. In fact, the REL function in the multimeter can help us to eliminate the influence of line resistance automatically, after the function is turned on, it will automatically record this value and display zero, and at the same time, it will automatically subtract this value in any measurement, so as to get a more realistic resistance value.
Why can't my multimeter return to zero when it is turned to millivolt?
This is because digital multimeters have a high input impedance, typically above the megohm level, and are very capable of driving a voltage source. In the case of an open-circuit meter, at smaller voltage levels such as DC millivolt level mVDC, AC millivolt level mVAC, the induced voltage generated by the electromagnetic wave of the surrounding environment can be easily detected by the multimeter, and the display will not be zero, which is normal. If the multimeter stick is shorted to form a circuit, the multimeter reading will slowly tend to zero.
