Abstract: A regenerative braking system includes a converter having a converter output and a converter input. The converter input is electrically connected to a traction motor. The system also includes a resistive grid electrically connected to the converter output. The resistive grid includes at least one grid resistor. The system includes a tap electrically coupled in parallel between the at least one grid resistor and a direct-current power bus.

Abstract: A composition for insulating a component may include between about 80 and about 99 percent by volume of a non-silicone-based insulating resin. The composition may also include between about 1 and about 20 percent by volume of magnesia trihydrate.

Abstract: The invention is a commutator for a high speed, high power DC traction motor having a rotor with a plurality of copper commutator bars having a V-shaped groove an axial end thereof, an electrically conductive retaining ring engaging the V-shaped grooves of the commutator bar, and means for exerting an axial force between the retaining ring and commutator bars to retain the latter against radial movement during high speed rotation of the rotor. Each of the commutator bars has an axial end face with a radially inwardly extending axial depression which joins an axially extending radial depression in a radially inner axial surface thereof adjacent the retaining ring. The retaining ring has an axial end face aligned with the axial end face of the commutator bars and an outwardly radially extending axial depression which joins an axially extending radial depression in a radially outer axial surface thereof adjacent the commutator bars.