Why does a multimeter show resistance when measuring a short circuit in a circuit?
Before the circuit is powered on for the first time, I will use a multimeter to check whether there is a short circuit in the circuit. Everything is normal at this time. The multimeter does not beep and displays infinity.
After using it for several months, during routine maintenance, I used the multimeter to check the short circuit condition. When I put the test leads on the two wires, there was a beeping sound, and then there was no sound. The multimeter screen showed 60 to Resistance value of more than 80.
So I can't figure out whether it's a short circuit or not, and the gate can be closed, so it feels baffling.
1. There was no resistance in the two wires at the beginning. When I checked again after using it for a period of time, I found that the fire and neutral wires actually had resistance when the fire and neutral wires were turned off, and the buzzer still sounded. In daily practice, I saw this situation, and my judgment is as follows:
2. The known condition is that after indoor installation and debugging, there is no resistance between the lines when there is no load. How come after the user has used it for a period of time, there is resistance between the lines when there is no load? Is this a leaky wire? This phenomenon is the most sensitive issue for the official electrician in the country. His first reaction is to use a megger. Without a megger, the problem cannot be found. This phenomenon is similar to that between old and young doctors. The old doctor knows the disease as soon as he hears the chief complaint, while the young doctor relies on instruments.
3. I often use the 400V stepless capacitors on energy-saving lamps as resistors, and remove the neon tube starters from old fluorescent lamps and connect them in series to serve as indicator lights, because this type of indicator light has been seen in mobile sockets. Electrodeless capacitors have a characteristic that they can store a certain amount of charge. If you pass electricity, you will feel an electric induction on someone's hand if you accidentally touch it.
4. When rechecking the resistance value, it only reflects twice, and then it disappears. This is the example I gave above.
5. When the user has a mobile socket on the wall socket, there is a switch and indicator light on the mobile socket. After turning off the main power, the mobile socket is not unplugged (my experience summary, all articles about electricity Prompt to remove all plugs and indicator lights) It is the fire and neutral wires caused by the indicator light that are connected.
