Operation and Maintenance of General Multimeters
Multimeters come in many structural forms with different layouts of knobs and switches on the panel. Therefore, before using a multimeter, you should carefully learn and get familiar with the function of each component, and distinguish the measurement range corresponding to each scale on the dial. Special attention must be paid to the proper use of the multimeter, as most multimeter faults are caused by improper operation. Proper use of a multimeter is actually the best maintenance for it. In addition, only correct operation can minimize measurement errors.
Place the multimeter horizontally before use and check whether the pointer is at the zero position. If not, adjust the mechanical zero adjustment screw in the middle of the meter to align the pointer with zero. Connect the lead of the red test probe to the red terminal or the jack marked with "+", and the lead of the black test probe to the black terminal or the jack marked with "-". Rotate the selector switch to the required position according to the measurement target. For example, when measuring AC voltage, turn the selector switch to the corresponding range. Some multimeters have separate knobs for function selection and range switching. In use, first turn the function selector knob to the required gear for the measured object, then turn the range knob to the corresponding position. Pay close attention to function selection; failure to do so may lead to serious consequences.
Precautions:
(1) Do not measure insulation resistance during thunderstorms or near high‑voltage equipment. Measurements can only be carried out when the equipment is de‑energized and free of induced electricity.
(2) No personnel shall work on the equipment under test during the megger test.
(3) The megger test leads must be separated and not twisted together.
(4) Do not touch the equipment before the megger stops rotating or the equipment under test is fully discharged. Do not touch the metal part of the leads when disconnecting the wiring.
(5) Discharge large‑capacitance equipment after measurement.
