What is the reason why there is voltage when measuring three-phase electricity with an electric pen without electricity using a multimeter
Firstly, let's understand that the three-phase voltage is different from the commonly used single-phase three-phase voltage in our family. The line voltage between phases is 380V, which is commonly used to drive electric motors, three-phase machinery, and equipment. If one phase of the three-phase voltage is missing, it will cause the instrument and equipment to malfunction or even burn out.
So if we feel there is a problem with the three-phase voltage, we should immediately use a multimeter to measure the line voltage. If it is all 380V and there is no short circuit between the line and ground, it can be used normally. It is not recommended to use an electric pen to measure 380V. Firstly, the quality of the electric pen varies, and some electric pens cannot even measure the voltage of 380V.
Some electric pens have a relatively small range, and if they exceed their range, they will not display or display an alarm. We mistakenly believe that this is due to the lack of power or a fault in the phase line, which has a misleading effect. Therefore, we try to use a multimeter when measuring the line voltage.
In addition to having problems with using an electric pen and not being able to measure the voltage, there is also a possibility that this phase is short circuited to ground. If there is a real short circuit to ground, using an electric pen sometimes measures unfamiliar voltage, but using a multimeter to measure the line voltage can display the voltage value. At this time, the displayed voltage value is likely not 380V, but rather 220V.
Of course, there is also a possibility that we mistakenly operated and the measurement points were not accurate. For example, in a three-phase AC contactor, it is very likely that one of the three main contacts in the three-phase AC contactor has a problem, causing the circuit to be disconnected. However, we are measuring the lower end of the AC contactor, so a certain main contact in the lower section must be without electricity.
