Abstract: An electrical power distribution system for an aircraft comprises a power source electrically connected to an electrical load and at least one circuit interruption device for interrupting current in the power distribution system. A distinguishing device is connected to the system for distinguishing a transient electrical event in the system from a steady-state level of electrical activity in the system, wherein the transient electrical event induces a potential difference across all or part of the distinguishing device. The circuit interruption device is operable to interrupt current flowing through the power distribution system if the potential difference across the distinguishing device exceeds a threshold voltage.

Abstract: In one aspect, the present invention provides an electromagnetic circuit interrupter for use in a high voltage direct current (DC) aircraft power distribution system. The electromagnetic circuit interrupter comprises a contact mechanism operable to separate first and second electrical contacts by a first predetermined distance d1 for a predetermined time ? so as to sustain an arc when the contact mechanism is opened. The contact mechanism is further operable to separate the first and second electrical contacts by a second predetermined distance d2 after the predetermined time ? so as to extinguish the arc. The first predetermined distance d1 is less than said second predetermined distance d2. By deliberately sustaining the arc for a relatively long period of time, this aspect of the present invention is particularly useful for extending the operational lifetime of the contacts and thereby of the electromagnetic circuit interrupter itself.

Abstract: A system for detecting the location of arc faults in an aircraft electrical wiring arrangement is provided. The system comprises a controller, operable to generate a test signal and a directional coupler for coupling the test signal into electrical wiring and for coupling reflected test signals from the electrical wiring to the controller. The electrical wiring comprises one or more wire under test and the controller is further operable to detect test signals reflected from arc faults in the wire under test and to analyse reflected test signals in order to determine one or more arc fault position therefrom. The wire under test may be live and testing can be performed without the need to use invasive in-line components.

Abstract: A switching circuit controls at least one semiconductor switch TR1 using drive signals generated from logic circuitry 4 that generates complementary drive signals on an upper and lower drive path. Validation circuitry is provided between the logic circuitry and the semiconductor switch that inhibits any uncontrolled switching of the semiconductor switch TR1 due to noise, such as lightning strike, appearing at the load.

Abstract: A switching circuit controls at least one semiconductor switch TR1 using drive signals generated from logic circuitry 4 that generates complementary drive signals on an upper and lower drive path. Validation circuitry is provided between the logic circuitry and the semiconductor switch that inhibits any uncontrolled switching of the semiconductor switch TR1 due to noise, such as lightning strike, appearing at the load.

Abstract: An approximate sinusoid is synthesised by subtracting the error between a periodic signal, for example a triangle wave, and a true sinusoid. The periodic signal is produced using a counter circuit, while the error signal is generated using a shift register circuit, both circuits being clocked by a common clock signal.

Abstract: A signal processor for a linear or rotary variable displacement transducer is provided in which input channels A and B are sequentially applied to a shared integrator such that any gain or offset errors introduced by the integrator are common to both channels and can be removed by subtraction or other signal processing actions.