Abstract: A fault tolerant isolation system providing fault tolerant electrical isolation between different components receiving power from separate power sources regardless of which of the power sources fails. One power source provides operating voltage to an isolation device, which is a transceiver, buffer, quick switch, etc. The other power source activates a transistor switch coupled to the output enable input of the isolation device, and a current limit device is provided between the output enable and power inputs of the isolation device. In this manner, failure of either power source disables the isolation device and therefore provides fault tolerant isolation between the devices on either side. In the preferred embodiment, the isolation device acts as a high impedance open switch if its power is removed thereby isolating the devices on either side.

Abstract: This invention relates to an improved laser printer power supply that maintains 24-, 12-, and 5 volt DC power to run exhaust fans for a brief period after the power switch is turned off. These fans remove undesirable ozone from the photo-conducting print drum so as to extend the life of the photo-conductor. The circuits utilize a timer circuit and an optically isolated photo-diac to turn a power triac on and off.

Abstract: A solar power system supplying A.C. voltages at 60 Hz as required for irrigation control with frequency precision and voltage levels in accordance with specifications for off-the-shelf irrigation timers and controls.

Abstract: The invention is a two-level power system for electrically powered aircraft sub-systems. An aircraft engine (2) drives a three phase generator (30) at a variable speed. The output of generator (30) is primary variable-voltage/variable-frequency (VV-VF) power which is utilized by various aircraft subsystems. A portion of the primary VV-VF power is converted to constant voltage-constant frequency (CV-CF) power by an inverter (31) which includes front end rectification. The CV-CF power is then available to selected aircraft subsystems while portions of the CV-CF power are converted by rectifier (32) and transformer-rectifier (33) into 270 vdc and 28 vdc power, respectively, which power is also then available to aircraft sub-systems.

Abstract: Two cascaded induction machines provide asynchronous power transmission between two independent generating networks. The shafts of the two induction machines are mechanically connected for concurrent rotation and the rotor windings of the two machines are electrically connected in a reverse phase sequence. The cascaded induction machines are geared to a relatively low power variable speed drive which accurately controls the position and rotation of the shafts. A control system supplies low frequency excitation current for the variable speed drive and is capable of continuous operation through zero frequency to reverse the direction of rotation. The control system determines the level of power flow within the induction machines and is unresponsive to the difference in frequency of generation of the two generating networks so that the power flow is controlled even under transient load conditions.