A ground fault interrupter circuit is arranged to protect a person from electrical shock due to a ground fault by operating a switching circuit in response to a signal proportional to a reduction in Q of a high frequency resonant circuit.

In a distribution circuit for connecting a load to an a-c source, it is known that a ground-to-neutral short tends to reduce the sensitivity of ground fault detectors that use a differential current transformer to sense line-to-ground leakage. A resonated coil on a core links the neutral conductor forming part of a protective device for interrupting the load circuit in the event of reduced Q of the resonated coil caused by a neutral-to-ground fault. The core must also link the line conductor, fo...

In a ground fault interrupter in which the relay switch for interrupting current through a-c lines has its actuating coil selectively connected by a controlled rectifier to receive a-c line power, a tendency towards relay switch chatter is suppressed by preventing the initiation of controlled rectifier conduction during the rapidly collapsing portions of the a-c power cycle.

A current monitoring and control circuit for use with a medical stimulation device for monitoring the exciting current to stimulation electrodes connected to the device is provided having a disabling component to inactivate a signal generating circuit resident within the stimulator. Operation of this disabling component may be controlled by the functioning of sampling and detection components preferably connected to the output of the signal generator and triggered by an undesirable output signal...

A combined fault and voltage indicator includes a rotatably-mounted target viewable from the exterior of the indicator for indicating the occurrence of a fault and a lamp viewable from the exterior of the indicator for indicating system operating voltage. The target is positioned in a reset-indicating state by a reset circuit which periodically energizes a first winding to position a permanent magnet mounted for rotation with the target. Upon occurrence of a fault circuitry within the indicator ...

An improved ground fault tester uses a magnetostrictive element or piezo-electric element, such as a multimorph, which changes dimensions upon being magnetized or electrically charged. The dimensional change is used to interrupt the power circuit in which the ground fault occurs. The existence of a ground fault is sensed by a sensor which supplies current to the magnetostrictive or piezo-electric element. In the case of the piezo-electric element, the charge is dissipated through a parallel disc...

A conventional residential ground fault circuit interrupting (GFCI) device is utilized to control a traditional circuit interrupter in protecting a large power distribution circuit against ground faults. The GFCI device is connected in an energization circuit for a solenoid operable to open the interrupter contacts. A sensor responds to ground faults on the distribution circuit by impressing the current signal on one side of the energization circuit, thus creating a current imbalance effective t...

The fault indicator case has a concave mounting surface along which extend two legs having at their ends mounted jaws with serrated surfaces for engaging cable from below. Camming surfaces on the jaws facilitate placing the case on the cable. A shield can be fastened to the case after having been mounted.

A visual, fault inspection and fault location system for millimeter waveguide and the like comprises a cylinder of optically transparent material having a lens system mounted at one end thereof and a conical reflector at the other to permit the viewing of internal waveguide wall faults at right angles to the optical axis of the lens system. A video transmitter includes a camera tube positioned to receive images relayed by the lens system. The described optics assembly can be mounted on a self-pr...

A thyristor fault-detecting apparatus comprises a thyristor bridge with A.C. terminals connected to a three-phase A.C. power supply and having six thyristor arms, and an inductive load connected to D.C. terminals of the bridge. Each of the A.C. paths has a saturable reactor with an output winding so set as to be excited by the line current within the range from .pi./3 to 2.pi./3 (rad). Output voltages of the reactors are rectified and added, so that a fault in the thyristor is detected by the di...