The Novice Writer: Generation of Power

Generation of Power

~Jay Mehta

We know that we can use 6 to 24 V direct current battery specifications for our vehicles to work with complete effectiveness.

Two methods which may provide us electrical power: -

Electrochemical –primary batteries (vehicles).
Electromagnetic – power plants (locomotives).

Generators and Alternators: -

Initially, generators took the form of DC dynamo of the appropriate voltage.
Alternating current generator or alternator is the advancement seen automobile engineering.
Even though we have started using alternators in our vehicles we convert the AC into the DC to charge our battery and power some of our electronics.
Generators are machines that use mechanical movement to form electrical energy.

Basic Principles of Electricity and Magnetism: -

Faraday’s Law of Electromagnetism is the basic law of electromagnetic predicting how a magnetic field will interact with an electric circuit to produce an EMF (electromotive force). Used in transformers, inductors, and types of electrical motors, generators, and solenoids.

The induced EMF in any closed loop circuit is equal to the negative of the rate of change of the magnetic flux enclosed by the circuit.

Essential Parts of the Generators: -

Consist of an iron frame, made up of thin sheets of special iron to produce better magnetic conditions, on which the coil is wound to make the frame an electromagnet (stationary part of the electromagnet is called the stator).
The coil that produces the magnetic field is called the field coil.
Within this frame lies the rotating part called as the rotor.
The rotor also has the laminated iron as its core which helps to improve the magnetic field of the coil.
Increasing the number of turns and forming many such similar rotor coils we can drastically increase the magnetic field.
The commutator is the insulated centerpiece of the generator which rotates with the shaft having rotor’s coil connected to the copper segments placed above the insulated centerpiece.
In DC generators it is important to note that it is convenient to rotate the commutator over the magnet because in this way we can get a precision of steps as the change in voltage occurs in the commutator.

The Alternator: -

We make the electromagnets move in this case and keep the conductor stationary.
An electromagnet, in this case, comprises a coil fed with direct current and mounted on shaft together with iron pole pieces to direct the magnetic lines of forces to where they are most effective.
Two copper rings are mounted on the magnetic fixed frame of the insulated shaft. Ends of the rotating magnetic coil are connected to these brushes mounted on the brush holders which are attached to the frame pressing the slip rings and feed the direct current so causing the coil and its pole pieces to become a rotating electromagnet.

Three Phase Winding System: -

An advantage of the three-phase winding system in an automobile is, an output of such a machine is an alternating current at a frequency that depends on the speed at which the rotor is rotated by the engine.
It even makes the circuitry light weight, smaller and yet produces a higher amount of magnetic field.

Converting AC into DC: -

Conversion is done by the process of ‘Rectification’.
It is much easier to do it in a three phase system.
If we clip off the negative part of the waveform then we will be left with only the undulating DC current.
But if we use three phase system we get multiple AC waveforms and clipping off the negative cycle now gives us a more positive result which increases the usability of the energy produced.
Diodes are the basic components in rectifying circuits.
To protect the diodes from overheating we connect heat sinks with each diode which would cool down the diode. They are usually mounted on the alternator in such a way that they are directly cooled by the radiators and fan of the engine.

Diode Connections: -

Six diodes are used to rectify a three-phase network. This connection of diode provides a current path to each three phase signal irrespective of the phase angle or magnitude of the voltage. Hence, helps in an effective use of the input signal and provides it to the output with high efficiency.

Reasons for the use of the Alternators: -

The alternator needs less maintenance than a DC generator.
Slip rings are simple than commutator.
Slip rings don’t wear and tear the carbon brushes more as compared to a DC generator.
DC generator cannot provide enough charging current at low speed to cope up with the continuously increasing demand on the battery.
Alternators can have much smaller rotating elements, providing more energy than a heavy DC generator’s armature.
Needs less maintenance than a DC generator as brushes of DC generator carry current as high as 30A whereas alternators carry only exciting current through them. Hence, Alternators need less maintenance.

~Jay Mehta