Intro
All Gas turbine engines use high energy igniter units for engine starting. They all have two high energy igniter units which each feed a separate igniter plug. they have an approx output of 12 Joules. It is sometimes necessary to prevent engine 'flame out', to have the ignition system selected in circumstances other than engine starting.
Use of high energy ignition systems on these occasions will cause the igniter plug to erode, shortening its working life dramatically.
All Gas turbine engines use high energy igniter units for engine starting. They all have two high energy igniter units which each feed a separate igniter plug. they have an approx output of 12 Joules. It is sometimes necessary to prevent engine 'flame out', to have the ignition system selected in circumstances other than engine starting.
Use of high energy ignition systems on these occasions will cause the igniter plug to erode, shortening its working life dramatically.
Direct Current high energy ignition unit
the high energy ignition unit works on the principle of charging up a large capacitor and then discharging it across the face of an igniter plug. The size of the capacitor makes it potentially lethal device, several safety factors have to be built into the high energy ignition unit so it is set to safety regulations. The high energy ignition unit is mounted on the side of the engine shown in the picture across. |
Igniter Plugs
There are two types of igniter plugs. The older version is similar to a piston engine spark plug, but has a bigger spark gap.
A more modern version of the igniter plug is the surface discharge ignite plug. The end of the insulator of the surface discharge igniter plug if formed from a semi-conductor material. the semi conductor material allows an electrical leakage to occur between the hot electrode to the body of the igniter which ionizes the surface of the semi conductor material and provides a relatively low resistance path for the energy stored in the capacitor.
The discharge takes the form of a high intensity flash-over from the hot electrode to the body of the igniter which only requires around 2,000 volts.
There are two types of igniter plugs. The older version is similar to a piston engine spark plug, but has a bigger spark gap.
A more modern version of the igniter plug is the surface discharge ignite plug. The end of the insulator of the surface discharge igniter plug if formed from a semi-conductor material. the semi conductor material allows an electrical leakage to occur between the hot electrode to the body of the igniter which ionizes the surface of the semi conductor material and provides a relatively low resistance path for the energy stored in the capacitor.
The discharge takes the form of a high intensity flash-over from the hot electrode to the body of the igniter which only requires around 2,000 volts.