By: Kaylie D

#industrialrev      #Kettner   

AC motor

An AC motor is an electric motor driven by an alternating current. it was invented in 1886 by Nikola Tesla.

It is a motor that has a high current in which the high current must flow through the rotating contacts. Heating and sparking at those contacts can waste energy and shorten the lifetime of the motor. In most ac motors the magnetic field is produced by an electromagnet powered by the same ac voltage as the motor coil.

Positives and Negatives of the AC motor

Some Positives of a AC motor is the fixed number of winding sets (known as poles) built into the AC motor, which determines the ac motor's base speed. Also, The frequency of the AC line voltage. Variable speed drives (Adjustable speed drives) change this frequency to change the speed of the motor. And the amount of torque loading on the motor,which causes slip.

Some disadvantages of the AC motor are the speed because it is more hard to control, AC motors can be equipped with variable frequency drives, which provide smooth turning moment, or torque,at low speeds and complete control over the speed of the motor up to its rated value. Also, the control complexity is another disadvantage because the device used to control an AC motor, known as the AC drive, is typically more complex than that used to control a DC motor.

An AC motor controller must convert AC mains electricity to DC, and convert DC back again to an adjustable frequency and voltage output to the AC motor.  

How it works

In an AC motor, there's a ring of electromagnets arranged around the outside (making up the stator), which are designed to produce a rotating magnetic field. Inside the stator, there's a solid metal axle, a loop of wire, a coil, and a squirrel cage made of metal bars and interconnections (like the rotating cages people sometimes get to amuse pet mice), or some other freely rotating metal part that can conduct electricity. Unlike in a DC motor, where you send power to the inner rotor, in a AC motor you send power to the outer coils that make up the stator. the coil are energized in pairs, in sequence, producing a magnetic field that rotates around the outside of the motor.         

Today's version

Your Refrigerator, Washer and Dryer,Oven and lights all use Alternating Current (AC) so that is what today's versions of Alternating Current.   

Essential Question

The impact of the AC motor for both Northern and Southern parts was good because it could be sent long distances over relatively small wires at a convenient high voltage, then reduced in voltage to that used by a customer.