October 31, 2023
The multimeter is an essential troubleshooting tool for electrical maintenance personnel. "One person, one hit, one meter" clearly tells us that basic requirements for electricians are: electrician + electric pen + multimeter. This is an electrician. In daily maintenance, a multimeter plays an extremely important role.
But do you know how to use a multimeter? Master these 14 tips and get twice result with half effort.
1. Before using multimeter, you must first perform a "mechanical zero adjustment";
2. Do not touch metal part of probe with your hands during measurement process, which not only ensures measurement accuracy, but also ensures personal safety;
3. In difficult conditions, it is necessary to pay attention to influence of an external magnetic field on multimeter;
4. To improve measurement accuracy, try to keep multimeter needle in middle position when measuring. The measuring range must be appropriate, and pointer must be moved more than half. Select a range. If you cannot estimate size of measured object in advance, you should try to select a larger range, and then gradually move to a smaller range according to deflection angle until pointer deviates about 2/3 of deflection angle. full scale;
5. When using a multimeter to test components with positive and negative polarity, such as transistors and electrolytic capacitors, pay attention to polarity relationship. Black minus must be written clearly, and black in table is associated with "+". The red lead is positive pole and black lead is negative pole, but electrical box connects black lead to positive pole of internal battery;
6. If multimeter needs to change gears, first disconnect test leads, and then measure after changing gears. Do not change gear during measurement and set gear to neutral after measurement. During measurement, selection knob must not be moved arbitrarily, especially when measuring high voltage (for example, 220 V) or high current (for example, 0.5 A), so as not to form an arc and burn contacts of transfer switch. After measurement is completed, range selection switch must be moved to “•” position;
7. When measuring resistance, a zero adjustment is required at each gear change. Replace battery with a new one if it cannot be adjusted to zero. To measure R, first set it to zero and then change gear. When measuring resistance, first turn switch on electrical box, short-circuit two test leads, turn "Ω" to zero potentiometer, and set pointer to zero ohm before measuring. Each time electrical barrier is replaced, zero point of ohmic resistance must be re-adjusted;
8. After using multimeter, transfer switch should be set to maximum transfer of AC voltage;
9. If you do not use it for a long time, please take out battery inside multimeter to prevent battery corrosion of other components in multimeter;
10. Check block first when measuring and measure without looking. Every time you pick up a test lead and prepare to make a measurement, be sure to check that measurement category and range select switch is in correct position. For safety, this habit must be developed;
11. The dial must be level and reading must be level. When using a multimeter, it must be turned horizontally, and line of sight must face arrow when reading;
12. When measuring R, it does not charge, and when measuring C, it first discharges. It is strictly forbidden to measure resistance when circuit under test has points. When testing high-capacity capacitors on electrical equipment, capacitors should be short-circuited and discharged before measurement;
13. Test I should be connected in series and test U in parallel. When measuring current, multimeter must be connected in series in circuit under test; when measuring voltage, multimeter must be connected in parallel at both ends of circuit under test;
14. If polarity does not change, one hand becomes a habit. When measuring current and voltage, special care should be taken to ensure that polarity of red and black test leads are not reversed, and it is necessary to develop habit of working with one hand to ensure safety.
The tricks of multimeter are simple and straightforward.