Single Vent Small Bore Extra Heavy Duty Cutout

foreign [Music] EHD is the industry's first fuse cutout of its type in the extra heavy duty rating characterized by single vent small bore operation a fiberglass reinforced fuse tube positive closure and a unique thrust absorbing recoil design these characteristics assure positive protection and safe operation over the full range of faults from the minimum current required to melt the fuse to thousands of amperes free of null operating points and offering increased safety for personnel and equipment intensive application of Hubbard's integrated research and development facilities was required to design a single vent small bore cutout to solve the interrelated electrical and mechanical problems encountered in the extra heavy duty range and to prove performance superiority the confinement offered by a single vent small bore fuse tube provides the most efficient condition for fault current interruption the fuse tube of the Hubbard EHD cutout employs the smallest bore possible which will readily accommodate all fuse links up to and including the 100 ampere size any overload condition causing the fusible element to rupture draws an arc between the separating ends of the fuse link heat from this Ark generates gases from the vulcanized fiber walls of the tube due to the small bore confinement of these gases rapid expulsion action forces all conducting gases downward and out the single vent thus interrupting the current since low fault currents can generate only a small quantity of these gases in any fuse tube single vent small bore confinement maximizes the pressure for positive rapid expulsion action on the other hand high-level fault currents liberate a tremendous volume of these gases the resulting pressure would burst a single vent small bore tube if it weren't for another hover development the high strength fiberglass reinforced fuse tube control of the jet action thrust of single vent operation is accomplished by a unique recoil design protecting all parts of the cutout against the tremendous mechanical forces the coordination of this recoil maintains positive contact pressure throughout the interruption and prevents contact burning after the arc has been extinguished the upper end of the fuse tube separates from the Spring contact and the Dropout action leaves a visible isolating air gap components thoroughly tested mechanically and electrically ensure Optimum cutout quality strength of hardware porcelain columns and fastenings to withstand mechanical stress current carrying capacity of the electrical path to ensure cool operation at maximum continuous current repeated 60 Cycle flashover tests to assure insulation capable of withstanding normal system voltages under service conditions and impulse tests to determine ability of the cutout to withstand lightning surges positive interrupting ability throughout the extra heavy duty range without null operating points is the most significant single feature of Hubbard's EHD cutout whether the fault current is the minimum for fuse melting in the middle of the range or at the maximum rating single vent small bore operation assures positive clearing of the fault this series of high-speed camera runs made during the exhaustive testing of the cutout slows the action to demonstrate positive clearing throughout the range with the specimen refused witness again that last test in the series at a more normal speed the circuit is connected to deliver 10 000 amperes of asymmetrical RMS fault current operating at 7.5 KV the fault is to be initiated at voltage 0. we are starting the charge this is the five second warning five four three two one whenever we think of safe cutout operation we immediately think of the alignment on the pole he is interested in Easy removal of the fuse holder assembly working with a hook stick Simplicity of refusing using only standard tools and not requiring special links or cutout Parts in returning the cutout to operation the fuse holder can be reinserted only in its proper operating position the fuse holder trunions drop easily into the lower hinge the lower cam action plus the upper guide plate ensures positive closure the load brake lever can be added in service using the same fuse holder to mechanically break the link requires an upward thrust this maintains contact pressure until the link has been broken and the arc interrupted within the fuse tube safety even under the conditions of closing in on a fault the small confined cone of gases is directed downward and away from the linemen and away from equipment and lines in the overhead structure the Hubbard EHD cutout is rated at 100 amperes continuous current and has an interrupting capacity of 10 000 amperes asymmetrical RMS current at 5.2 and 7.8 KV and 8 000 amperes at 15 kV the Hubbard emblem on the fuse tube is your Assurance of a single cutout offering positive and safe protection against all faults from the minimum current required to melt the fuse to the maximum rating of the cutout 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