What Is Single-Phase Electric Power?
Voltage across each phase of a three-phase power supply or three-phase load. In the star connection (the neutral point is set to N) is the relative neutral point voltage, the phase voltages of phase A, B and C are U AN , U BN , U CN; The phase-to-phase voltages are the phase voltages of phase A, phase B, and phase C, respectively, U AB , U BC, and U CA.
- The voltage between any of the three live wires and the neutral is called the phase voltage Ua, Ub, Uc. In China's low-voltage power supply system, the voltage between each of the three phase wires and the neutral is 220 volts.
- The voltage between the three phase wires is called
- The three-phase voltage star connection method is to connect each phase power supply or
- The relationship between the line voltage and phase voltage of a three-phase power supply is (take the power supply side as an example):
- (1) For delta wiring, the line voltage is equal to the corresponding phase voltage;
- (2) For star wiring, the relationship between line voltage and phase voltage is U AB = U AN -U BN , U BC = U BN -U CN and U CA = U CN -U AN
- If the phase voltage of the three-phase power supply is a positive-sequence (negative-sequence) symmetrical group, the three-phase line voltage is also a positive-sequence (negative-sequence) symmetrical group. This pair of triangular power supplies (or triangular loads) is self-evident. For a star power supply (or star load), taking a positive sequence symmetrical group as an example, there are:
- U AB = U AN -U BN =
- U BC = U BN -U CN =
- U CA = U CN -U AN =
- It can be seen that in a symmetrical three-phase circuit, regardless of the three-phase power supply or three-phase load, U l = Up when the delta connection is used and U l = when the star connection is used
- For phase voltage, it is generally understood as the voltage between phases is 380v, and the line voltage is understood as 220V.
- Phase voltage refers to the voltage between the phase line, that is, the live line and the neutral line, and the line voltage is the voltage of any two live lines on the line, that is, the phase voltage should be 220V, and the line voltage is 380V.
- There are three live wires (line voltage) coming out of the power plant. When using a transformer to boost the output, the point used is to step down to 400V with a step-down transformer (still the voltage of the three live wires).
- The neutral wire is drawn from the contacts of the three sets of coils of the step-down transformer winding. The transformer is star-shaped, and the four wires here are all aligned.
- Connected to users (loads) through distribution cabinets. The three live wires are generally named A, B, and C, and the neutral wire is N. A line voltage of 380V is connected to A, B, and C. Our family is using 220V phase voltage. 400 and 380 range. Yes, the 20V voltage there is consumed in the line and other equipment.
- The so-called line voltage refers to the line-to-line voltage 380, and the phase voltage is the line-to-zero voltage 220. [2]