Method and apparatus for cooling electrical fuses

The present invention generally relates to cooling systems for electrical equipment. More particularly, the present invention relates to cooling electrical protective devices such as fuses that are attached to electrical terminals. Electrical power converter units are vital and expensive components used in a variety of electric power system applications such as metal rolling mills and transportation systems. Power converters must be cooled to maintain their proper operating temperature. In a typical air-cooled power converter unit, heat generated by the unit is removed by free or forced convection to the ambient air to maintain the unit's operating temperature within an acceptable range. Although some units are air-cooled, higher power units often generate too much heat to be sufficiently cooled by free or forced convection of heat to the ambient air. Consequently, such high power units may be liquid-cooled. Power converter units typically utilize auxiliary devices. In air-cooled units, such devices are usually sufficiently cooled by free convention (also referred to as passive cooling) or forced convection (also referred to as active cooling) of heat to the ambient air. However, auxiliary devices on liquid-cooled units, may not be sufficiently cooled by the air. One type of auxiliary device that may require additional cooling when attached to a liquid-cooled unit, or even a high-powered air cooled unit, is the electrical fuses or fuse arrays. The purpose of fuses is to isolate the power converter circuits or other electrical components and equipment during an electrical fault event by melting their elements, severing the electrical circuit, and stopping the flow of electric current. This isolation limits the damage from high electrical currents during a fault. Since the fuses produce waste heat in normal operation, they must be cooled to maintain temperature limits for proper power converter protection and fuse life. When a higher-powered unit is designed, additional fuses may be added to an existing fuse array to help increase the power rating, but the fuses may no longer be electrically coordinated with the power converter. The fuses" elements must be coordinated, with respect to thermal capacity and arc voltage, with the power converter components they are protecting. Thermal capacity electrical coordination is the coordination of thermal capacity of the fuses with the power converter electrical conductors (which may be calculated by electrical current