Multimeter shows short circuit resistance, what is it?
Before the circuit is first powered up, I use a multimeter in the on/off position to measure the line for any shorts before closing the circuit. This time are normal, the multimeter does not beep, also shows infinity.
After a few months of use, routine maintenance, with the multimeter through the short-circuit measurement, the pen on the two lines that will beep for a moment, and then there is no sound, the multimeter screen shows more than 60 to 80 resistance.
So can not figure out whether this is a short circuit or not, and the gate can be closed, it feels inexplicable.
1, at the beginning of the two lines have no resistance, when used for a period of time and then come back to review, turn off the fire zero line actually have resistance, and the buzzer horn is also called, in the usual practice, I see this situation, the judgement is as follows:
2, the known conditions are indoor installation and commissioning after handing over the use of households between the line of no-load resistance, how the user used for a period of time after the line with the line of no-load resistance? Is this a wire leakage? This phenomenon is the country's official electrician is the most sensitive issue, his first reaction is to use the shaking table, no megohmmeter can not find out the problem. This phenomenon is also like the old doctor and young doctors, old doctors listen to the complaints will know what disease, young doctors is to rely on the instrument.
3, I often use energy-saving lamps on the 400V electrodeless capacitor as a resistor, the old fluorescent lamps on the neon tube to take down the glow by a series when the indicator, because this form of indicator in the mobile socket have seen. An electrodeless capacitor has a characteristic, can store a certain charge, if you pass the electricity, do not pay attention to a touch on the human hand with electric induction.
4, double-check the amount of resistance, only two reflections, and then there is no more, that is, I cited this example above.
5, when the user's wall socket has a mobile socket, this mobile socket has a switch and indicator, after closing the main power supply, this mobile socket is not unplugged, (my experience, the article about electricity are prompted to dial all plugs and indicators) is that this indicator is caused by the fire and zero wire is connected.
I do not know what that line is what specification model, length, erection environment, the new line no sound no resistance indicates that it is very normal, with the wire energised as a result of the inter-wire electricity is easy to digital multimeter interference, it is recommended that the wire being tested for shorting treatment and then measured, or with a rocking meter to test the more realistic.
If you really want to measure the resistance value, you need to use a shaking table or insulation resistance table, and then you need to adjust to the resistance gear, what is the matter with the resistance value of the on-off gear?
Still want to measure the resistance value, generally want to disconnect the power, and then remove the load, otherwise it is not meaningful to measure directly.
For example, if it happens to be connected between the zero wire and fire wire is only an incandescent lamp, then measured out is the resistance of the incandescent lamp filament, if it is a fluorescent lamp, then measured out is the equivalent resistance of the fluorescent lamp internal circuit of all the resistance.
