Briefly describe the basic operation method of measuring resistance with a multimeter
1. First connect the test leads. The multimeter can be either a pointer or a digital display. The red test lead is inserted into the VΩ position, and the black test lead is inserted into the COM terminal to ensure that the multimeter is normal.
2. Rotate the multimeter gears. When measuring resistance, use the resistance gear. If you are not sure about the resistance value, you should first set the range switch to the maximum value, and then switch from the large range to the small range, so that the meter pointer indicates the full range. Just above 1/2 of the scale. After selecting the appropriate magnification level, touch the two test leads so that the pointer points to the zero position. If the pointer deviates from the zero position, the "zero adjustment" knob should be adjusted to return the pointer to zero to ensure accurate measurement results.
3. Connect the two sections of the resistor. Connect the test leads casually. There is no positive or negative distinction. Make sure the contact is good.
4. Read the data displayed by the multimeter. If no data appears on the multimeter, it may be that the resistor is broken. Of course, another possibility is that the range is not enough, so change the range.
5. Increase the measuring range. If there is no data, it only means that the resistor is broken. If there is data output data, pay attention to the unit of the gear.
Basic principles of multimeter:
A sensitive magnetoelectric DC ammeter (microampere meter) is used as the meter head. When a small current passes through the meter, there will be a current indication. However, the meter head cannot pass large current, so some resistors must be connected in parallel or series with the meter head to shunt or reduce the voltage, so as to measure the current, voltage and resistance in the circuit.
Precautions for using a multimeter:
1. Before using the multimeter, you should perform "mechanical zero adjustment", that is, when there is no electric quantity being measured, the multimeter pointer should point at the zero voltage or zero current position.
2. When using the multimeter, do not touch the metal part of the test lead with your hands. This can ensure the accuracy of the measurement on the one hand and personal safety on the other hand.
3. When measuring a certain amount of electricity, you cannot change gears while measuring, especially when measuring high voltage or large current, you should pay more attention. Otherwise, the multimeter will be damaged. If you need to change gears, you should disconnect the test leads first, and then measure after changing gears.
4. When using the multimeter, it must be placed horizontally to avoid errors. At the same time, attention should also be paid to avoiding the influence of external magnetic fields on the multimeter.
5. After using the multimeter, the transfer switch should be set to the maximum AC voltage range. If it is not used for a long time, the battery inside the multimeter should also be taken out to prevent the battery from corroding other components in the meter.
