A system to detect arcing faults in an electrical distribution system with a line conductor connected to a utility power transformer. The system monitors the rate of change of electrical current in the line conductor and produces a signal which represents the rate of change. The system produces a pulse each time the rate-of-change signal exceeds a selected threshold, filters the rate-of-change signal and/or the pulses to substantially eliminate a signal or pulse which represents changes in the electrical current outside a selected frequency range, monitors the remaining pulses to detect when the number of pulses that occur within a selected time interval exceeds a predetermined threshold, and generates an arc-fault-detection signal in response to the occurrence of a number of pulses which exceed the threshold within the selected time interval.

Arcing fault detection system

A trip indicator for a circuit breaker in an electrical distribution system. The trip indicator provides a visual indication of the activation of a trip signal caused by arcing fault detector (AFD) or ground fault interrupter (GFI) circuitry. The trip indicator comprises one or more light sources, one or more plungers having a colored tip or one or more bimetal disk having a colored top. In response to activation of a trip signal by the AFD or GFI circuitry, the light source(s) illuminate, the plunger(s) move from a retracted position to an extended position and the bimetal disk(s) move from a generally flat position to a convex position. A conduit is provided within the housing of the protective device for conveying light or the reflection of light between the light source(s), plunger(s) or bimetal disk(s) and an opening of the housing. Where the circuit breaker includes both GFI and AFD circuitry, each generating a respective trip signal in response to the detection of a ground fault or arcing fault, the trip indicator is designed to indicate which of the respective fault conditions activated the trip signal.

Trip indicators for circuit protection devices

An arc fault detector system (10) detects arcing faults in an electrical distribution system by monitoring one or more conductors (14) and producing an input signal representing one or more electrical signal conditions in the circuit (12) to be monitored. This input signal is processed to develop signals representing the electrical current flow through the monitored circuit (12) and broadband noise signal components. The system (10) analyzes these signals to determine whether an arcing fault is present, and if so, outputs a trip signal which may be used directly or indirectly to trip a circuit breaker or other circuit interruption device (44).

Arc fault detection system

An actuating mechanism of a three-position switch, the switch comprising a main shaft supporting or actuating contacts and able to be moved selectively to three stable positions and a center crank which is pivotally mounted and can be actuated so as to take the three positions of the main shaft, the mechanism in addition having a mechanical system which produces a kinetic ratio between the angular movement of the center crank and that of the main shaft which increases when the center crank moves from the open position to the closed position, which results in the force transmitted to the electrical contacts increasing continuously as movement takes place from the open position to the closed position.

Three-position switch actuating mechanism

An improved ground source heat pump system wherein the subterranean piping installation comprises modular heat exchange units. Each modular heat exchange unit comprises a plurality of parallel secondary or branch conduits. The use of multiple parallel secondary conduits significantly increases the heat exchange capacity of the system. Because of the increased efficiency of such a system, less piping is required, which in turn reduces the cost of labor and materials to install such a system and the area of land mass required to contain it. Moreover, because the heat exchange units are modular, they can be prefabricated at a remote site and then conveniently transported to construction site and installed much more quickly than the extended lengths of conventional piping.

Ground source heat pump system comprising modular subterranean heat exchange units with multiple parallel secondary conduits

A combined current and voltage measuring apparatus for measuring voltage and current on a rod-shaped primary conductor for conducting current at an upper potential includes a cast resin body wherein there is embedded the sensor of a current measuring unit The case resin body is arranged in surrounding relation to the primary conductor and, in addition to carrying the sensor, it is also utilized as dielectric for the upper potential capacitor of a voltage divider which supplies the amplifier of a capacitive voltage measuring unit Embedded in the cast resin body is a cylindrical electrode which forms with the rod-shaped primary conductor extending through the electrode the capacitor on the high-voltage side of the capacitive voltage divider The sensor of the current measuring unit contains a winding without a ferrous core which surrounds the outside of the cylindrical electrode

Combined current and voltage measuring apparatus

For operating a heat pump installation with water as the refrigerant, a vacuum pump is employed as the compressor. If a liquid ring pump is used, its dissipation heat is fed into the heating loop. To this end, the heat output side of the heat exchanger associated with the loop of the sealing liquid is connected to the primary or secondary heat carrier loop of the heat consumer associated with the refrigerant loop.

Heat pump installation

The combined current and voltage measuring apparatus has a cast resin body which supports the current measuring unit. The voltage measuring unit includes a capacitive voltage divider with an amplifier connected thereto. The cast resin body is also utilized as dielectric for the capacitor on the high-voltage side of the capacitive voltage divider. Embedded in the cast resin body is an auxiliary capacitor with a dielectric which, with respect to temperature dependence, corresponds to the dielectric of the high-voltage capacitor. The auxiliary capacitor, in series with a resistor, is connected to an auxiliary generator. The voltage dropped across the resistor is supplied, after rectification, to an input of a differential amplifier; the other input of the differential amplifier is connected to the terminal away from ground of the capacitor on the low-voltage side of the capacitive voltage divider. With respect to the capacitors of the capacitive voltage divider, a warming of the capacitor on the high-voltage side different from the warming of the capacitor on the low-voltage side does not influence the measuring accuracy of the capacitive voltage measuring unit of the apparatus.

Temperature compensated combined current and voltage measuring apparatus

Kombinierte strom- und spannungsmesseinrichtung

The invention is directed to an actuator mechanism operating with the energy of a spring which snap actuates an electrical switching apparatus such as a vacuum switching apparatus. The actuator mechanism includes parts which are arranged movably independently of each other, namely, for the cocking motion of the spring and for the switching motion transmitted to the switching contacts of the switching apparatus. These parts cooperate in such a manner that the force of the spring, after being cocked, acts on the part associated with the switching motion automatically. The actuator mechanism is suited, for instance, as a manually operable, fast-acting drive for vacuum power circuit breakers.

Werner Kohler

Papers

Combined current and voltage measuring apparatus

Heat pump installation

Temperature compensated combined current and voltage measuring apparatus

Kombinierte strom- und spannungsmesseinrichtung

Actuating mechanism for snap-actuating an electric switching apparatus