The current calculation formula of the 380V motor (three-phase air-conditioning compressor) is: I = rated power ÷ (1.732 × rated voltage × power factor × efficiency).
Power factor is an important technical data of power system. Power factor is a coefficient to measure the efficiency of electrical equipment. The low power factor indicates that the reactive power of the circuit for alternating magnetic field conversion is large, which reduces the utilization rate of the equipment and increases the loss of line power supply.
The calculation formula of three-phase electricity (380V) power, voltage and current power = current × (1.732 × 380 voltage × 0.85 power factor × 0.9 efficiency). For example, the calculation method of the rated current of the motor in 7.5 is 7500÷(1.732×380×0.85×0.9)=14.896A.
1. Line Voltage (Line Voltage) is the voltage between the two lines of the multi-phase power supply system, taking three phases as an example, the voltage between the A, B, and C three-phase lead-out lines, also known as the line voltage. The magnitude of the line voltage of the star connection is three times the square root of the phase voltage. The phase voltage of a delta power supply is equal to the line voltage.
2. The voltage between any phase line and neutral line of the three live wires is called phase voltage Ua, Ub, Uc. In my country's low-voltage power supply system, the voltage between each of the three phase lines and the neutral line is 220 volts.
The voltage between the three phase lines is called line voltage. In a symmetrical three-phase system, the magnitude of the line voltage is 1.73 times the phase voltage. In my country's low-voltage power supply system, the line voltage is 380 volts.
Extended information:
1. Line voltage calculation rule
The relationship between the line voltage and the phase voltage of the three-phase power supply is (taking the power supply side as an example):
① For delta connection, the line voltage is equal to the phase voltage.
② For star connection, the relationship between line voltage and phase voltage is UAB=UAN-UBN, UBC=UBN-UCN and UCA=UCN-UAN.
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 is self-evident for delta sources (or delta loads). For star-shaped power supply (or star-shaped load), take the positive sequence symmetrical group as an example, there are:
UAB=UAN-UBN= √3UAN
UBC=UBN-UCN= √3UBN
UCA=UCN-UAN=√3 UCN
Second, the difference between line voltage and phase voltage
For the phase voltage, it is generally understood as the voltage between phases and phases, which is 380v, while the line voltage is understood as 220V.
The 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 to say, the phase voltage should be 220V, while the line voltage is 380V.
There are three live wires (line voltage) coming out of the power plant. After using a transformer to boost the voltage and send it out, the point used is to use a step-down transformer to step down the voltage to 400V (still the voltage of the three live wires).
The neutral wire is drawn from the junction of the three sets of coils of the step-down transformer winding. The transformer is star-shaped, and the four wires here are aligned.
They are respectively connected to users (loads) through the power distribution cabinet. The three live wires are generally named A, B, and C, and the neutral wire is N. Use 380V line voltage to connect A, B, C. Our family uses 220V phase voltage. 400 and 380 vary. Yes, the 20V there is consumed in wiring etc.
Reference source: Baidu Encyclopedia - Line Voltage
Reference source: Baidu Encyclopedia - Phase Voltage
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The line voltage refers to the voltage between the two lines of the multi-phase power supply system. Taking the three-phase as an example, the voltage between the three-phase outgoing lines of A, B, and C is also called the line voltage.
Phase voltage refers to the voltage across each phase of a three-phase power supply or a three-phase load.
The magnitude of the line voltage of the star connection is three times the square root of the phase voltage. The phase voltage of a delta power supply is equal to the line voltage.
For alternating current, the phase voltage is the voltage between any phase line (live line) and the neutral line, which is 220V. Three-phase alternating current has three phase voltages: the voltage and frequency of the three are the same, and the phase difference between them is 120°. The voltage between any two phase lines, called the line voltage, is 380V. Three-phase alternating current has three phase voltages, so there are three line voltages: the voltage and frequency of the three line voltages are the same, and the phase difference between them is 120°.
Extended information:
The difference between line voltage and phase voltage:
1. For the phase voltage, it is generally understood as the voltage between phases and phases, which is 380v, while the line voltage is understood as 220V.
2. The 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 to say, the phase voltage should be 220V, and the line voltage is 380V.
3. There are three live wires (line voltage) coming out of the power plant. After using a transformer to boost the voltage and send it out, the point used is to use a step-down transformer to step down the voltage to 400V (still the voltage of the three live wires).
4. The neutral wire is drawn from the contact point of the three sets of coils of the step-down transformer winding. The transformer is star-shaped, and the four wires here are aligned.
5. Receive users (loads) respectively through the accompanying electrical cabinet. The three live wires are generally named A, B, and C, and the neutral wire is N. Use 380V line voltage to connect A, B, C. Our family uses 220V phase voltage. 400 and 380 vary. Yes, the 20V there is consumed in wiring etc.
6. The so-called line voltage refers to the voltage 380 between line and line, and the phase voltage refers to the voltage 220 between line and zero.