Diagnostic device for gas turbine ignition system

An ignition system having the ability to diagnose the state of health of an igniter plug of the system by monitoring an ignition waveform generated at a location in the system electronically remote from a high energy pulse at the igniter plug and environmentally isolated from the plug, the ignition system comprising:

• means for generating a series of the high energy pulses for initiating spark events at the igniter plug;
• means for communicating the high energy pulses to the plug;
• a series of the ignition waveforms created within the generating means in connection with the generation of the series of high energy pulses, where each of the waveforms is associated with one of the high energy pulses;
• a device for monitoring the series of waveforms and detecting abnormalities in the waveforms;
• and
• means for diagnosing the state of health of the igniter plug in response to the detection of the abnormalities in the series of waveforms associated with the series of high energy pulses.

An apparatus for providing to an engine control unit (ECU) a diagnosis of the health of an ignition system that ignites the fuel of a turbine engine, where the ignition system comprises an exciter that delivers to an igniter plug a series of high energy pulses, the apparatus comprising:

• a first detector for detecting persistent voltage levels for the high energy pulses that are less than a predetermined value representing a nominal minimum voltage generated by the exciter when it is healthy;
• a second detector for detecting persistent discharging of the high energy pulses at a rate much less than a predetermined rate representing a nominal minimum rate of discharge for the igniter plug when it is healthy;
• and
• a diagnostic output means responsive to the first and second detectors for indicating to the ECU (1) failure of the exciter when the first detector detects the voltages of the high energy signals persistently failing to exceed the predetermined value and (2) failure of the igniter plug when the second detector detects the discharge rates of the high energy pulses persistently failing to exceed the predetermined rate.

A diagnostic unit for use with a high energy ignition system for diagnosing the state of health of the system by monitoring an ignition waveform generated at a location in the system electronically remote from an igniter plug and environmentally isolated from the plug, the ignition system comprising an exciter of a capacitive discharge type for generating a series of high energy pulses for initiating spark events at the igniter plug for igniting fuel;

• a series of ignition waveforms formed by the discharge of the series of high energy pulses into the plug by way of a low-impedance cable, where each of the waveforms is associated with one of the high energy pulses;
• the diagnostic unit for diagnosing the health of the ignition system comprising:
• (1) a detection circuit for monitoring the series of waveforms and detecting abnormalities in the waveforms;
• and (2) a diagnosis circuit responsive to the detection of the abnormalities in the series of waveforms for distinguishing between at least the igniter plug and the exciter as the source of the abnormalities, thereby diagnosing the state of health of the system.