Q. Briefly explain Automotive Ignition System?

Ignition systems in automobiles have been designed as a straightforward application of electrical transients. Figure shows a simplified ignition circuit for an internal-combustion engine. The primary inductance, current-limiting resistance, and capacitance forman underdamped series RLC circuit. Thus, when the points open, an oscillatory current flows through the primary, thereby inducing the required voltage in the secondary. The points form a switch, which opens and closes as the engine rotates, exactly at the instantwhen an ignition spark is needed by one of the cylinders. During the period when the points are closed, current builds up rather slowly in the primary winding of the coil, which consists of a pair of mutually coupled inductors, as shown in Figure. The current is interrupted rapidly when the points open. The resulting large rate of change of current induces a large voltage across the coil secondary, which is connected to the appropriate spark plug by the distributor. The resistance limits the current in case the engine stops with the points closed. Since the voltage across a capacitance cannot change instantaneously, the capacitor prevents the voltage

 across the points fromrising too rapidly when the points open. Otherwise arcingmay occur across the points, which in turn may get burned and pitted.