These generators are three-phase alternators.
The formula of the three-phase alternator:
P (power) =√3 x V (line voltage) x I (line current) xcosφ (power factor) Here the power factor is taken 0.8
I (current)=P/(√3xVxcosφ)=20kW/(√3x380Vx0.8)=38A
What size should be of a 380 V, 20 KW motor when the distance is 3 km? How to calculate?
(1) The current of 10 kW of 380 V three-phase electricity is about 20 A. It should be enough to use 4 square MM wires, and the circuit breaker can be slightly larger large, ranging from 25. -32A.
(2) For 380V three-phase electricity of 10kw, it is better to install a 63A circuit breaker with 10 square meters of wire.
(3) 1. 380 V 1 kW = 2 A.
We know that when the coil rotates in the magnetic field, the wire cutting the magnetic field line generates a force induced electromotive, and its changing pattern can be represented by a cosinusoidal urban. If we take three coils and place them at an angle of 120 degrees from each other in space, the three coils will always rotate at the same speed in the magnetic field and three induced emfs of the same frequency will be induced.
Since the three coils are spaced 120 degrees apart, the current generated is also a three-phase sinusoidal change, called three-phase sinusoidal alternating current. Industrial electricity uses three-phase electricity, such as three-phase AC motors.
Detailed information:
Triangular connection: The load wires of the triangular connection are made of three live wires and one a ground wire. The voltage between the three live wires isof 380 V and the voltage between any live wire and the ground wire is 220 V;
< p>Y-shaped connection: The load wires of the Y-shaped connection are three-phase lines, neutral line and ground wire. The voltage between the three-phase lines is 380 V. Any phase line is connected to the three-phase line. neutral line or ground wire. The voltage is 220 V.Three-phase electric meters Three-phase electric meters include mechanical meters, ordinary electronic meters and magnetic card electronic meters. General specifications are: 1.5(6), 5(20), 10(40). , 15(60), 20(80), 30(100) (voltage 3×380/220V~).
Baidu Encyclopedia-380V
The line is too far and n is no longer available. Application value, however, it is possible to use very thick wires regardless of cost. You might as well calculate:
The current of a motor de 20KW: I≈40A, terminal voltage is 380V and terminal voltage can be 360V, phase-to-phase voltage drop is 20V, single line voltage drop: U=10V, distance : L=3KM, resistivity of copper core wire: ρ=0.0172
Find the resistance in a single line:
R=U /I ＝10/40＝ 0.25(Ω)
Find the cross section of the line:
S＝ρ×L/R＝0.0172×3000/0.25≈206(square)
Motor (English: Electric machines, commonly called "motor") refers to an electromagnetic device that converts or transmits electrical energy based on the law of electromagnetic induction. It is represented by the letter M (D in the old standard) in the circuit. Its main function is to generate motor torque and serve as a source of energy for electrical appliances or various machines. The generator is represented by the letter G in the circuit. Its main function is to convert electrical energy thn mechanical energy.