Measurement of voltage on a digital multimeter
1. Measurement of DC voltage, such as batteries, walkman power supplies, etc. Firstly, insert the black probe into the "com" hole and the red probe into the "V Ω" hole. Select the knob to a range larger than the estimated value (note: the values on the dial are all the maximum range, "V -" represents the DC voltage range, "V~" represents the AC voltage range, and "A" is the current range), then connect the probe to the power supply or both ends of the battery; Maintain stable contact. The numerical value can be directly read from the display screen. If it shows "1.", it indicates that the range is too small, so a large range needs to be added before measuring industrial appliances. If a "-" appears to the left of the value, it indicates that the polarity of the probe is opposite to the actual power supply polarity, and the red probe is connected to the negative pole.
2. Measurement of AC voltage. The probe socket is the same as the measurement of DC voltage, but the knob should be turned to the required range at the AC gear "V~". There is no positive or negative distinction in AC voltage, and the measurement method is the same as before. Whether measuring AC or DC voltage, attention should be paid to personal safety and do not touch the metal part of the pen with your hands casually.
Precautions for using a digital multimeter
If it is not possible to estimate the magnitude of the measured voltage or current in advance, it should be measured once at the highest range, and then gradually reduce the range to the appropriate position depending on the situation. After the measurement is completed, the range switch should be turned to the high voltage range and the power should be turned off.
When the instrument is at full range, only the digit "1" is displayed at the highest position, and all other digits disappear. In this case, a higher range should be selected.
When measuring voltage, a digital multimeter should be connected in parallel with the circuit being tested. When measuring current, it should be connected in series with the circuit being tested, and there is no need to consider positive or negative polarity when measuring direct current.
When using the AC voltage range to measure DC voltage or the DC voltage range to measure AC power, the display screen will display "000" or the number on the low position will jump.
5. It is prohibited to change the range when measuring high voltage (above 220V) or high current (above 0.5A) to prevent arc generation and burning of switch contacts.
