Project - Analysis of a practical automotive wiring circuit

1. The various major elements in the above automotive wiring diagram are as follows :-

POWERTRAIN + SOURCE	MEASURING DEVICES	SAFETY DEVICES AND AUXILIARY DEVICES
Battery	Fuel Tank Unit	Current and Voltage Regulator
Ignition Switch	Fuel Guage	Fuse
Starter	Ammeter	Beam lights x4
Ignition coil		Horn
Breaker		Stop Light Switch
Distributor		Tail Stop x2
Generator		Dome Light Switch
Spark Plugs		Dome Light
		Light Switch
		Foot Selector Switch
		Parking Lamp x2
		Sealed Beam X2
		Junction Block

2. The purpose and working of three elements from the above circut diagran are as follows are as follows:-

a. Ignition Coil:-

Purpose:- The purpose of ignition coil is to produce spark at the spark plug for it to combust the air fuel mixture to power on the engines

Working:- The ignition coil is low current high voltage transformer i.e it contains primary and secondary coil with primary coil having less windings and secondary coil having more windings and by using the electrical energy supplied by battery to create a high voltage current for a short while to create spark.

b. Gas Tank Unit :-

Purpose:- The purpose of the gas tank unit is to send the informtion of amount of fuel present in the tank to the fuel guage. Here mechanical to electrical conversion is happening.

Working:- The gas tank unit consists of a float connected to a thin metal rod and the end of the rod is mounted on a variable resistor . And the end of the variable resistor has a strip which is connected to the ground on one side. A wiper connected to the guage moves across the the resistor conducting current from the guage to the resistor. When the tank is full the wiper will be near the grounded posistion of the resistor thus allowing more current to flow but as the fuel level starts to dips the wiper position moves away from the grounded position and the resistance increases thus allowing less current to flow across. Hence this way it sends the fuel level to the fuel guage .

c. Junction Block :-

Purpose: - The purpose of junction block is to provide electrical power to various systems in a tidy manner thus preventing short circut, eliminating wire splicing and to conserve panel space.

Working :- It is a insulated frame that houses 2 or more wires together. It consists of a clamping component and a conducting strip. The insulating body of a junction block houses a current carrying element It also provides a base for clamping element so it acn be connected acoss various devices.

3. The fuse rating is decided upon confirming what is the full load total steady current flowing throught the circut and the ambient temperature around the fuse. Since the battery is a DC source where the current flow across the load will be constant and considering the temperature to be ambient i.e 25 degree celsius then the fuse rating should be selected as to be 135% of this value (taken to the next standard value).

So for 10 Ampere steady state current at nominal temperature the fuse rating should be 15 Amperes or higher[10 amps x 135% = 13.5 amps, the next larger standard size is 15A]. We can go with 20 A depending the wire ratings . A 20 Ampere or higher fuse could also be used considered the wirings can carry higher currents as well without getting damaged.

4. The voltage battery capacity for a 500W of load depends on multiple factors such as backup time , input voltage required to maintain the load for a given amount of time

So the formula interrelating all these are as follows:-

Backup Time (in hours) = Battery Capacity (in Ah) X Input voltage (V) / Total Load (in Watts)

Suppose,

The input voltage requirement is 12 V, and the backup we need is for 6 hours and the load is 500W we can calculate the capacity of the battery by above formula which will be 250Ah .

As shown above depending on input voltage required and backup time provided for a 500W load we can select the appropriate battery required .

So for powering a 500W load for 6 hour the voltage and the battery requirement is 12 V 250Ah .

5. The two elements which are connected in parallel are the Sealed Beams and the Parking lamps. the two are connected in parallel because if they were connected in series then failure of one lamp would have resulted in failure of the other lamps , so in parallel that issue can be avoided and if one lamp gets damaged it won't efect the other lamps.

6. The two elements which are connected in series are the Gas tank unit anf Fuel guage. They are connected in series so that the same magnitude of current can be supplied to the Gas tank unit which has the variable resistor so that any changes in fuel readings will vary the resistance across the variable resistor which inturn will change current readings as the increase in resistance will restrict more and more current flow across the circut which will help in accurately identifying the amount of fuel fuel present in the tank .