How to measure the line with a multimeter before power is sent
The construction site went online and the lights and panels were installed. How can I use a multimeter to measure whether there is any problem with the line before the power is sent? In order to ensure that the wire panel lights are not burned out during power transmission.
The first step is to confirm whether the rated voltage of the lamp is consistent with the voltage at the power supply point. Use a multimeter to adjust to the AC voltage 500 (600) V gear and measure the voltage at the input terminal (switch) of the power supply point. It can be known that the voltage is 220V or 380V. The rated voltage is 220V, if the voltage is 380V, it will burn the lamp;
The second step is before the power is turned on, use a multimeter to adjust the output terminal of the power supply (switch) to the diode position to measure whether there is a short circuit in the power supply line of the lamp. If there is a short circuit, the resistance value is generally between 0 and several ohms (000-010). At this time, the next step of confirmation and testing is required. If the value is several thousand ohms or infinite, it can be ignored;
The third step is to confirm the power-on voltage of the lamp and the power-on (turn on the switch) under the condition that the line is not short-circuited. If the light controlled by the power-taking place (switch) is not on, it is necessary to check whether the common line at the lamp end is disconnected. Electrically disassemble one of the bandages (common wiring) of the common end, disconnect the line and pay attention not to touch other things, then use a multimeter to adjust the AC voltage to 500 (600) V, and use a black meter to ground. Use the red meter as an electric pen to test and measure both ends of the disconnected line. If the voltage displayed by the multimeter is more than tens of volts, the test shows that the line is not disconnected. If there is no voltage at both ends of the test, you need to cut off the power at the power-taking place (switch) Swap the two wires and connect them before measuring. The line with voltage end is good, and the line with no voltage end is abnormal. The former is suitable for on-off judgment measurement of 380V line, and the latter is suitable for on-off judgment measurement of 220V line; if only some lamps are not on Then re-check the branch line of the lamp, the power output connection and other problems.
