In the usual measurement work, the correct use of the multimeter can quickly and accurately determine the fault location, and can prevent damage to the electrical equipment and the multimeter itself. Here are the classic formulas used by the multimeter, and the usage of each formula is explained in detail. , and friends in need refer to it.
How to use the multimeter
1. When measuring, look at the block first, and do not measure without looking.
Every time you pick up the test leads to prepare for measurement, you must check again whether the measurement category and range selection switches are in the correct positions. In order to ensure the safety of the measurement process, it is necessary to develop a good habit of inspection and confirmation.
2. Do not shift the gear during measurement, after the measurement, shift the neutral gear
During the measurement process, do not turn the selection knob arbitrarily, especially when measuring high voltage (such as 220V) or large current (such as 0.5A), so as to avoid arcing and burning out the contacts of the transfer switch. After the measurement is completed, you need to turn the range selection switch to the "?" position.
3. The dial should be level and the reading should be aligned
When using the multimeter, it should be rotated horizontally, and the line of sight should be facing the needle when reading.
Detailed explanation of classic formulas for correct use of multimeters
4. The range should be appropriate, and the needle is more than halfway off.
Select the range, if it is impossible to estimate the measured size in advance, it is best to choose a larger range, and then gradually change to a smaller range according to the deflection angle, until the pointer is deflected to about 2/3 of the full scale.
5. Test R is not charged, test C is discharged first
It is strictly forbidden to measure resistance when the circuit under test has a point. When checking large-capacity capacitors on electrical equipment, the capacitors should be short-circuited and discharged before measurement.
6. Zero adjustment first when measuring R, and zero adjustment is required for shifting
When measuring the resistance, first turn the switch to the electric block, short-circuit the two test leads, and turn the "Ω" zero potentiometer to make the pointer point to zero ohms before measuring. The ohmic zero should be readjusted every time the electrical barrier is replaced.
7. The black and negative should be remembered clearly, and the black in the table should be connected to "+"
The red test lead is the positive electrode, and the black test lead is the negative electrode, but the black test lead is connected to the positive electrode of the internal battery.
8. The measurement I should be connected in series, and the measurement U should be connected in parallel
When measuring current, connect the multimeter in series with the circuit under test; when measuring voltage, connect the multimeter in parallel with both ends of the circuit under test.
9. The polarity is not reversed, and one hand becomes a habit
When measuring current and voltage, special attention should be paid to the polarity of the red and black test leads not being reversed. Be sure to develop the habit of one-handed operation to ensure safety.
