How to Use a Multimeter to Find Problems
Multimeters, also known as multiplexers, multimeters, triple meters, and multimeters, are indispensable measuring instruments in power electronics and other departments, generally aimed at measuring voltage, current, and resistance. Multimeters are divided into pointer multimeter and digital multimeter according to their display mode. It is a multifunctional and multi range measuring instrument. Generally, a multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance, audio level, etc. Some can also measure AC current, capacitance, inductance, and some parameters of semiconductors (such as β） Etc.
How to use a line multimeter
Under live conditions, use AC voltage or DC voltage according to the situation! Use resistance gear to detect circuit paths and short circuits without points!
The multimeter has a beep stop, which means using two probes to measure the same wire. If there is a short circuit, there will be no response. If there is a circuit, there will be a beep sound. Sometimes, when the device itself is grounded poorly and the shell is live, the red probe of the multimeter can be placed on the black label of the shell to directly contact the ground. The strength of the shell leakage current can be measured by connecting it to the circuit in series for the rest of the work.
To check for circuit leakage, a megohmmeter (megger) should be used, as the voltage of the multimeter is lower (9V) and the voltage of the megohmmeter is higher (500V). Because the working voltage of the circuit is 220V, it is difficult to diagnose circuits with insignificant leakage. To use a digital meter to check for circuit leakage, you first need to cut off the power supply, discharge the circuit, and measure it with a resistance level of 2M. The normal display is 1 (infinite).
Measuring whether the circuit is in a connected state can be measured using a multimeter's ohm range. When measuring, it is necessary to select a range where the meter pointer is close to 0 ohms of deflection. If the circuit is in a circuit, one end (A end) of the circuit should be connected to a multimeter (red lead) at 100 ohms, and the black lead should be connected to the other end (B end) of the circuit to be measured. If the measured result is zero, it indicates that the circuit is connected, also known as a path. Only a path can current flow through the circuit; If the multimeter ohmmeter pointer at the A to B end of the circuit is not close to zero ohms, the circuit is already in an open circuit state, and disconnection is called an open circuit or an open circuit.
