One of the most basic functions of a DMM is to measure voltage. Testing the voltage is usually the first step in troubleshooting a circuit problem. If there is no voltage or if the voltage is too low or too high, the first thing to do is to fix the power problem before checking further.
The waveform of the AC voltage may be sinusoidal (sine wave) or non-sinusoidal (sawtooth, square, etc.). Many DMMs can display the "rms" (effective value) of AC voltage. The rms value is the value at which the AC voltage is equivalent to the DC voltage.
Many tables have an "average responding" function, which gives valid values when a pure sine wave is input. Such meters cannot accurately measure the rms value of non-sinusoidal waves. DMMs with true-rms function (true-rms) can accurately measure the true-rms value of non-sinusoidal waves.
The ability of a DMM to measure AC voltage is limited by the frequency of the signal being measured. Most DMMs can accurately measure AC voltages from 50 Hz to 500 Hz. However, the AC measurement bandwidth of the DMM can reach hundreds of kilohertz. For AC voltage and current, the frequency range should be consistent with the DMM specification.
DC voltage measurement
①Insert the black test lead into the COM jack and the red test lead into the V/Ω jack.
② Put the function switch in the DC voltage range V-range, and connect the test lead to the power supply to be tested (to measure the open circuit voltage) or the load (to measure the load voltage drop). The polarity of the red lead will be displayed on the display at the same time. superior.
③ Check the reading and confirm the unit
Note:
①If you don't know the voltage range to be measured, set the function switch to the maximum range and gradually decrease it.
②If the display only shows "1", it means over-range, and the function switch should be set to a higher range.
③“” means do not measure voltage higher than 1000V, it is possible to display higher voltage value, but there is a danger of damaging the internal circuit.
④When measuring high voltage, pay special attention to avoid electric shock.
AC voltage measurement
①Insert the black test lead into the COM jack and the red test lead into the V/Ω jack.
②Place the function switch in the AC voltage range V ~ range, and connect the test pen to the power supply or load to be tested. The test connection diagram is the same as above. When measuring AC voltage, there is no polarity display.
