What is the main purpose of the insulator in a spark plug?

The main purpose of the insulator in a spark plug is to isolate the electrical current. In a spark plug, the insulator is typically made from materials such as ceramic that have high electrical resistance. This design ensures that the electrical charge generated by the ignition system can be effectively transmitted from the center electrode to the ground electrode without any leakage. By maintaining this isolation, the insulator allows for the necessary high voltage to create a spark across the electrodes, igniting the air-fuel mixture in the combustion chamber.

While the insulator may indirectly assist in supporting the electrodes or resisting corrosion, its primary function revolves around electrical isolation. This role is crucial for the spark plug to operate efficiently and reliably under the harsh conditions found in an engine, which includes exposure to high temperatures, pressure, and potential contaminants.