Abstract: A continuous ribbon resistor element having a plurality of conjunctive lengths alternately connected by reflexes is supported in a frame comprised of silicon bonded laminated mica. The ribbon elements are formed with a single, flat convolution center offset to one side of an original plane and lateral portions offset to an opposite side of the plane, joined to the center offset by transition portions such that the centroid for any transverse cross section lies on the original plane. The offsets originate at flat end portions near the reflexes and have maximum offset intermediate the ends. Metal members are received in openings of the laminated mica insulators to receive threaded fasteners when attaching an insulator in edge-wise relationship to another. Thermally conductive termination connections are brought outside the frame and airflow passageway to remove from the passageway the additional heat otherwise absorbed by the terminals.

Abstract: An improved annular resistor, suitable for use in a diesel electric locomotive dynamic braking system and similar applications comprising an assembly of similar arcuate segments. Each resistor segment has a supporting frame (11, 13) and a continuous resistance ribbon (53, 55, 57, 59) having a plurality of reflexed radial extensions between the two parts of the frame, electrically isolated from the frame. To allow expansion and contraction of the ribbon, U-shaped folds of the ribbon are mounted on pin supports (51). The pin supports are mounted to insulator blocks (27, 29, 37, 39), and are set so as to position the ribbons in a zig-zag or chevron pattern, in order to enhance cooling and improve the flow of air over the ribbon surfaces. Three terminals (67, 73, 75) are provided on each segment to allow part of the resistance of each segment to be removed from the circuit.

Abstract: A dynamic braking resistor as shown and claimed in U.S. Pat. No. 2,680,178 in which the insulator blocks (226) in this new disclosure are formed of a hot-molded organic compound instead of steatite or asbestos. This allows the insulator blocks to be securely mounted to the frame (210, 212), and allows the elimination of the springs, spring cups and pressure plate. In addition, the extra insulative mica sheet required by the above patent is eliminated without loss of protection from short circuits. However, in order to protect the insulator blocks from the heat generated by the resistor ribbons (218, 220), the support clips (232) are made longer to allow more expansion of the ribbons and to hold the ribbons further away from the insulator blocks. In an alternative embodiment, three resistor ribbons (234, 236, 238) are employed, and each support clip (240) supports one reflex bend of all three ribbons.

Abstract: An annular resistor, suitable for use in a diesel electric locomotive dynamic braking system and the like, having a supporting frame including spaced inner and outer annular frame portions and a continuous resistance ribbon having a plurality of bent-back radial extensions therebetween and in electrical isolation therefrom. U-shaped folds of the ribbon are mounted on pin supports allowing contraction and expansion of the ribbon. The pin supports are mounted to insulator blocks which may be selectively positioned on the frame, when two or more are stacked, to vary ribbon alignment and hence convective cooling. The resistor is comprised of severally replaceable identical component quadrants.

Abstract: A system for protecting an electrical resistor, such as, for example, the dynamic braking resistor of a D.C. traction motor used in a diesel-electric locomotive, from burn-out in the event of a malfunction such as a cooling fan failure or air blockage, over-load, high ambient temperature, etc. Such protection is afforded by a noise-immune system that continuously monitors the resistor temperature and provides an output signal when the resistor temperature reaches a predetermined level above its normal operating temperatures short of an unsafe level. This is done by sensing the change in resistivity of the resistor with change in temperature thereof to provide a first control signal. A second control signal proportional to the current in the resistor is obtained and compared with the first control signal to obtain the aforesaid output signal proportional to the resistor temperature above ambient temperature.