Project - Analysis of a practical automotive wiring circuit

1. Identification of Major Elements in the Diagram

No. Element

1 Battery

2 Starter

3 Generator

4 Current and Voltage Regulator

5 Ignition Switch (IGN. SW.)

6 Distributor

7 Ignition Coil

8 Breaker

9 Headlamps (Scaled Beam)

10 Parking Lamp

11 Horn

12 Foot Selector Switch

13 Ammeter

14 Dome Light and Switch

15 Tail and Stop Lights

16 Fuel Gauge and Gas Tank Unit

17 Plate Light

18 Fuse

19 Beam Light Switch

20 Horn Button

2. Purpose and Working of Any Three Elements

(a) Generator

Purpose: Converts mechanical energy from the engine into electrical energy (DC) to charge the battery and run electrical loads.

Working: Driven by the engine belt, it generates DC electricity. A voltage regulator controls its output.

(b) Ammeter

Purpose: Shows the direction and magnitude of current flowing into or out of the battery.

Working: If current flows to the battery (charging), the needle deflects in one direction. If current flows from the battery (discharging), it deflects the other way.

(c) Fuse

Purpose: Protects electrical circuits from over current.

Working: If the current exceeds a safe limit, the fuse melts and breaks the circuit, preventing damage or fire.

3. Fuse Rating for 10 A Load

To choose a fuse:

Fuse Rating=Load Current×1.25

Fuse Rating=Load Current×1.25=10

 A×1.25=12.5

 A=10A×1.25=12.5A

Recommended fuse rating = 15 A

4. Battery Voltage and Capacity for 500 W Load

Given:

Load = 500 W

Battery Voltage = 12 V

Current (I)=PV=500*12≈41.67

 A Current (I)=VP​=12500​≈41.67A

To find battery capacity in Ah:

Assume run-time of 1 hour:

Capacity (Ah)=Current×Time=41.67×1=41.67

 Ah Capacity (Ah)=Current×Time=41.67×1=41.67Ah

Recommended battery: Voltage: 12 V

Capacity: At least 50 Ah

5. Two Elements Connected in Parallel

Example: Horn and Parking Lamp

Because, Both receive a full 12V supply.

They can be operated independently

6. Two Elements Connected in Series

Example: Ammeter and Fuse with the Battery

Because, the series ensures that all current from the battery passes through these protective and monitoring components.

An ammeter must be in series to measure total current.

Fuse must be in series to interrupt the current in case of a fault.