High-voltage fuse cutout

An improved fuse tube for a fuse cutout usable to interrupt low and high fault currents, the fuse tube being elongated and having an ablative-arc-extinguishing-material-containing bore formed longitudinally therethrough between a first closed end and a second open end;

• a fuse link being insertable into the bore, the inserted fuse link having an ablative arc-extinguishing-material-containing sheath surrounding a stationary terminal nearer the first bore end, a terminal movable away from the stationary terminal toward the second bore end through the sheath, and a fusible element normally connected between the terminals;
• an arc established between the separating terminals after the fusible element becomes disintegral decomposing one or both of the arc-extinguishing materials to effect the rapid evolution therefrom of large amounts of de-ionizing, cooling and turbulent gases, which are exhausted from the second bore end and which extinguish the arc;
• wherein the improvement comprises:
• a conductive chamber in and generally coaxial with the bore, the chamber being electrically connected with the stationary terminal at least during the establishment of a high fault current arc, the chamber generally coaxially surrounding a portion of the sheath of the inserted fuse link and having one terminus extending beyond the movable terminal thereof in the direction of the second bore end, the sheath remaining integral during the establishment of a low current arc which is elongated between the terminals and disintegrating after the establishment of a high fault current arc which is elongated first between the terminals while the sheath is integral and then between the movable terminal and the chamber after the sheath disintegrates;
• and
• a mild taper formed in the bore so as to have a smaller cross-section at its inception intermediate the bore ends and a greater cross-section at the second bore end, the included angle and length of the mild taper being selected to obviate stagnation of the gases within the bore.

An improved fuse tube for a fuse cutout usable to interrupt low and high fault currents, the fuse tube being an insulative, elongated member having a sufficient length relative to the phase-to-ground voltage of a circuit to which the cutout is connectable and having a longitudinal bore lined with an ablative arc-extinguishing material, a first end of the bore being closed and a second end of the bore being open;

• a fuse link being insertable into the bore near the first end thereof, the inserted fuse link having a sheath containing an ablative arc-extinguishing material which surrounds a stationary terminal nearer the first bore end, a terminal movable away from the stationary terminal toward the second bore end through the sheath and the bore, and a fusible element which is rendered discontinuous by a fault current in the circuit, the fusible element being normally connected between and preventing separation of the terminals;
• the stationary terminal being normally electrically connectable to one point of the circuit and the movable terminal being continuously electrically connectable to an opposed point of the circuit;
• an arc established and elongated between the separating terminals incident to a low fault current rapidly evolving from the sheath arc-extinguishing gases;
• an arc established and elongated between the separating terminals incident to a high fault current first distintegrating the sheath and then rapidly evolving from the bore arc-extinguishing gases;
• all arc-extinguishing gases being exhausted from the second bore end;
• wherein the improvement comprises:
• a conductive chamber in and generally coaxial with the bore, the chamber being electrically connected with the stationary terminal at least during the establishment of a high fault current arc and generally coaxially surrounding the sheath of the inserted fuse link, one terminus of the chamber extending beyond the movable terminal of the inserted fuse link in the direction of the second bore end, the other terminus of the chamber being closer to the first bore end, and
• a mild taper formed in the bore so as to have a smaller cross-section at its inception intermediate the bore ends and a greater cross-section at the second bore end,
• following disintegration of the sheath, one end of the high fault current arc transferring from the stationary terminal to the chamber and being thereafter elongated between the one terminus and the movable terminal to limit the amount of arc elongation which can be effected within the bore, the included angle and length of the mild taper being sufficient to obviate the stagnation of gases within the bore.

An improved fuse tube for a fuse cutout usable to interrupt low and high fault currents, the fuse tube being elongated and having an ablative-arc-extinguishing-material-containing bore formed longitudinally therethrough between a first closed end and a second open end;

• a fuse link being insertable into the bore at the first end thereof, the inserted fuse link having an ablative arc-extinguishing-material-containing sheath surrounding a stationary terminal nearer the first bore end, a terminal movable away from the stationary terminal toward the second bore end through the sheath, and a fusible element normally connected between the terminals;
• an arc established between the separating terminals after the fusible element becomes disintegral being elongated by the separation and simultaneously decomposing one or both of the arc-extinguishing materials to effect the rapid evolution therefrom of large amounts of de-ionizing, cooling and turbulent gases, which are exhausted from the second bore end and which extinguish the arc;
• wherein the improvement comprises the combination of:
• conductive means electrically connected with the stationary terminal and in the bore for decreasing the extent to which a high fault current arc may be elongated within the bore;
• and
• a mild taper formed in the bore so as to have a smaller cross-section at its inception intermediate the bore ends and a greater cross-section at the second bore end.