scope:

This specification covers the design, fabrication, and testing of a rotating shaft Electronic Grounding Unit (EGU). The EGU is one component of the Active Shaft Grounding System (ASGS) used on ships and submarines. The ASGS mitigates corrosion of the shaft, shaft seals, and bearings by providing an electronically controlled, preferential ground point for propeller and shaft currents to return to ships' ground. The ASGS, shown on figure 1, is comprised of two components, the EGU and the shaft contact grounding brush system. This specification covers the EGU only. The EGU uses feedback control to monitor the shaft-to-hull voltage and impress a current output between the shaft and hull to reduce the potential difference below a set point. The EGU interfaces electrically with the shaft through the shaft contact grounding brush system. Information on the grounding contact system can be found in 803-1749216, Cathodic Protection, Propeller Shaft, Grounding Brush.