Abstract: A fault indicator for indicating the occurrence of a fault current in a monitored conductor includes an electrostatically-actuated indicator assembly. During normal operation a lightweight indicator flag rotatably mounted in and viewable from the exterior of the indicator housing is held in a reset-indicating position by electrostatic force resulting from an electric field existing between the flag and adjacent electrodes. Upon occurrence of a fault current in the monitored conductor the electric field is removed and the indicator flag, under the influence of a permanent magnet, is caused to rotate to a fault-indicating position. By avoiding the use of magnetic actuator windings and associated pole pieces the indicator assembly is easier and more economical to construct.

Abstract: An indicator for instantaneously indicating the presence of voltage on a monitored electrical conductor of an AC power distribution system utilizes a high impedance liquid crystal display component providing an "N" display in response to an applied signal. The "N" segment display electrode and associated backplane display electrode are capacitively coupled to the monitored conductor and system ground to provide an "N" display when voltage is present on the conductor.

Abstract: A voltage indicator for instantaneously indicating the voltage level on an electrical conductor within a connector component in an AC power distribution system includes a housing for engaging the body of the connector component. Within the housing, the display electrodes of a multi-segment high impedance liquid crystal display component are coupled to the monitored conductor through a capacitive voltage divider to provide an unambiguous bar graph type indication of the voltage level on the conductor.

Abstract: A fault indicator for indicating the occurrence of a fault current in a monitored electrical conductor of an AC power distribution system utilizes a liquid crystal display having independent "F" and "N" display elements. A rectifier circuit capacatively coupled to the conductor charges a first capacitor in the presence of voltage on the conductor. A second capacitor is connected to the first capacitor by a first reed switch in magnetic communication with the conductor. Upon occurrence of a fault current the reed switch closes and a portion of the charge on the first capacitor is transferred to the second capacitor, which is connected to the "F" display segment electrodes of the liquid crystal display to cause an "F" to be displayed. The fault indication can be reset either by the slow discharge of the second capacitor, or by discharging the second capacitor through a second reed switch manually actuated by a magnetic reset tool from outside the fault indicator housing.

Abstract: A fault indicator operable from an internal battery for indicating the occurrence of a fault current in a monitored electrical conductor of an AC power distribution system. Upon occurrence of a fault current a reed switch in magnetic communication with the monitored conductor momentarily closes to connect the internal battery to a capacitor, which is charged by the battery during the switch closure. The capacitor is connected to the display electrodes of a high impedance liquid crystal display, which displays an "F" to indicate fault occurrence. The fault indication may be reset either by the slow discharge of the capacitor, by discharging the capacitor through a second reed switch manually actuated by a magnetic reset tool from outside the fault indicator housing, or automatically upon restoration of power in the conductor.

Abstract: A circuit condition monitoring system for an electrical power distribution system includes a system connector component having an integrally molded test point socket within which a circuit module is received to provide fault current or voltage loss monitoring of a system conductor within the connector. The test point socket provides capacitive coupling to the monitored conductor without the use of a metallic test point, and a ground return to the electrically conductive outer sheath of the connector. An electrically conductive end cap may be provided to cover the projecting end of the module when the module is installed in the socket. Adapters installed on the other end of the module enable the module to be installed on prior metallic contact-type test points.

Abstract: An electromechanical pulse counter for counting applied current pulses includes a magnetizable disc-shaped armature mounted for rotation about a fixed axis. Magnetic stepping poles diametrically disposed adjacent the circumference of the armature are momentarily magnetized by a magentic winding upon application of each current pulse to establish diametrically opposed magnetic poles in the armature. Permanent indexing magnets diametrically disposed adjacent the circumference at an angular position relative to the stepping poles magnetically coact with the magnetic poles established in the armature following each current pulse to cause the armature to rotate to align the established magnetic poles with the poles of the indexing magnets. Each subsequent current pulse causes another pair of diametrically opposed magnetic poles to be established in the armature, and the armature to subsequently rotate to align the newly established magnetic poles with the indexing magnets.

Abstract: A reset coordinated fault indicator for indicating the occurrence of a fault current in a monitored conductor includes an electrically actuated indicator flag. A trip circuit within the fault indicator impulses the indicator flag from a normal reset-indicating state to a fault-indicating state following the occurrence of a fault current in the conductor. A reset circuit periodically impulses the indicator flag to the reset-indicating state upon restoration of power to the conductor. To preclude simultaneous actuation of the trip and reset circuits and consequent failure of the indicator flag to register a fault, the trip circuit, upon the occurrence of a fault, first actuates the reset circuit to render the reset circuit inoperative, and then actuates the indicator flag to provide a fault indication.

Abstract: A device for indicating a circuit condition such as the occurrence of a fault current in a high voltage conductor from which the indicator device is suspended includes a housing having at the upper end thereof a pair of outwardly projecting cable engagement members. The engagement members are formed of a resilient insulating material and each include an outwardly projecting base portion and an inwardly projecting end portion which engages and holds the cable against the rear wall of the housing. Operating power for the indicator device is derived from the potential gradient of the electric field surrounding the conductor by means of a metallic plate positioned within the housing adjacent the conductor, and a metallic ring and electrically conductive coating within the lower end of the housing.

Abstract: A circuit condition monitoring system for an electrical power distribution system includes a connector component having an integrally formed test point which provides fault current or voltage loss monitoring of a conductor within the connector. The connector includes an electrically conductive outer sheath layer. An annular channel formed on the surface of and extending through this layer receives the cylindrical end of a circuit monitoring module to form an electrically-isolated sheath portion which is capacitively coupled to the system conductor and to the module to function as a test point for providing operating power to the module. An electrically conductive end cap may be provided to cover the test point when a module is not installed.

Abstract: A fault indicator for indicating the occurrence of a fault current in a monitored conductor includes an electrically actuated indicator flag. Trip circuitry within the fault indicator conditions the indicator flag from a normal reset-indicating state to a fault-indicating state upon the occurrence of a fault current in the conductor. Improved high impedance trip inhibiting circuitry inhibits the trip function following a loss of voltage in the conductor whereby the fault indicator is rendered insensitive to inrush current during a period immediately following restoration of power to the system.

Abstract: A detector for indicating loss of voltage on a monitored conductor includes first and second serially connected capacitors, and a rectifier circuit which derives operating power from the monitored conductor to charge the capacitors in the presence of voltage on the conductor. A forward-biased diode connected across the second capacitor limits the voltage developed across the second capacitor during charging to a relatively low level. Upon loss of voltage a portion of the charge in the first capacitor is transferred to the second capacitor, causing the voltage across the second capacitor to reverse polarity and progressively increase. This causes an enhanced field effect transistor connected across the capacitor to become conductive and discharge the first capacitor through a relay or other indicating device to provide a control effect indicative of voltage loss.

Abstract: A detector for indicating the occurrence of a surge current in the ground return conductor of a lightning arrestor or other monitored conductor includes two clamps which establish electrical connection with the conductor at two spaced locations along its length. A rectifier circuit develops an actuator signal from the voltage induced between the two locations to activate an electromechanical counter or indicator flag. The clamps are installable on the conductor without access to the ends thereof to facilitate installation of the detector on an existing conductor.

Abstract: A fault indicator includes a status indicator for indicating normal and fault conditions on a monitored conductor. Trip circuitry within the fault indicator conditions the status indicator from a normal-indicating to a fault-indicating state upon the occurrence of a fault current in the conductor. Trip inhibit circuitry, including a loss of voltage sensor, inhibits the trip circuitry following a power failure whereby the fault indicator is rendered insensitive to inrush current during a period immediately following restoration of power to the system.

Abstract: A clamping mechanism for mounting a monitoring device to a electrical cable includes a pair of clamp members biased for engaging movement toward one another. A compression member between the clamp members ordinarily prevents engaging movement of the members. When pressed against a cable, the compression member deforms to allow the clamp members to move toward one another and encircle the cable and clamp the device thereon.

Abstract: A voltage monitoring system for mounting on a test point in an AC power distribution system provides an output when the voltage level on a conductor is above a predetermined minimum level. Within a sensing unit mounted on the test point a rectifier circuit develops from a capacitive coupling to the monitored conductor a voltage dependent on the voltage level of the conductor. A potentiometer applies a portion of the voltage to the gate of a MOSFET transistor, which actuates a reed-contact relay to control external switching circuitry. The potentiometer is user-adjustable from the front of the sensing unit to enable the minimum threshold level to be set.

Abstract: A sensor for monitoring loss of voltage on a monitored conductor includes first and second capacitors, each of which is charged by a rectifier circuit which derives operating power from the monitored conductor. Upon loss of voltage on the conductor, a discharge circuit discharges the first capacitor, while allowing the second capacitor to remain charged. When the voltage difference between the two capacitors exceeds a predetermined threshold level, an SCR discharge circuit discharges the second capacitor to provide an output signal.

Abstract: A fault indicator for indicating the occurrence of a fault current in an electrical conductor includes a rotatable indicator flag having fault-indicating and reset-indicating positions in response to applied magnetic fields. Upon occurrence of a fault current the indicator flag is set to the fault-indicating position by a first magnetic field generated by current flow through the conductor. Upon termination of the fault current the flag indicator is manually reset to the reset-indicating position by a permanent magnet, which is user-displaceable from a magnetically shielded position within the indicator housing to a position in magnetic communication with the flag indicator.

Abstract: A fault indicator for indicating the occurrence of a fault current in a power distribution system includes a rotatably mounted indicator flag. The indicator flag is actuated through successive 90.degree. trip and reset positions by a compact magnetic pole piece assembly having four radially extending magnetic pole segments which interact with four similarly aligned magnetic poles on the indicator flag. A pair of bidirectional windings on two of the pole segments magnetizes the pole segments to rotate the flag between successive trip and reset positions. Extensions on the two pole segments along the circumference of the indicator flag provide for positive rotation of the flag in a predetermined direction.

Abstract: A fault indicator for use in conjunction with components of a power distribution system contained within a protective enclosure includes a magnetic test point on the exterior surface of the enclosure for indicating the occurrence of a fault in associated circuits of the system. The fault indicator includes a circuit module mounted on a conventional test-point provided on one of the system components, and a magnetic indicator module mounted on the wall of the enclosure. The indicator module includes a magnetizable element which extends through the wall of the housing to provide a magnetic test point. Upon occurrence of a fault in the system, circuitry within the indicator module energizes a first winding in the indicator module to establish a magnetic state of a first polarity at the test point. Upon restoration of power, a reset circuit energizes a second winding to establish a magnetic state of opposite polarity at the test point.