AC machines work by alternating current. Their energy is transferred to the other part of the machine. One of these machines, called the stator, contains an electromagnetic circuit. It is composed of thin metal sheets stacked on top of one another to create a hollow cylinder. This construction minimizes energy loss. AC machines are commonly used in industrial applications. For more information about AC machines, read on. This article provides an overview of the different types of AC machines.
Split-phase induction motors
A Split-phase induction motor can operate at 115/230V and is capable of delivering a maximum starting torque of 3450 rpm. It has 2 poles and a starting winding with a high resistance. If the starting time exceeds five seconds, the motor can become inoperable. Its power rating varies from 60 W to 250 W. The following are a few examples of applications that can benefit from these motors.
A typical design features a starting winding that is connected in parallel to the main winding. Once the motor is running at a constant speed, the starting winding is automatically disconnected from the mains supply. This disconnecting process is normally carried out by a centrifugal switch or a relay. The starting winding is connected in parallel with the main winding at start up and is disconnected from the mains supply once it reaches 70 to 80 percent of synchronous speed.
Synchronous AC motors
Synchronous AC motors use two separate electrical inputs, one for the rotor and the other for the stator. These are called doubly-excited motors because their magnetic poles are excited by two separate sources. The three-phase AC supply is used to energize the stator, while the DC supply starts and excites the rotor. Synchronous AC motors are often used in manufacturing facilities, power stations, and voltage control in transmission lines.
In contrast, synchronous AC motors use multiple-pole stators, which increase their efficiency and torque. The rotor is wound with multiple pole pieces called coils, and the rotor rotates at different rates depending on the load torque. The higher the torque of a load, the longer the rotor field lags the stator. The maximum torque is achieved when the rotor field lags the stator by 90 degrees. If you apply more torque to the motor, however, it will stall.
Induction motors
Induction motors work on the principle of induction, where a magnetic field induces an electric current inside a rotor. The rotor can be a ring, wire, or solid piece of metal. Changing magnetic fields induce a small voltage in the windings, which causes the current to flow through them and create an opposing magnetic field. Induction motors are the most commonly used form of AC machines.
Induction motors produce a net torque when a current is passed through them. The rotor is connected to a power source, and the stator changes its properties into an electromagnet. The rotor is made of steel and stacked with copper or aluminum conductor bars. A steel shaft is pressed into the center of the assembly. This combination of parts generates a magnetic field, resulting in rotation.
Slip ring AC motors
Slip ring AC motors are a versatile and durable way to power AC machines. The basic components of a slip ring are a rotating ring and stationary brushes. The number of brushes and rings depends on the application, and the design may include multiple brushes or stationary ones. The brushes are made of graphite or phosphor bronze. Phosphor bronze has better conductivity and wear resistance. They can either be fixed or rotating, and are secured with end caps and a bearing.
Slip rings are commonly used in electric motors. These slip rings are not available in standard models. Because of this, buyers need to provide specific specifications for their application to get a customized slip ring. When selecting a slip ring, keep in mind the purpose of your motor. If it is intended to transmit power or data signals, it needs to have better EMI mitigation. If it's only needed for starting, a lower-resistance motor will be enough.