Learn to use multimeter to find faults
It is the most basic function of multimeter to check short circuit, open circuit and leakage. Let's talk about it in detail below. How to check with multimeter?
Method of checking whether the wire is short-circuited by multimeter
Wire short circuit: it means that the live wire and the neutral wire are connected together, so we call it wire short circuit.
The multimeter judges whether the live wire and the zero wire are short-circuited. We should use the buzzer of the multimeter. In case of power failure, first we put the red probe on the live wire and the black probe on the zero wire. If there is a buzzer, it is proved to be on. If the live wire is on, it proves that the wire is short-circuited, and the multimeter does not respond, which proves that it is not feasible. If the live wire is blocked, it proves that the wire is not short-circuited.
Remarks: To check the short circuit with a multimeter, first cut off the power, and disconnect the live wire and neutral wire from the load.
Method of checking whether the wire is open by multimeter
Wire open circuit: refers to that the wire is blocked and there is a breakpoint in the middle of the wire, which is also called open circuit.
The multimeter judges whether the wire is open, and it also uses the buzzer of the multimeter to put the red and black probes at the two ends of the wire respectively. If there is a buzzer, it is proved to be open, and if the multimeter does not respond, it is proved to be broken, that is, the wire is open.
Remarks: Use a multimeter to judge whether the wire is open, and measure the break point of the wire.
Method of judging whether the wire leaks by multimeter
Electric wire leakage: it refers to the connection between live wire and ground wire, or the connection between zero wire and ground wire, which is called electric leakage. The connection between live wire and ground wire is live wire leakage, and the connection between zero wire and ground wire is zero wire leakage.
Leakage of household appliances: refers to the connection between the wires of household appliances and the metal shell of household appliances, which is called leakage of household appliances.
The multimeter judges whether the wire is leaking. We also use the buzzer of the multimeter to measure the live wire and the ground wire, and the zero wire and the ground wire with red and black probes respectively. If there is a buzzer, it means that there is leakage. If the multimeter does not respond, it proves that there is no leakage.
The multimeter judges whether the household appliances are leaking electricity. We also use the buzzer of the multimeter, and put red and black probes on the wires of the household appliances and the metal shell of the household appliances respectively. If the multimeter buzzes, it is leaking electricity, and the multimeter does not respond, which proves that there is no leakage.
Remarks: To measure the leakage with multimeter, the power must be cut off first. For the faint leakage of wires or whether the household appliances are leaking, it is generally impossible to measure it with multimeter, so it should be measured with megger.
The methods of measuring short circuit, open circuit and electric leakage by multimeter are basically the same. They all use the buzzer of multimeter to judge whether there is short circuit, open circuit and electric leakage by measuring on and off.
