Project - Analysis of a practical automotive wiring circuit
Question 1 - Identify each of the major elements in the above automotive wiring diagram.
Answer -
1. Generator
2. Battery
3. Current and voltage regulator
4. Fuse
5. Distributor
6. Foot selector switch
7. Starter
8. Breaker
9. Junction box
10. Ammeter
Question 2 - Explain the purpose and working of any three elements briefly.
Answer -
1. Generator -
Purpose - The purpose of generator is to charge the battery. Generator is the device that converts mechanical energy into electrical energy.
Working - Electric generator works on Faraday's law of electromagnetic induction. This law states that whenever a conductor is placed in a varying magnetic field, EMF is induced and this induced
EMF is equal to the rate of change of flux linkages. This EMF can be generated when there is either relative space or relative time variation between the conductor and magnetic field.
This exact same effect is obtained by using bunch of parts like prime mover, permanent magnets, brushes, voltage regulator etc.
2. Battery -
Purpose - Battery is a source of electric power and it is used to power bunch on components in EVs.
Working - A battery is a collection of cells. The chemical reactions occuring in the cells of a battery results in the flow of electricity in the circuit. It consists of an anode, a cathode and electrolytic solution.
Anode - It is a negative electrode that emitts electrons to the external circuit. It gets oxidized during a chemical reaction.
Cathode - It is positive electrode that gains electrons from the external circuit. It gets reduced during the chemical reaction.
Electrolyte - It is a medium that facilitates transfer of ions between anode and cathode during a chemical reaction.
3. Fuse -
Purpose - Fuse is a safety device that protects the circuit and its components from excessive current that has potential to cause fatal consequences.
Working - The heating effect of electric current is the basis for how an electric fuse operates. It is connected to the gadget in series. A piece of wire with a suitable melting point, such as aluminium, copper, iron, lead, etc., is what makes up a fuse. The temperature of the fuse wire rises if a current greater than the designated value passes through the circuit. Fuse wire melts as a result, cutting off the circuit.
Question 3 - If the total load is 10A from battery, what should be the fuse rating?
Answer -
Taking battery voltage as 12 V.
Given data -
I = 10 A
Power (P) = Current (I) X Voltage (V)
P = 10 X 12
P = 120 W
We generally consider 150% to 200% more fuse rating than actual power rating.
Here we will consider 150%.
Therefore,
Fuse rating power = 120 X (150 / 100)
Fuse power rating = 180 W
Therefore,
I = 180 / 12
I = 15 A.
Hence, fuse rating for total load of 10 A from battery should be 15 A.
Question 4 - If 500W is the load, what is the voltage and capacity of battery you recommend?
Answer -
(Recommanded voltage is 12 V.)
We will consider that a particular battery should be able to give 500 W of power contunously for at least an hour in a single charge.
Power (P) = Current (I) X Voltage (V)
500 = I X 12
I = 41.66666667 A.
Battery Capacity = Current X Duration
Battery Capacity = 41.66666667 X 1
Therefore,
Battery Capacity = 41.66666667 Ah.
Hence recommanded voltage and capacity is 12 V and 41.67 Ah respectively.
Question 5 - Identify any two elements which are connected parallel to each other. Why they are connected in parallel?
Answer -
Parking lamp and horn are connected parallel to each other.
Reason - When two or more components are connected parallel to each other the potential difference between the components is same in magnitude and they alsohave identical polarities.
The same voltage is applied across all the components connected in parallel to each other. Therefore each of those components can function independently.
Question 6 - Identify any two elements which are connected in series. Why they are connected in series?
Answer -
Battery and fuse are connected in series with each other.
And also all other utility compoents are in series with fuse.
Reason - Fuse is a safety device means it is meant to protect other components in the circuit from excessive current. Components connected in series are connected along single electrical path and each components has same current through it equal to the current through the network. The voltage across the network is equal to the sum of the voltages across each component. As fuse is in series with battery it can trigger (melt) as soon as it senses excessive current as per its rating. Had it not been done then though the fuse could have triggered but excessive current would also have gone to all the other components in the circuit severly damaging them.