Analyze the relationship between current and rotor weight

The stator and rotor of YS-H series marine three-phase asynchronous motors are supported by bearings to ensure that they have a relatively reasonable positional relationship in both static and operational states. When starting the YS-H series marine three-phase asynchronous motor, it is necessary to overcome the inertia of the rotor and the friction of the bearings in the bearing system. Therefore, the relationship between the magnitude of stator current can be qualitatively determined from the operation of the bearing system and the process of rotor start-up and operation.

From the analysis of the bearing system of the YS-H series marine three-phase asynchronous motor, the weight of the rotor of the YS-H series marine three-phase asynchronous motor multiplied by the rolling friction coefficient of the bearing is equal to the rolling friction force that the electromagnetic torque needs to overcome when the YS-H series marine three-phase asynchronous motor is running; Therefore, the heavier the rotor of the YS-H series marine three-phase asynchronous motor, the greater the frictional resistance of the rotor weight multiplied by the rolling friction coefficient, and the greater the electromagnetic torque required to maintain no-load rotation. Electromagnetic torque is generated by electric current. The greater the electromagnetic torque, the greater the current that the power supply needs to provide. Therefore, the heavier the rotor, the greater the current required to maintain no-load operation. For large-sized motors, due to the large weight of the rotor, it is necessary to regularly rotate the rotor when the YS-H series marine three-phase asynchronous motor stops running, that is, to adjust the relative position between the rotor and the bearing rolling elements through rotation, in order to prevent deformation of the rolling elements due to long-term compression; Naturally, larger rotor weights require greater force to alter their operating state.

From the analysis of the starting process of YS-H series marine three-phase asynchronous motors, the basic condition for the operation of YS-H series marine three-phase asynchronous motors is that the electromagnetic torque is not less than the resistance torque, and the resistance torque of YS-H series marine three-phase asynchronous motors is positively correlated with the weight of the rotor. The heavier the rotor, the greater its inertia. YS-H series marine three-phase asynchronous motors need to generate a large electromagnetic torque in order to achieve the state change from static to rated speed, especially for power frequency motors. When starting directly at rated voltage, the starting current of YS-H series marine three-phase asynchronous motors can reach 5-7 times the rated current, which is unfavorable for both YS-H series marine three-phase asynchronous motors and the power grid. Therefore, it is necessary to start the YS-H series marine three-phase asynchronous motor through soft start.

The weight of the rotor is not only reflected in the size of the YS-H series marine three-phase asynchronous motor specifications, but also in the different number of poles of the YS-H series marine three-phase asynchronous motor. For YS-H series marine three-phase asynchronous motors with the same power and center height, multipole motors have larger rotor diameters, greater torque, and greater rotor weight. Therefore, under certain conditions, the weight of the rotor is positively correlated with certain performance parameters of YS-H series marine three-phase asynchronous motors.