Trade of Motor Mechanic - eCollege

Module 4 - Unit 1
Trade of Motor Mechanic - Phase 2 Course Notes
10
Basic Ignition Systems
A shield of soft iron surrounds the outer windings and the complete
assembly is inserted into a one-piece steel or aluminium container.
The container is then filled with special transformer oil, which
provides good electrical insulation and also permits rapid heat
dissipation.
The cap has two terminals, positive and negative, for external
connection to the primary circuit. The ends of the primary winding
are connected internally to each. Provision is also made externally
for a heavy insulated centre terminal to connect the high tension
coil lead to the distributor cap.
One end of the secondary winding is connected to this centre
terminal and the other end is connected to one end of the primary
winding. A rubber seal and a moulded insulated cap seal the assembly
in the container and the container edges are swaged over to bind
the coil into a compact vibration free unit.
Primary & Secondary Windings
The two main sections of an ignition system coil are:
Primary Windings and Secondary Windings
On a breaker contact points system:
The primary circuit is the low voltage side. It includes:
•
•
•
Power source from the battery
In some instances, ballast resistor
Primary windings connecting to:
•
•
•
Contact breaker points
Condenser
To earth thus completing an electrical circuit.
Revision 2.0 July 2007