Electrical Machines

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Electrical Machines

Brief introduction of Electrical Machines

In electrical engineering, the electric machine is a general term for machines that use electromagnetic force, such as motors and generators. They are electromechanical energy converters: electric motors convert electrical energy into mechanical energy, and generators convert mechanical energy into electrical energy. The moving parts of the machine can be rotating (rotating machine) or linear (linear machine). In addition to motors and generators, the third category that is usually included is transformers. Although they have no moving parts, they are also power converters that can change the voltage level of alternating current.

Electric motors in the form of generators can generate almost all the electrical energy on the earth, while motors in the form of electric motors consume approximately 60% of the electrical energy produced. The development of electric motors began in the mid-19th century and since then it has been a ubiquitous part of the infrastructure. Developing more efficient motor technology is essential to any global energy saving, green energy, or alternative energy strategy.

What Is An Electrical Machine?

A mechanical machine is a device that transforms mechanical energy to electrical energy or vice versa. Transformers are another type of electrical machine that does not really convert mechanical to electrical form, but rather converts AC current from one voltage level to another voltage level.

Types of Electrical Machines

The electric machines are of three main types, transformer, generator, and motor.

Electrical Transformer: In the transformer, both input and output are electrical power.

Electrical Generator: In a generator, the input is mechanical power and the output is electrical power.

Electrical Motor: In a motor, the input is electrical power and output is mechanical power.

Electrical Machines can also be categorized as static machines and dynamic machines.

The transformer is an example of a static electrical machine.

Motor and generator both are dynamic electrical machines.

Transformer: The working principle of the transformer is mutual inductance. The windings of the transformer are connected by iron cores. The magnetic flux in the magnetic core connects the main winding and the auxiliary winding, thereby inducing a voltage in the winding. The operation of the transformer can be summarized as follows.

When an AC voltage is supplied to the main winding, the magnetizing current flows through it, generating and concentrating magnetic flux in the path of the closed low-resistance magnetic core. This magnetic flux is connected to the primary and secondary windings. In the main winding, the voltage is automatically generated, while in the secondary winding, the voltage is mutually induced. Induce

There are two types of transformers based on voltage level: step-up transformers and step-down transformers. Step-up transformers are used to increase the voltage of electricity. Step-down transformers are used to reduce the voltage of electricity.

Transformers are classified into three types based on their applications: power transformers, distribution transformers, and instrument transformers.

The transformer is classified as two winding transformers or autotransformers based on the design requirements.

Transformers are classified into two types based on their insulation system: oil-immersed transformers and dry-type transformers.

A transformer can be either a single-phase or a three-phase transformer, depending on the working phase.

A three-phase transformer can alternatively be a single-unit transformer or a multi-unit transformer.

Emf is induced in a conductor when it is moved in a magnetic field. This is the dynamically induced emf principle. All electrical generators operate on this basis.

There are two types of generators – DC generator, AC generator, or alternator.

DC Generator: The rotor in a DC generator is an armature (assembly of wires), and the electromagnetic poles are attached to the stator. When the rotor spins in the stator, an alternating current is induced in the armature and collected through commutator segments linked to the motor’s shaft. The commutator converts the alternating current generated in the armature to a direct current.

AC Generator: The armature of an alternator is connected to the inner perimeter of the stator. In the stator, the electromagnet spins. The static armature’s electricity is immediately supplied into the external circuit. The rotor electromagnet receives power from the DC supply through a slip ring.

The electric motors can be categorized as DC motors or AC motors.

DC Motors: These motors are powered by a DC power source through a commutator piece connected to the motor shaft. The motor rotates according to Fleming’s left-hand rule. DC motors can be divided into separately excited DC motors, parallel-wound DC motors, series-wound DC motors, and compound-wound DC motors.

There are two types of AC motor. Induction Motor and synchronous motor.

Induction Motors: Single-phase induction motors and three-phase induction motors are the two types of induction motors. A squirrel-cage rotor or a wound-type rotor can be used in an induction motor. When an induction motor is powered by electricity, a spinning magnetic field is created. The spinning magnetic field interacts with the rotor conductors, causing current to be induced in the conductors. The induced current flows through the rotor conductors as a result of the relative motion of the rotor and stator. The rotor attempts to capture the rotation of the magnetic field to minimize the source of induced current. As a result, the rotor begins to revolve.

Synchronous Motor: A revolving magnetic field is created in the stator of a synchronous motor. The motor’s rotor is an electromagnet that is magnetically locked with the spinning magnetic field, causing the rotor to rotate.

Other forms of electric motors include servo motors, stepper motors, hysteresis motors, and so on.

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