Electrical single failure analysis of LOFT 50 ton polar crane, 10 ton auxiliary hoist, and 4000 lb supplemental hoist

The report analyzes the single failures that could occur in the electrical drives of the LOFT 50 Ton Polar Crane, 10 Ton Auxiliary Hoist and 4000 lb Supplemental Hoist. A component failure analysis is provided for all functional subassemblies in the electrical control system. Failures resulting in adverse motor performance were assigned three consequence levels, and three failure probabilities, and were included in a fault tree analysis. Recommendations are made to reduce the consequences of the drive failures. Unusual firing of Trolley Drive Generator Field SCR's was investigated and a recommendation to eliminate the problem is made