What is the practical use of a multimeter to measure resistance?
1. Coil type: 1. Two test leads, measuring both ends of the coil, the function is to determine whether the coil is disconnected. The buzzer will sound if there is continuity, but if there is no continuity, the buzzer will not sound.
2. Place one test lead at one end of the coil and the other at the ground wire. Measure the resistance of the coil to ground to determine whether the insulation layer of the coil is burned out.
3. Contacts, such as main contacts and auxiliary contacts of contactors and intermediate relays. Place the test leads at both ends to measure whether the contact is good and determine whether the contactor should be replaced.
4. Diode/transistor. By measuring its resistance, the diode has one-way conductivity, and you can determine the positive and negative poles of the diode. You can also determine whether the diode is good or bad and whether it has been reversely broken down.
Another function of the electrical barrier of the multimeter is to measure the conduction voltage of the diode. Select the gear to electrical blocking, and then switch it to measure the conduction voltage of the diode. The silicon tube is 0.7V and the germanium tube is 0.3V. To judge whether the quality of the diode is good or bad.
Note that when measuring resistance with a multimeter, the machine must not be electrified. The resistance can be measured only when the power is turned off.
The above is just the usage and function of the multimeter's electrical blocking.
The more commonly used one is the voltage block.
Use the voltage block of the multimeter, place one test lead on the place you want to measure, and place the other test lead on the reference point, usually the ground wire or metal case, to measure whether the voltage meets our design requirements. There is 220V between the live wire and the ground wire, and there is also 220V between the live wire and the neutral wire. The voltage between live wire and live wire is 380V. If these three numbers are met, it means that the incoming line is normal.
The ohm setting of the multimeter is the most commonly used setting.
When we repair or inspect circuits and components, we generally use the ohm level. To sum up, the commonly used functions or uses are as follows:
1. Measure the continuity of the circuit, such as the measurement of motor coils. In this case, many also use the buzzer mode to measure.
2. Measure the resistance of each circuit and component to calculate its power and other parameters. For example, for our electric furnace, its heating power can be calculated based on the measured resistance.
3. Used to judge the quality of components. For example, for a chip or component, the normal resistance between two pins is 100 ohms. In fact, it is 1K, or infinite. The component must be broken, such as the thermistor. Measure the resistance at both ends and if it does not change with temperature, then the thermistor should be broken.
4. Measure the actual resistance value of the resistor in the circuit. The color ring of some color ring resistors is not visible clearly. There are also some who verify the actual resistance value of the color ring resistor!
