How to measure three-phase electric phase loss with multimeter
Three-phase electrical phase loss means that one or two of the three phase lines have no voltage. When the user uses electricity, if only one phase wire is taken, and it happens that this phase wire is out of phase, then the user end will have a power outage. If it is a three-phase electrical equipment, it can still be used after one phase is missing, but it will cause voltage instability, which is easy to rise or fall suddenly.
Three-phase electrical phase loss, the measurement method with a multimeter
Multimeter to measure phase loss
In three-phase electricity, the voltage of the phase line to the ground and to the neutral line is 220V. Use the voltage file of the multimeter to measure the voltage between the three phase wires and the ground or neutral wire in sequence. Under normal circumstances, it should be about 220V. If the voltage is 0 or too low, it proves that the phase line is out of phase.
The voltage between the phase lines should be about 380V. Measure the voltage between AB, AC, and BC in turn. If the voltage is far less than 380V, it proves that at least one of the two phases measured is out of phase.
For example, if the voltage measured by AB is low, it proves that at least one of the two phases A and B is out of phase. Then measure BC, if the voltage is normal, it proves that phase A is missing.
Precautions for measuring DC current with multimeter
1. Carry out mechanical zero adjustment.
2. Select the appropriate range gear.
3. When using the multimeter current block to measure the current, the multimeter should be connected in series in the test circuit, because only the series connection can make the current flowing through the ammeter the same as the current of the branch circuit under test. When measuring, the branch under test should be disconnected, and the red and black test leads of the multimeter should be connected in series between the two points where the quilt is disconnected. Special attention should be paid to the fact that the current meter can be connected in parallel in the quilt test circuit, which is very dangerous and can easily burn out the multimeter.
4. Pay attention to the polarity of the measured electricity.
5. Correct use of scales and readings.
6. When the 2.5A range of DC current is selected, the red pen of the multimeter should be inserted into the 2.5A measurement jack, and the range switch can be placed on any range of the DC current range.
7. If the DC current measured by the quilt is greater than 2.5A, the 2.5A gear can be expanded to a 5A gear. The method is very simple, the user can connect a 0.24 ohm resistor between the "2.5A" jack and the black test lead jack, so that the gear becomes a 5A current gear. The connected 0.24A resistor should be a wire-wound resistor above 2W. If the power is too small, it will burn out.
