What is the phase voltage? What is the line voltage? There are differences and differences between them. This article will be interpreted one by one.
The delta connection and the star connection that does not lead to the neutral point have three end lines of three-phase three-phase system, three live lines, 380V, and line voltage. The star connection that leads to the neutral line counts three fire lines. There are four power lines, three-phase four-wire system, one fire and one zero, and 220V phase voltage. The line voltage is the vector sum of the phase voltages of the two phases. Line voltage = 2 * phase voltage * cos 30 degrees = root number 3 * phase voltage 380 = root number 3 * 220
Many times, for the phase voltage, it is generally understood that the voltage between the phase and the phase is 380V, and the line voltage is understood as 220V, which is exactly the opposite.
The phase voltage is also the 220V household voltage we often say. The voltage between the neutral line and the live line becomes the phase voltage. In fact, all the voltages in our home are phase voltage.
The line voltage is directly pointing to the voltage of any two live lines, which is what we often say 380V, which is actually the phase voltage. The phase voltage is 220V and the line voltage is 380V.
Relationship difference:In the long-distance transmission process, the higher the voltage, the lower the loss, which is why the country has been studying the ultra-high voltage transmission (I=U/R). Generally, the high-voltage transmission power is sent to the terminal user terminal, and then the transformer is reduced to the commercial power 220V/380V to supply different users.
In a three-phase four-wire system, the voltage between any of the three phase lines and the neutral line becomes the phase voltage; the voltage between any two of the three phase lines becomes the line voltage. The phase of the three-phase voltage differs by 120 degrees. The line voltage is the vector sum of the phase voltages of the two phases. The relationship between the line voltage and the phase voltage is: line voltage = phase voltage of 3 times the root number, ie 380V = 3 times the root number 220V (sorry, the headline can't upload the mathematical root number of the formula 3).
The two-phase electrical connection is on the running three-phase motor, and the motor can still work. This is what we often call the motor phase loss operation, but this way it is easy to burn the motor. After the phase connection of the three-phase motor connected by the delta connection, the output power of the motor will also become two-thirds of that of the original three-phase electric power supply, and the other two windings only provide one-third of the power, thus causing three-phase Unbalanced, unbalanced current, unbalanced current, the motor is of course more susceptible to burnout.
After the star-connected three-phase motor is out of phase, the motor output power is completely provided by two windings, the load is increased by 50%, and the other winding does not work, so the operating current is unbalanced and the motor is easily burned out. When the two-phase motor is stopped on the stopped three-phase motor, the motor cannot be started. For a single-phase motor, after the two phase lines of 380V are connected, the voltage becomes 380V, which is 220V, so that the voltage rises and the motor is definitely burnt out.
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