电机与拖动复习（Motor and drag review）.docVIP

电机与拖动复习（Motor and drag review） Practice 1. A shunt-wound dc motor, if the power supply voltage and exciting current f unchanged, when combined with a constant torque load, found the armature current exceeds rating, someone try after resistance to limit the current in the armature loop, this method. The input power P of the motor, the armature current a, the speed n will be, and the motors efficiency eta will be. 2. The rated voltage of a single-phase transformer is 380V / 220V and the rated frequency is 50HZ, and if the low voltage is mistakenly received 380V i. i. On the top, at this point Φ m , I0 , Zm , P Fe It is. (increase, decrease or change), it can be broken down into size and turn 3. The fundamental wave of single-phase winding is the direction of rotation speed Two rotating magnetic potentials. ,,, 4. When the three-phase induction motor runs in no-load time, the internal loss of the motor includes and P, the motor no load input power 0 is in balance with these losses. Xm It is. , starting 5. Increased core saturation, and induction motors excitation reactance 6. When the rotor of the linear induction motor is connected to the appropriate resistance, the starting current is made Moment. 7. Increase the torque method of winding asynchronous motor. 8. The rated voltage of the vice side of the transformer. 9. If the operating time of induction motor is s, the ratio between electromagnetic power, mechanical power and rotor copper consumption is Pe: P? : p Cu 2 = It is. 10. The power grid frequency of a three-phase eight-pole induction motor is 50 Hz, and the running time of the no-load operation is 735 RPM, which is the frequency of the rotor potential. When the slip rate is 0.04, the rotor speed is, and the electric potential frequency of the rotor is. 11. If the leakage resistance of induction motor increases, the torque of the induction motor will be torque, and its maximum torque. The difference between the electromagnetic power and the input power, includ