The Altronic CPU-XL VariSpark is a 24-VDC-powered digital ignition system for large gas engines and integral compressors. It combines the reliability and operating simplicity of first- and second-generation ignition systems such as the II-CPU and CPU-2000, with Altronic’s newly-patented spark control capability and system diagnostics. Combustion assurance across a wide range of operating and incylinder conditions is the goal of the CPU-XL system. The CPU-XL system stretches the envelope of successful operation, allowing combustion to take place under difficult circumstances, such as operating near the lean misfire limit for emissions, under lighter loads, or on engines that mix the air/fuel charge poorly. This is possible through the introduction of a controllable, selectable spark profile, optimized for those conditions, a Directed Energy spark. By choosing one of eight waveforms, including several which can deliver secondary current levels as much as twenty times that of a conventional capacitive discharge spark, the secondary voltage and current delivered to the spark plug and air/fuel mixture can be matched—and dynamically adjusted—to meet the operating requirements and conditions of the engine, thus assuring combustion. Supported by Altronic’s discharge diagnostics, the CPU-XL VariSpark system delivers an unparalleled combination of features and capabilities. To insure a high level of convenience and a minimum level of new product training, the operating philosophy and functionality is very similar to other Altronic digital ignitions, including the CPU-2000. The CPU-XL VariSpark incorporates modular system construction, including standard system harnesses with a unique ignition coil/ EZRail combination. The availability of all of these components as purchased parts limits on-engine fabrication and allows for simpler system troubleshooting.