A method of detecting a fault in a power distribution system includes placing a signal on the system at a frequency F.sub.1 and then detecting a change in the signal due to a change in the impedence of the system as a result of a fault wherein the change is one of a change in phase, a change in signal tone, or a change in voltage level at the load. In one embodiment, band reject filters can be used to diminish the signal at the load or source. In another embodiment, the power source can be a periodic pulsed power source and the signal can be placed on the system during an idle phase of the periodic pulsed power.

A method of detecting a fault in a power distribution system includes placing a signal on the system at a frequency F.sub.1 and then detecting a change in the signal due to a change in the impedence of the system as a result of a fault wherein the change is one of a change in phase, a change in signal tone, or a change in voltage level at the load. In one embodiment, band reject filters can be used to diminish the signal at the load or source. In another embodiment, the power source can be a periodic pulsed power source and the signal can be placed on the system during an idle phase of the periodic pulsed power.

A sensor probe. The probe includes a central loop and a plurality of peripheral loops disposed peripherally relative to the central loop. To maximize far-field suppression, current flows in a first direction through the central loop and in a second direction through each one of the plurality of peripheral loops, the first direction opposite to the second direction, and current through the central loop equals current through the plurality of peripheral loops.

A sensor probe. The probe includes a central loop and a plurality of peripheral loops disposed peripherally relative to the central loop. To maximize far-field suppression, current flows in a first direction through the central loop and in a second direction through each one of the plurality of peripheral loops, the first direction opposite to the second direction, and current through the central loop equals current through the plurality of peripheral loops.

An apparatus for measuring velocities of projectiles launched from firearms is disclosed. The apparatus includes a stationary clamp arm and a movable clamp arm works in concert with the stationary clamp arm for clamping the apparatus to a firearm. A thumb screw is employed to secure the movable clamp arm and the stationary clamp arm to the firearm. A sensor module, which is integrated to the stationary clamp, includes a first and second sensor coils, a first magnet adjacent to the first sensor coil, and a second magnet adjacent to the second sensor coil.

An apparatus for measuring velocities of projectiles launched from firearms is disclosed. The apparatus includes a stationary clamp arm and a movable clamp arm works in concert with the stationary clamp arm for clamping the apparatus to a firearm. A thumb screw is employed to secure the movable clamp arm and the stationary clamp arm to the firearm. A sensor module, which is integrated to the stationary clamp, includes a first and second sensor coils, a first magnet adjacent to the first sensor coil, and a second magnet adjacent to the second sensor coil.

A defect inspection apparatus may include a sensor block, a measuring block, a controller and a storage. The Sensor block may include a plurality of sensors arranged in a zigzag pattern to induce an eddy current to the semiconductor die. The measuring block may be configured to apply an oscillation signal of a set frequency to the sensor block and to receive a change in the set frequency of the oscillation signal. The controller configured to determine whether or not the semiconductor die includes a defect based on the change in the set frequency of the oscillation signal. The storage configured to store the change in the set frequency of the oscillation signal caused by the eddy current in the semiconductor die and position information of the defect in the semiconductor die.

Provided is a short-circuit determining apparatus comprising: a sensor configured to detect a time change of a main current flowing between a first main terminal and a second main terminal of a switching device having a control terminal, the first main terminal and the second main terminal; an integration unit configured to integrate an output of the sensor; a polarity determining unit configured to determine a polarity of the output of the sensor; and a short-circuit determining unit configured to determine a short-circuit of the switching device, based on a comparison result of an output of the integration unit and a short-circuit determination reference value according to a determination result of the polarity.

Provided is a short-circuit determining apparatus comprising: a sensor configured to detect a time change of a main current flowing between a first main terminal and a second main terminal of a switching device having a control terminal, the first main terminal and the second main terminal; an integration unit configured to integrate an output of the sensor; a polarity determining unit configured to determine a polarity of the output of the sensor; and a short-circuit determining unit configured to determine a short-circuit of the switching device, based on a comparison result of an output of the integration unit and a short-circuit determination reference value according to a determination result of the polarity.

A sensor device for testing electrical connections using contactless fault detection is disclosed. The sensor device includes: a surface coil comprising a plurality of concentric loops disposed at a first region located away from the electrical connections. The concentric loops generate a first magnetic field passing through the electrical connections, and the first magnetic field is equivalent to that generated by a coaxial intermediate current loop adjacent to the electrical connections based on an excitation current in the surface coil. The sensor device further includes a sensor adapted to detect a second magnetic field at a second region located away from the electrical connections, wherein variations in the detected second magnetic field provide categories of performance of the electrical connections.