The ASG system uses electronics to actively ground the shaft to the hull through a slip ring brush assembly. The system measures the shaft to hull potential through one slip ring assembly, and then uses this signal, after amplification, to control a high current power supply which draws a current out of the shaft through a second slip ring assembly. The circuitry reduces the variation in shaft-to-hull resistance, which in turn results in small variation in the current between the cathodic protection anodes and the hull. The ELFE signature is then virtually eliminated.

Active Shaft Grounding (ASG) virtually eliminates the underwater Extremely Low Frequency Electromagnetic (ELFE) signal that originates from modulation of current passing through a ship's shaft and shaft bearings. As shown in the interactive graphic below, the ASG system, when activated, provides for a low resistance path for the current to bypass the shaft bearings.