In a cooling system for cooling power electronics on a locomotive where the cooling system includes a finned heat sink that has air passing therethrough an airway passage to reach a plurality of fins where reducing airborne debris clogging of the plurality of fins is preferred, the heat sink includes at least one of a by-pass area having no fins located at an area where debris is expected to pass through the plurality of fins, a turning guide directing air between the plurality of fins at a specific location, a blockage reduction fin structure on at least one fin of the plurality of fins, and fins proximate within the inlet airway passage.