Frequently Asked Questions and Precautions for Using Multimeters

For electrical maintenance workers, we must pay attention to the following things when using a multimeter:
1. Voltage below 36V is a safe voltage. When measuring voltage higher than 36V DC or 25V AC, check whether the test leads are in reliable contact and whether they are correctly connected. , whether the insulation is good, etc. to avoid electric shock.
2. When changing the function and range, the test leads should leave the test point. Select the correct function and range when testing, and be careful of misoperation.
3. For DC voltage measurement, first turn the range switch to the corresponding DCV range, and then connect the test lead across the circuit under test. The voltage and polarity of the point connected to the red test lead are displayed on the screen.
4. For AC voltage measurement, first turn the range switch to the corresponding ACV range. Then connect the test leads across the circuit under test.
5. For DC current measurement, first turn the range switch to the corresponding DCA position, and then connect the meter to the circuit under test.
6. For AC current measurement, first set the range Turn the switch to the corresponding ACA position, and then connect the meter to the circuit under test.
7. Resistance measurement, turn the range switch to the corresponding resistance range, and connect the two test leads across the resistance to be measured.
8. Capacitance To measure, turn the range switch to the corresponding capacitance range, connect the test pen across the capacitor under test, and measure at both ends. Pay attention to the polarity if necessary.
9. Test the diode and continuity, and set the range switch. The red meter is connected to the positive electrode of the diode, and the black test lead is connected to the cathode of the diode. When testing the continuity of the line, connect the test leads to both ends of the line to be measured. If the buzzer sounds, the circuit is connected, otherwise the circuit is disconnected.
10. Tube amplification To measure, set the range switch to the hFE position, determine whether the transistor to be measured is NPN or PNP, and insert the emitter, base, and collector into the corresponding holes.