Electrical 2: Motors: Theory and Application

Describe how DC motors operate. Identify the component parts of series shunt and compound DC motors. Identify typical applications of DC series shunt and compound motors. Describe the basic construction and components of a three-phase squirrel cage induction motor. Explain the relationship between speed and frequency in an induction motor. Describe how torque is developed in an induction motor. Explain how and why torque varies with rotor reactance and slip. Define the following terms: percent slip and speed regulation. Explain how the direction of a three-phase induction motor is reversed. Describe the component parts and operating characteristics of a three-phase wound rotor induction motor. Describe the component parts and operating characteristics of a three-phase synchronous motor. Describe the operation of a variety of single-phase AC motors. Identify the component parts of single-phase AC motors. Recognize and interpret wiring diagrams for single-phase AC motors. Identify specific applications where single-phase motors may be used. Explain the relationship between speed and the number of poles in an induction motor. Describe the operation of multiple-winding AC motors. Describe the operation of consequent-pole AC motors. Describe the operation of a variable speed AC drive. Identify common types of open motors. Identify common types of totally enclosed motors. Describe types of motor enclosures using a National Electrical Manufacturers Association (NEMA) table. Identify the frame designation number on a machine nameplate. Interpret the D and 2F dimensions on the nameplate of a medium machine. Read dimension sheets for foot-mounted machines. Interpret the information on a motor nameplate. Consult a nameplate when replacing or installing a motor. Match a motor to an application by reading the nameplate. Select fuses for motor control applications. Determine how many overloads should be used in a motor control circuit.