Multimeter measurement of three-phase power missing phase method
Phase loss in three-phase electricity means that out of the three phase wires, one or two of the phase wires do not have voltage. When the user is using electricity, if only one phase wire is taken and it happens to be the one that is missing a phase, then the user's end will be out of power. If it is a three-phase electrical equipment, it can still continue to use after missing a phase, but it will cause voltage instability, easy to suddenly rise or fall.
Three-phase power missing phase, using a multimeter measurement method
Multimeter measurement of missing phase
In three-phase electricity, the voltage of the phase line to the ground and to the zero line is 220 V. Use the voltage gear of the multimeter to measure the voltage between the three phase lines and the ground or zero line in turn. 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 wires should be about 380V, measure the voltage between AB,AC,BC in turn, the voltage is much smaller than 380V, it proves that the phase wire is out of phase.
than 380V, it proves that at least one of the two measured phases is out of phase.
Such as, AB measured voltage is lower, it proves that A, B two-phase at least one phase is out of phase. Then measure BC, if the voltage is normal, it proves that phase A is out of phase.
Multimeter how to measure single-phase pump motor good or bad
To first understand the single-phase motor, single-phase motor is composed of the main winding and sub-winding, with a multimeter measurement, the first multimeter range switch to the ohm file.
Can first measure the main winding ∪ 1 and ∪ 2 resistance, and then measure the secondary winding Z1 and Z2 resistance, in general, the resistance of the main winding to be less than or equal to the resistance of the negative winding, if the measurement of the resistance value of the normal case, the junction box can be removed from the joint piece, in the measurement of the main winding and the secondary winding, between the insulation resistance, in the measurement of the main, the secondary winding of the insulation resistance of the motor casing, if you find that the resistance value of abnormal, zero or no resistance value If it is found that the resistance value is abnormal, zero or no resistance value, or only a few k, it can be basically concluded that the motor may have been burnt bad.
If the insulation resistance value is small, it may be caused by moisture, or short circuit.
Can also open the casing, visual inspection, judgement, if you open the motor, smell a burnt taste, the motor may be burnt.
Can first measure the main winding ∪ 1 and ∪ 2 resistance, and then measure the secondary winding Z1 and Z2 resistance, in general, the resistance of the main winding to be less than or equal to the resistance of the negative winding, if the measurement of the resistance value of the normal case, the junction box can be removed from the joint piece, in the measurement of the main winding and the secondary winding, between the insulation resistance, in the measurement of the main, the secondary winding of the insulation resistance of the motor casing, if you find that the resistance value of abnormal, zero or no resistance value If it is found that the resistance value is abnormal, zero or no resistance value, or only a few k, it can be basically concluded that the motor may have been burnt bad.
If the insulation resistance value is small, it may be caused by moisture, or short circuit.
Can also open the casing, visual inspection, judgement, if you open the motor, smell a burnt taste, the motor may be burnt.
