Project - Analysis of a practical automotive wiring circuit

1) starter , generator , ignition coil , distributor , battery , junction box , horn , scaled beam , breaker .

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2) A) Generator :- it converts mechanical energy into electrical energy . it supplies power to a vehicle . it plays a major role in a vehicle for power source.

The main components of an electric generator can be broadly classified as follows:

• Engine
• Alternator
• Fuel System
• Voltage Regulator
• Cooling and Exhaust Systems
• Lubrication System
• Battery Charger
• Control Panel
• Main Assembly / Frame

Working principle :- 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.

B) Battery :- its helpful for all the electrical appliances even for starter also .

The main components of battery is classified as follows :-

• container
• cathode
• separator
• anode
• electrodes
• electrolyte
• collector.

Working principle :- 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 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.

The cathode forms the negative terminal whereas anode forms the positive terminal of a battery. To understand the basic principle of battery properly, first, we should have some basic concept of electrolytes and electrons affinity. Actually, when two dissimilar metals are immersed in an electrolyte, there will be a potential differences produced between these metals.

C) current and voltage regulator :-

Working of voltage regulator :-

A voltage regulator is a circuit that creates and maintains a fixed output voltage, irrespective of changes to the input voltage or load conditions.

Voltage regulators (VRs) keep the voltages from a power supply within a range that is compatible with the other electrical components. While voltage regulators are most commonly used for DC/DC power conversion, some can perform AC/AC or AC/DC power conversion as well. This article will focus on DC/DC voltage regulators.

Types of voltage regulators :-

There are two main types of voltage regulators: linear and switching. Both types regulate a system’s voltage, but linear regulators operate with low efficiency and switching regulators operate with high efficiency. In high-efficiency switching regulators, most of the input power is transferred to the output without dissipation.

Working of current regulator :-

The variable resistor is used to represent the actions of a current regulator. We will assume the variable resistor is automated and can auto-adjust its own resistance. When the circuit is powered, the variable resistor adjusts its resistance to compensate for changes in the current due to variation in load resistance or voltage supply. From basic electricity class, you should remember that when the load, which is essentially resistance (+ capacitance/inductance) is increased, an effective drop in current is experienced and vice versa. Thus when the load in the circuit is increased (increase in resistance), rather than a current drop, the variable resistor reduces its own resistance to compensate for the increased resistance and ensure the same current flows. In the same way, when the load resistance reduces, the variable resistance increases its own resistance to compensate for the reduction, thus maintaining the output current value.

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3) Fuse :- The normal operating current of the circuit is In order to select the right amperage of the fuse, we need to know the full-load steady-state current of the circuit at an ambient temperature of 25º C (68º F). Once the current value is determined, then a fuse rating should be selected as to be 135% of this value (taken to the next standard value).

operating voltage
The basic rule of thumb is that the voltage rating of the fuse must always higher than the voltage rating of the circuit that it is protecting.

operating ambient temperature
Ambient temperature is a fancy way of saying the “outside air” surrounding the fuse. Normally, the fuses are tested in "laboratory conditions" by the safety agencies such as UL and CSA. The lab conditions are almost always set at 25°C or 77°F. Unfortunately, most real world conditions are not those found in a laboratory. Fuses are heat sensitive devices meaning that it takes heat (via the overcurrent) in order to melt the fuse element inside the fuse. The more heat...the faster it takes to melt the fuse element...the less heat...the longer it takes to melt the fuse element. If a fuse will be subjected to a higher temperature than 25°C, then the fuse amperage will need to be increased as to compensate for the higher temperature (to avoid "nuisance tripping"). Likewise, if the fuse will be used at a lower temperature, then the fuse amperage needs to be lowered (or else it might never open). The rule of thumb is that for every 20°C higher or lower in temperature, the fuse should be re-rated higher or lower 10-15%. An example of a fuse re-rating when higher ambient temperatures are present

Normal full-load current: 1 Amp
Normal fuse sizing: 1.5 Amps (135% of full load current taken to the next higher standard rating)
Ambient Temperature: 65°C
Re-rating: Re-rating: 2 Amps (130% of normal fuse rating)

For this load 15A fuse is preferable .

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4) formula is (run time in hours) * (inverter wattage) = (total watts) / (DC volts) = amps required

we will take a standard 12 V battery.

the amount of energy stored in the battery is 500w

E = V *Q

Q = E / V

= 500 / 12

= 41.6 amps

for the 500w the 12v , the 41.6 amps battery capacity is preferable .

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5) horn , scalcd beam are connected in parallel connection . because they need a same amount of input power so thats why they are connected in parallel connection .

The reasons why different appliances are connected in parallel are:

• All the appliances get their rated voltage so that they function efficiently.
• All the components can have their independent switch to control them.
• If one appliance gets faulty, it doesn't affect the other appliances.

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6) battery to starter and starter to ammeter . these are connected in series connection . because starter need a high voltage and current but for the ammeter it doesnt want . this ammeter gets the reference current to the starter .

In series connections, the same current flows across all the branches of the circuits, but different voltage across it thus making the resistors to have different voltage across them. Each resistor or load will experience a voltage drop. The applied voltage is equal to the sum of the voltage drop across the different parts of the circuit. Voltage drop is proportional to the resistance current being the same throughout the circuit. When loads are connected in series, the loads will tend to have a common switch.

Advantages of Series Connection

• Less size of wire cable is required in series wiring.
• We use to protect the circuit to connect fuse & circuit breaker in series with other appliances.
• Series circuit don’t get overhead easily due to high resistance when more load added in the circuit.
• The lifespan of battery in series circuit is more as compared to parallel.
• It is most simple method of electrical wiring and fault can be easily detect and repair as compared to parallel or series-parallel wiring.

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