Project - Analysis of a practical automotive wiring circuit

Q.1) Major elements: Generator, Battery, Voltage and current regulator, Ignition coil, Horns, Sealed light, Fuse, Distributor,Starter, Fuel gauge,etc.

Q.2)

i) Battery: Purpose- Battery is device which is used to store generated electric energy in chemical form. Later when electricity is required it is obtained from battery. All important vehicle devices uses electricity stored in battery.

Working- Battery consist of electodes and electrolytic solution. When electrodes, cathode and annode are inserted in electrolyte solution, the chemical reaction takes place and there is exchange of ions through the electrolytic solution and electrons through the external circuit which is connected between two electrodes. During charging external voltage is applied across the battery terminals and the chemical reaction is reversed.

ii) Generator: Purpose - The generator is the active source of electric energy in car. The electric energy generated by the generator is used to charge the battery continuously in the vehicle and operate the important devices such as head light and ignition system. Because if battery fails we can able to use important devices in vehicle.

working: Generator shaft is connected to engine of the vehicle. When the engine crank rotates the shaft of the generator is also rotated. The shaft of the generator consist of windings and are conected to the external devices. When this shaft is rotated in magnetic field the voltage is generated across the terminals of the generator which is the used for other purposes.

ii) Ignition coil: Purpose- Ignition coil is used to create spark in the engine chamber to ignite the fuel and generate the powerstroke in engine. They produce spark systematically in multi cylinder engine.

Working: Ignition coil is used to produce spark. To produce spark, high voltage is required approx. 30000 volts. To get such high voltage from 12 volt electrical system of the vehicle the ignition coil uses the transformer principal. By means of two coils, one inside the another wounded around the magnetic material the ignition coil transforms the electrical energy from vehicle into high voltage. Then this voltage is used to generate the spark.

Q.3 ) The fuse rating should be slightly higher than load current e.g.

10A is total load from battery then the fuse should be rated to arround 12 Amp or 15 Amp.

Q. 4) If we consider the full charge car battery should last for 1days then,

Battery voltage = 12 volts

Energy used = 500 x 1 x 24/1000 = 12 kWhr

Battery capacity = 12000/12 = 1000 Ahr.

Q. 5) Two Sealed lights and Two horns are elements which are connected in parallel. They are connected in parallel because they require same voltage and more power that can be obtained by parallel arrangment. Generator and battery are connected in parallel.

Q.6) i) Ammeter : It is always connected in series to the battery to measure maximum current flowing through it.

ii) Ignition switch and ignition coil: These two elements are connected in series. Switches are connected in series to the elements to open and close the circuit.