Abstract: A conversion of a three-phase, four-wire power system to divert all zero-sequence current from the power system grounded-neutral source transformer and its phase and neutral conductors. A zero-sequence filter transformer such as a zig-zag transformer is installed, and the system neutral conductor and ground point are relocated from the neutral terminal of the source transformer to that of the zero-sequence filter transformer. A protection scheme operates to trip a main circuit breaker for zero-sequence filter transformer overloads or short circuits. The source transformer and its neutral circuit are thereby protected from the ill effects of zero-sequence currents.

Abstract: A system for use with electrical machines allows fast transfers to be made from one power source to another or fast reconnections to be made to a momentarily interrupted power source without subjecting the machines to unsafe voltage levels. The system short circuits the electrical machines to bring their residual voltage down quickly to a level at which the machines may be safely connected to a power source, and works with both induction and synchronous machines. No interlocking devices are necessary to the system, thus further speeding up fast transfer while minimizing the effects of inadvertent direct short circuiting of the power source.

Abstract: Protection of induction motors and generators is provided to allow rapid reclosure of the power supply or fast transfer from one power supply to an alternate supply. A switching sequence is disclosed in which motor stator windings are short circuited immediately following interruption of the supply voltage. Said short circuit quickly discharges to a safe value the energy stored in the rotor of the induction machine, allowing the short circuit to be removed and safe reconnection to the power supply to be accomplished without further delay.

Abstract: A wind energy conversion system for converting wind energy into controlled wind turbine torque comprising a wind turbine with an essentially horizontally disposed shaft, a means, rotatably mounted to a chassis, for sensing and reacting to wind turbine torque such that reaction torque acting on the means causes angular displacement of the means, a driven machine drivenly connected to the shaft of the wind turbine, and a means for adjusting wind turbine efficiency which is drivenly connected to the first mentioned means in such a way as to prevent continual angular speed thereof. Angular displacement of the first mentioned means provides the power for the last mentioned means to adjust wind turbine efficiency.

Abstract: Automatic torque control of wind energy conversion devices is provided through the utilization of turbine reaction torque. In the preferred embodiment, the frame of the driven machine is arranged to be rotatable through a limited angle. As rated torque of the system is exceeded, a force proportional to the turbine reaction torque is exerted by said frame to adjust the turbine aerodynamic configuration in such a manner as to reduce the torque error to substantially zero.