How to Use a Multimeter to Measure AC and DC Voltage
1. Measure first by looking at the gear, don't measure without looking
Every time you pick up the probe to prepare for measurement, be sure to double check if the measurement category and range selection switch are in the correct position. For safety reasons, it is necessary to develop this habit.
2. Measure without shifting gears, and after measuring, shift to neutral gear
During measurement, the selection knob should not be arbitrarily turned, especially when measuring high voltage (such as 220V) or high current (such as 0.5A), to avoid generating arcs and burning out the switch contacts. After the measurement is completed, the range selection switch should be turned to the "?" position.
3. The dial should be level and the reading should be correct
When using a multimeter, it should be rotated horizontally and the reading should be directed directly towards the needle.
4. The range should be appropriate, and the needle should be too far off center
Choose a range. If it is not possible to estimate the size of the measured object in advance, try to choose a larger range and gradually switch to a smaller range based on the deflection angle until the pointer deviates to about 2/3 of the full scale.
5. Test R without charging, discharge C first
It is strictly prohibited to measure resistance in the presence of a point on the circuit being tested. When checking large capacity devices on electrical equipment, the short circuit should be discharged first before measuring. Click to download massive engineering materials for free
6. To test R, adjust it to zero first, and to shift gears, adjust it to zero
When measuring resistance, first turn the conversion switch to the resistance position, short circuit the two probes, turn the "Ω" zero potentiometer to make the pointer point to zero, and then measure. Every time the resistance gear is changed, the zero point of the ohm should be readjusted.
7. Remember the black negative and connect it with a "+" in the table
The red probe is the positive pole, and the black probe is the negative pole, but the resistor is blocked and the black probe is connected to the positive pole of the internal battery.
8. The measurement of I should be in series, and the measurement of U should be in parallel
When measuring current, a multimeter should be connected in series with the circuit being tested; When measuring voltage, a multimeter should be connected in parallel at both ends of the circuit being tested.
9. Polarity not reversed, one handed habit
When measuring current and voltage, special attention should be paid to the polarity of the red and black probes not being reversed, and the habit of one handed operation must be developed to ensure safety.
