Abstract: A service transport unit for providing utilities to a parked aircraft, by way of a utility bundle, comprising a box attached to a passenger loading bridge, at least one slider and corresponding utility bundle tracker slidably mounted within the box wherein the utility bundle is fixed to the outboard terminus of the slider. The slider is mounted in the box and affixed to the passenger loading bridge so that it is pulled from within the container by extension of the passenger loading bridge, and pushed back into the box when the bridge is retracted. The utility bundle is passively extended and retracted by movement of the slider. The slider and utility bundle tracker also serve to guide the utility bundle and prevent it from tangling or kinking during movement of the passenger loading bridge.

Abstract: A simplified driver circuit for solid-state switches, comprising a main drive circuit and an adaptor circuit. The main drive circuit is powered only by the normal switch control signal input and by an external, regulated power supply commonly used by the equipment controls. No individual power supplies are used for the driver. The main circuit incorporates precise circuits for shaping and directing the input control signals, exceptionally high voltage isolation to avoid transmission of harmful noise and a circuit for delivering the required gate drive to a field-effect-transistor switch. The adaptor circuit connects to the output terminals of the main circuit, and modifies the drive signal to that required for a bi-polar transistor or a silicon controlled rectifier.The invention circuit is characterized by its use of few precise components, its high noise isolation and low power dissipation.

Abstract: A control system for poly-phase power inverters that uses feedback sensed voltages and currents to control the switching of solid state power switches in the inverter bridges, producing a nearly ideal sinewave voltage output regardless of load induced or switching harmonic voltages. The system operates in combination with the inverter power switches and switch drivers, particularly incorporating a digital programed optimal controller with virtually no delay in implementing the feedback control, and automatically correcting for any sensed line voltage distortions. The system inherently provides a high recovery speed for voltage transients.

Abstract: A method is described for controlling synchronous motor torque, utilizing a three-phase switch connected in a circuit to the input of a polyphase synchronous motor, and a switch control circuit. The switch control circuit senses the AC voltages input to the synchronous motor and produces signals that open and close the three-phase switch in phase with the input motor voltage, producing positive motor torque during normal operation. If input AC power is lost, the switch control circuit acts to prevent a reverse flow of high current from the motor from entering the power source bus. When input power, after a short time, returns, the switch control circuit acts to close the three-phase switch in such a manner as to permit only real power applied to the synchronous motor and thus positive torque that accelerates the motor speed and quickly restores the motor to synchronism with the input power source.

Abstract: A polyphase AC current limiting circuit, which incorporates improvements in control methods and circuitry that operate to avoid high rates of current change which occur upon initiation of a branch load fault and when the branch load fault is suddenly cleared. This "soft" start and "soft" load-off characteristic, reduces the voltage transients imposed on the AC power source and bus to relative insignificance compared with the voltage transients imposed by prior art current limiting circuits. The invention AC current limiting circuit comprises a high impedance circuit connected in parallel with a low impedance circuit, a load-off circuit connected in shunt with the device output power lines, and a control means for controlling the switching devices.

Abstract: An output frequency control circuit is mounted on the rotating shaft connecting a motor and generator. The motor-generator system includes exciter circuits, an input power factor control and an output voltage regulator. The input power factor control ensures that the motor input power factor is unity, which is desirable for motor control. The frequency control circuit responds to variations in the AC power source frequency by generating low frequency excitation to boost or buck the operational speed of the machine, causing the generator output frequency to remain constant at a selected frequency output irrespective of input power source frequency variation. The output frequency may be selected over a given range from a control panel adjustment pot.The major innovation is that the entire frequency control circuit is shaft-mounted and requires no slip-rings or magnetic transformers for signal transfer, thus reducing the possibilities of mechanical failure.