Question

Difference between linear induction motor and three phase squirrel cage induction

Answer 1

Three phase induction motors have three phases, so the first requirement is a three phase supply. The three phases are 120 degrees apart, so that a proper rotating field is produced. They tend to be smaller and cheaper and run smoother than an equivalent single phase motor. They can be more efficient than some single phase motors. As some of these can be large, they can need a specific starting arrangement to reduce the sudden surge at start-up, and perhaps to control the acceleration. Sometimes a star delta starter is used, and these need a supply with neutral. There would be 6 wires brought out from the windings for this purpose, one pair for each phase. Some even have 12 wires, so they can accommodate a range of voltages as well. Three phase motors can be reversed by reversing the connections to any one phase. This means that the direction of rotation should always be checked after installation.

   A DC motor is any of a class of electrical machines that converts direct current electrical power into mechanical power. The most common types rely on the forces produced by magnetic fields. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current flow in part of the motor. Most types produce rotary motion; a linear motor directly produces force and motion in a straight line.