ACV refers to AC voltage, DCV refers to DC voltage. The size and direction of the voltage change with time, called AC, such as AC 220V civil power, industrial power AC 380V and so on. The voltage size and direction does not change with time is called direct current, such as dry batteries, batteries. The basic principle of a multimeter is to use a sensitive magnetoelectric DC ammeter (microammeter) as the watch head. When a small current passes through the watch head, there is a current indication. However, the meter head can not pass a large current, so it is necessary to shunt or buck some resistors in parallel and series on the meter head, so as to measure the current, voltage and resistance in the circuit. Precautions for multimeter use:
1, familiar with the meaning of each symbol on the dial and the main role of each knob and selection switch.
2. Mechanical zeroing should be carried out before testing.
3, according to the type and size of the measured, select the gear and range of the transfer switch to find out the corresponding scale line.
4, in the measurement of current, voltage, can not be charged change range.