MOLDED POTENTIAL TRANSFORMER Russian patent published in 2003 - IPC

FIELD: transformer engineering. SUBSTANCE: transformer has magnetic core, high- voltage winding, at least one low-voltage winding, and one high- voltage lead, all mounted in molded insulating case. Socket provided in its top part houses high-voltage fuse connected to high-voltage lead. Fuse has two bases, body of gas-producing material accommodating extension spring and low-power metal- film resistor that functions as fusible link. One of fuse bases has at least one hole opposing at least one hole provided in high-voltage lead and inner surface of the latter has annular slot facing hole in base and joined with lead hole. Rated value of resistor is found from expression where r_r,rtd is rated value of resistor, Ohm; P_r.rtd is rated power of resistor, W; is overpower factor of resistor affording operation of fuse within time t_pr; I_pt is current through fuse operating within time t_pr (found from time-current characteristic of fuse), A; I_Tr.1max is maximum permissible current of potential transformer high-voltage winding, A; I_r.rtd is rated current of resistor, A. EFFECT: enhanced reliability of protective gear. 1 cl, 3 dwg