Project - Analysis of a practical automotive wiring circuit

1) Major elements in an automotive wiring diagram

• Generator
• Battery
• Distributor
• Breaker
• Stator
• Earthing (Grounding)
• Ammeter
• Current and voltage regulator
• Switch
• Junction block
• Electrical lamp

2) Three major elements and their working principle

1. Generator

Generators are one of the main components of an electrical system which is used to produce electric energy whenever the system demand for it. The electrical power will generate by means of mechanical action or by any available natural resources as input energy and can be stored in batteries or can be directly supplied to the required output system. Generators are available in different electrical and physical configurations for use in different applications.

Working principle of generator

An electric generator is a device that converts mechanical energy obtained from an external source into electrical energy as the output. it uses the mechanical energy supplied to it to force the movement of electric charges present in the wire of its windings through an external electric circuit. This flow of electric charges constitutes the output electric current supplied by the generator. This mechanism can be understood by considering the generator to be analogous to a water pump, which causes the flow of water but does not actually ‘create’ the water flowing through it.

Electric generators work on the principle of electromagnetic induction. A conductor coil (a copper coil tightly wound onto a metal core) is rotated rapidly between the poles of a horseshoe type magnet. The conductor coil along with its core is known as an armature. The armature is connected to a shaft of a mechanical energy source such as a motor and rotated. The mechanical energy required can be provided by engines operating on fuels such as diesel, petrol, natural gas, etc. or via renewable energy. sources such as a wind turbine, water turbine, solar powered turbine, etc. When the coil rotates, it cuts the magnetic field which lies between the two poles of the magnet. The magnetic field will interfere with the electrons in the conductor to induce a flow of electric current inside it.

The function of the generator also called as alternator in automobiles is to supply current for the operation of the ignition system, the lighting system, and all other electrical parts when the engine is running and to replenish the battery after it has supplied current for starting and other purposes when the engine is at rest.

1. Battery

A battery is a collection of cells that stores chemical energy and converts it into electrical energy. Which supplies electrical energy whenever the system demands it.

Working principle of battery

A battery works on the oxidation and reduction reaction of an electrolyte with metals. When two dissimilar metallic substances, called electrodes, are placed in a diluted electrolyte, oxidation and reduction reactions take place in the electrodes respectively depending upon the electron affinity of the metal of the electrodes. As a result of the oxidation reaction, one electrode gets negatively charged called cathode and due to the reduction reaction, another electrode gets positively charged called anode. This difference in electron concentration causes an electrical potential difference developed between the metals. This electrical potential difference or emf can be utilized as a source of voltage in any electronics or electrical circuit.

1. Distributor

Electrical distribution systems are an essential part of the electrical power system. In order to transfer electrical power from an alternating current (AC) or a direct current (DC) source to the place where it will be used, some type of distribution network must be utilized.

Working principle of battery

Distribution systems usually employ such equipment as transformers, circuit breakers, and protective devices. The distributor’s primary feature is to direct secondary, or excessive voltage, current from the battery to the equipment in the correct order, and for the correct amount of time. The contact factors of the contact breaker open and collapses the primary current through the primary winding. This produces an excessive voltage current in the secondary winding. The excessive voltage current produced is transferred to the distributor’s relevant terminal.

3) Fuse Rating

The function of a fuse is to break a circuit when a current threshold is exceeded. It’s a single-function device, and historically single-use. Calculating the rating of very basic protection equipment fuse, we use the thump rule just select a fuse rated 150% - 200% of the normal operating current of the specific circuit.

Given data

Total Load from battery =10A

Battery voltage =12V

To find

Fuse rating of the system

Solution

The fuse rating can be calculated by dividing the power used by the output system by the voltage going into the system.

I (Amps) = P (Watts) ÷ V (Voltage)

Here the rated current is given in the input data as 10A

It is recommended to keep the fuse rating higher than the maximum load of the equipment. Generally, 1.5 times more than the maximum load of equipment.

Thus the fuse has a rating rages from 12-14A will be good enough for a rated operating load of 10A.

4 )Voltage and capacity of the battery

Given data

Load =500W

To find

To suggest a battery with Suitable voltage and capacity for driving the given load

Solution

Voltage is given as 12V

P=V*I

I=500/12

I=41.66

If 500W is used for 1hr then,

Capacity =I*T

Capacity =41.66*1H

Capacity =41.66AH

It is recommended to use a battery of capacity more than 100AH

5) Two elements connected in parallel to each other in an automotive wiring circuit

The generator and regulators (voltage & current) are connected in parallel in the wiring circuit. By connecting them in parallel we can obtain a constant voltage across their ends which will give accurate regulations throughout the system.

6)Two elements connected in series to each other in an automotive wiring circuit

Battery and stator are connected in series in the wiring circuit. In order to obtain the same current we connected them in series thus it will eases a smooth and quick start of the vehicle.