理论分析表明，旋转磁场， 如果定子绕组是一个对称的三相对称三相电压施加

Theoretical analysis shows that a rotating magnetic field, if the stator winding is a symmetrical three-phase symmetrical three-phase voltage is applied, there is a symmetrical three-phase current, and a rotating magnetic field in the air gap, the magnetic field rotational speed n1 of the motor is formed is called the synchronous speed, the magnetic poles motor and its relationship to the grid frequency f1 is: n1 = 60 f1 / p phase sequences and three-phase windings and three-phase current steering arrangement of FIG relevant U, V, W-phase are arranged in the clockwise direction, when the three-phase current Walter stator windings U, V, W phase sequence when a stator, a rotating magnetic field rotates clockwise. Since the rotor is stationary, the rotating magnetic field between the rotor and the relative motion, since the rotor conductor cuts the magnetic field generating induction power of the stator, the rotor windings due to its closed, current will flow in the rotor winding. Active rotor current and rotor phase induced electromotive force, which direction may be "right generator" normal. Current active stator member carries a rotating magnetic field of the rotor winding, the electromagnetic force F., To determine the direction from "left motive gives" a. An electromagnetic force forming a magnetic torque shaft, which is consistent with the action of the rotating field direction of the direction of rotation direction of the rotating magnetic field of the rotor, the power input into rotational mechanical energy. If the motor shaft has a mechanical load, a mechanical load with the rotation of the motor, the mechanical motor load is completed. The foregoing analysis shows that the basic principle of rotation of the three-phase asynchronous motors are: (1) three-phase symmetrical three phase winding currents Walter circular rotating magnetic field. (2) cutting the conductor rotor and the rotating magnetic field EMF currents; (3) a carrier as a conductor rotor by electromagnetic forces in a magnetic field, thereby forming a rotation electromagnetic torque, the motor drives the rotor. For the same time there are some electrical classification, it can be divided by function for turning and breaking electrical circuit, electrical circuitry for controlling, for electrical cutoff circuit for detecting electrical circuit coefficient for protecting the circuit appliances. There are low-voltage electrical appliances, low-voltage distribution can be summarized as electrical and low-voltage electrical control two categories. Since these two types of Status and Role in the low-voltage electrical circuit which is also different from a greater difference of their performance requirements.

Theoretical analysis shows that the rotating magnetic field, if the stator winding is a symmetrical three-phase voltage application, there is a symmetrical three-phase current, and the formation of a magnetic field rotating in the air gap of the motor, the speed of the magnetic field n1 is called synchronous velocity, the magnetic pole frequency f1 motor and its relationship to the mesh is: n1 The 60 f1 / p phase sequence and the three-phase winding and steering arrangement three-phase current-related diagrams U, V, and W are arranged in a clockwise direction, when the three-phase current stator winding Walter U, V, And W phase sequence stator, the rotating magnetic field rotates clockwise. Because the rotor is stationary, there is relative motion between the rotor and the rotating magnetic field, and because the rotor conductor cuts the magnetic field to produce the inductive power of the stator, the rotor winding has the current flow within the rotor winding because it is closed. Active rotor current and rotor phase induceelectric force, the direction of which can be "right generator set" normal. The current of the rotating magnetic field in the stator carries the active part of the rotor winding, the electromagnetic force F, from the direction given by the "left motive" is determined. An electromagnetic force forms a magnetic torque axis that acts in the same direction as the rotation field, rotates along the rotational direction of the rotor's rotating magnetic field, and converts the input electrical energy into rotating mechanical energy. If the motor shaft has a mechanical load, the mechanical load rotates with the rotation of the motor and the mechanical work of the motor load is completed. In summary analysis, it can be seen that the basic working principle of three-phase asynchronous motor rotation is: (1) three relative lying windings in the general human three relative called current to produce a circular rotating magnetic field. (2) The rotor conductor cuts the rotating magnetic field to sense the electric potential and current, and (3) the rotor carrier conductor is affected by electromagnetic force in the magnetic field, thus forming an electromagnetic rotation, which drives the motor rotor to rotate. At the same time for electrical appliances also have some classification, can be divided by function for turning on and dividing the electrical circuit, for the control of electrical circuits, for cutting off the circuit of electrical appliances, for detecting circuit coefficients of electrical appliances, for the protection of electrical appliances of the circuit. There are low-voltage electrical appliances, can be summed up as low-voltage power distribution appliances and low-voltage control electrical appliances two categories. Because these two types of low-voltage electrical appliances in the circuit in different positionand and role of their performance requirements are also quite different.

Theoretical analysis shows that the rotating magnetic field, if the stator winding is a symmetrical three-phase symmetrical three-phase voltage applied, has a symmetrical three-phase current, and forms a magnetic field rotating in the air gap of the motor, the rotating speed of the magnetic field N1 is called the synchronous speed, the motor of the magnetic pole frequency f1 and its relationship with the grid are: N1 = 60 F1 / P phase sequence and the three-phase current correlation diagram U of the three-phase winding and the steering layout 5. W-phase is arranged in a clockwise direction. When the three-phase current stator winding Walter u, V, w-phase sequence stator, the rotating magnetic field rotates clockwise. Because the rotor is stationary, there is relative movement between the rotor and the rotating magnetic field. Because the rotor conductor cuts the magnetic field, the induced force of the stator is generated. Because the rotor winding is closed, there will be current flow in the rotor winding. Active rotor current and rotor phase induced electric force, whose direction can be "right generator set" normal. The current of the rotating magnetic field in the stator carries the active part of the rotor winding, and the electromagnetic force F is determined from the direction given by the "left motor". An electromagnetic force forms a magnetic torque shaft, which acts in the same direction as the rotating field, rotates along the rotating direction of the rotating magnetic field of the rotor, and converts the input electric energy into the rotating mechanical energy. If the motor shaft has a mechanical load, the mechanical load rotates with the rotation of the motor, and the mechanical work of the motor load is completed. To sum up, the basic working principle of three-phase asynchronous motor rotation is: (1) three-phase symmetrical current through three-phase symmetrical winding produces circular rotating magnetic field. (2) The rotor conductor cuts the rotating magnetic field to induce the electromotive force and current; (3) the rotor current carrying conductor is affected by the electromagnetic force in the magnetic field, so as to form the electromagnetic torque and drive the motor rotor to rotate. At the same time, there are also some classifications for electrical appliances, which can be divided into electrical appliances for connecting and breaking circuits, electrical appliances for controlling circuits, electrical appliances for cutting circuits, electrical appliances for detecting circuit coefficients and electrical appliances for protecting circuits. There are also low-voltage electrical appliances, which can be classified into low-voltage distribution appliances and low-voltage control appliances. Due to the different position and function of these two kinds of low-voltage apparatus in the circuit, their performance requirements are also quite different.<br>