Abstract: A ground fault detector for use in resistance grounded electrical systems. In one embodiment, the system includes a digital processor to monitor an electrical parameter of the resistance to determine and indicate whether a ground fault has occurred. Data regarding the ground fault occurrence can then be digitally stored transmitted, or processed, such as by an external computer. In another embodiment, the ground fault detector includes a filter to remove the harmonic components of the monitored electrical parameter, to avoid false alarms. In addition, in another embodiment, the ground fault detector can also determine whether a high harmonic condition is present in the monitored electrical system. The phase of the electrical system can be grounded by pressing a test switch, thereby causing a ground fault and allowing the harmonic components of the signal in the electrical system to be monitored.

Abstract: A resistor comprising a substantially continuous resistor element being formed into a plurality of element panels with each panel having at least two holes provided therein. Adjacent element panels are connected in series by a bend in the resistor element. At least two support tubes comprising an insulating material are provided to support the resistor element. A plurality of conductive washers are provided adjacent each hole on both sides of each element panel to provide a conductive heat sink near each support tube hole in the element panels. Insulating washers are spaced between adjacent conductive washers. Two end walls are provided adjacent opposing sides of the resistor element to receive the support tubes.

Abstract: A high power resistor grid assembly formed of a plurality of stainless steel resistor U-shaped elements arranged in a substantially parallel relationship welded together in a continuous path. Each element comprising a slotted rectangular sheet in a U-shape having elongated curved embossments to prevent warpage of the element upon heating. Each U-shaped element has alternately a right and left leg offset to permit end to end attachments of elements while maintaining uniform spacing between the elements. The elements are supported by pairs of double insulated members which are affixed to the top and bottom of a frame with a floating end to permit expansion of the assembly upon heating and contraction upon cooling.

Abstract: A grid resistor assembly includes a plurality of flat grid resistor elements. Each element includes at least one open-ended loop having side portions and a tip end portion connected together through intervening strip portions of narrower width than the side portions to improve current carrying capacity and to provide for more even heating and heat dissipation. An assembly of such elements is particularly used as a resistor box in an electric, motor-driven, transit vehicle, such as a subway car, and is provided in a predetermined space envelope to perform predetermined electrical parameters.