Project - Analysis of a practical automotive wiring circuit

1. The major elements in automotive wiring diagram are - generator , current & voltage regul;ator , battery , ammeter , fuse , starter , ignition coil , breaker , distributor , ignition switch , light , horn

2. GENERATOR :

Purpose : A motor generator is essential for hybrid vehicles and generating electricity . It serves as the main power source when starting and driving a vehicle and assists the engine during acceleration . The regenerative energy generated when applying the brakes is used to charge the battery . It plays a key role in improving the dynamics performance and fuel efficiency of hybrid vehicles . The function of the generator 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

Working : A car generator is a dynamo it is able to produce electricity through the rotation of tightly wound fine wires in a magnetic field . This magnetic field is maintained by a fixed arrangement of magnets or electromagnets surrounding the spinning windings of wire . The current and voltage produced depends on the speed at which the wires spin and the strength of the magnetic field .

The alternator is an improvement over the car generator . Morden automobile models no longer actully use generators . The structure is reversed in alternator . Instead of spinning wound wires within a fixed magnetic field , the magnet are spun within the winding . This design no longer needs a commutator but rather uses diodes . These are solid-state devices that allow electricity to move in only one direction , successfully achieving the conversion of alternating current to direct current . Alternators are more efficient because they can output more power even when the car is idling , a function that a car generator is not capable of performing .

BATTERY :

Purpose : The first purpose of an auto battery is to provide power for starting your vehicle . It also acts as a surge protector for the car's computer and provides power for short-term use of things like light , stereo , Gps or wipers when the engine is off . The car battery is a part of starting system . The main component in this system the ignition switch and the switch controls.

The ignition switch is either the starter button you press or where you insert your key . The switch controls the starter relay ( also called solenoid ) when you turn the ignition it send a small electrical current to the starter relay . This cause a pair of contacts to close when those contacts close , the battery send voltage to the starter motor , which turn some gears to start the car.

Working : A battery works on the oxidation and reduction reaction of an electrolyte with metals when two dissimilar metallic substances , called electrode are placed in a diluted electrolyte , oxidation and reduction reaction take place in the electrode 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 reduction reaction , another electrode gets positively charged called anode . Here cathode forms the negative terminal wheras anode from the positive terminal of a battery.

Here actually when two dissimilar metal or metallic compound are immersed in an electrolyte , there will be a potential difference produced between the metals or metallic compounds . Hence causing the flow of current which is due to potential difference . When some specific compounds are added to water , they get dissolved and produce negative and positive ions . This type of compound is called an electrolyte .

FUSE :

Purpose : An electric fuse is a safety device which limits the current flowing in an electric circuit . When the current in the circuit increased beyond the limit , fuse burns and it saves different electrical appliances . The use of fuse safe the circuit and appliances connected in that circuit from being damaged . It is a short piece of wire made of an alloy of lead and tin . If the current passing through the fuse exceeds the safeguard limit , the heat produced melts the fuse and this breaks the circuit .

Working : The primary use of an electric fuse is to protect electrical equipment from excessive current and to prevent short circuits or mismatched loads. Electrical fuses play the role of miniature circuit breakers. Apart from protecting equipment , they are also used as safety measures to prevent any safety hazards to humans . The fuse wire in an electrical fuse ois selected in such a way that it does not face any damage when the normally stipulated amount of current flows through the circuit.

Under normal conditions , the fuse wire is a part of the circuitry , contributing to a complete loop for charges to flow through it . However , when an excessive amount of current flows through the fuse wire , the heating effect of the current causes the fuse wire to melt. This is because the fuse wire is chosen such that it has a low melting point. This causes the loop to break thereby stopping the flow of charges in the circuit. It is important to select a fuse that is properly specified for the circuit . For example , if underrated fuse is used then it will fail under normal condition causing breaking of circuit loop . If it is overrated then it will not break the circuit when required and cause equipment damage .

3. GIVEN : Full load current = 10 A

For individual circuit , the fuse rating should be 1.5 times of the full load current

therefore Fuse rating = 1.5 *full load current = 1.5*10 = 15 A

Answer : so fuse rating for full load current of 10 A is = 15 A

4. GIVEN: Power = 500 W

assume battery voltage = 12 V

Since Power is 500 W so Energy in an hour is

Energy = 500 Wh = 500 VAh

We know that

Capacity of battery = Energy / battery voltage

Capacity of battery = 500 / 12 = 41.66 Ah

Answer : So the recommended battery capacity is = 41.66 Ah

5. Here Light and Horn is connected in parallel connection to each other in parallel connection voltages are same and here both light and horn requirement is 12 V to operate . In parallel connection electric current flow through multiple path in parallel circuits and component of a parallel circuit will have a constant voltage across all ends .It means both end points are connected to each other means both the node are connected to each other and to the common node voltage source because in parallel connection, every unit that connected to parallel circuit gets an equal amount of voltage. It is easy to connect and disconnect a new element without affecting the working of other elements especially in case of any fault in the circuit so thats why light and horn are connected in parallel .

6. Here Ammeter and Fuse is connected in series connection because the current flow here in these two element is same that is constant current is flowing in both ammeter and fuse here ony one node is connected to both ammeter and fuse. Since ammeter is a measuring device so inorder to see the correct current flow reading we connect the battery in series with ammeter. Since fuse is a safety device so inorder to protect from over current we connect battery and fuse in series connection so when the fuse blows it will open the entire circuit and stop current through the component so that why we connect ammeter and fuse in series.