Abstract: An arrangement is provided to power and initiate the output of information sensed and/or stored by a device in a sealed environment having a viewing window. The device is powered and the output is initiated by the input of a light source to the device. When the output is initiated, the device provides a display representing the information. In a specific arrangement, the device scrolls to display the information on a sequential, repetitive basis while the light source is directed onto the device. In one specific embodiment, the device is powered by a solar cell or the like. In one specific application of the invention, the information represents the real-time primary voltage of components and circuitry within the switchgear. In another specific application of the invention, the device is located within a sealed switchgear enclosure and the information represents the faulted phase or phases of the power distribution circuit to which the switchgear is connected.

Abstract: Method and apparatus are provided responsive to the circuit parameters at one or more locations of an electrical power transmission and/or distribution network for detecting protective device operation. The detection of the protective device operation is utilized to locate faults and also to ascertain the status of protective devices. This information is useful in automated power systems for desirable isolation and sectionalizing of faults for optimum restoration of the network. A fault detection unit of the present invention is responsive to sensed circuit parameters and provides at least first and second outputs indicative of protective device operations that open the circuit. The first output is provided upon the occurrence of an overcurrent followed by the loss of a circuit parameter, such as voltage, for a specified time duration. In a preferred arrangement, the timing for a specified time duration is started when the overcurrent ends.

Abstract: An arrangement is provided for accurately sensing the source voltage of a high-impedance source while supplying a variable burden. A current-sensing element is connected in series with a load circuit across a high-impedance source. The load circuit includes a variable burden load. A shunt regulator is connected with the variable burden load and is arranged to operate so that the combination of the shunt regulator and the variable burden present a controlled, nearly constant burden to the high-impedance source. The source voltage of the high-impedance source is sensed via the voltage across the series current-sensing element. While the output voltage is directly proportional to the burden, the output current is essentially unaffected by small variations in the burden.

Abstract: An overcurrent protection device is provided for one or more phases of a circuit that generates a control signal dependent upon an adjustable trip level setting after a fault has occurred. The device includes a blocking level detector that blocks the generation of the control signal is the current in any of the phases exceeds either a first predetermined blocking level or the adjustable trip level setting. In a preferred arrangement, before control-signal generation, the device also requires that the current in at least one phase is below a predetermined load level.

Abstract: A detector for high-voltage, polyphase gear, having a fuse-switch combination in each phase and a switch operator, includes voltage sensors which provide first time-varying signals indicative of the magnitude and phase orientation of the phase-to-ground voltages on each phase within the gear at the load side of the fuses. The first signals are vectorially added to provide a second time-varying signal, the peak value of which varies as the magnitude and phase orientation of the phase-to-ground voltages of the phases. The second signal is compared to a reference; an error signal is generated when and as long as the phase-to-ground voltages vary beyond set limits. A timer responds to the error signal and provides a third signal a predetermined time after initiation of the error signal, but only if the error signal persists for such time. The third signal is used to cause the operator to open the switches.

Abstract: A "ready" indicator for high-voltage switchgear. The switchgear contains switches having normal positions (opened or closed) and switch operators therefor. The switch operators may include stored energy devices which may be charged or uncharged. The switch operators may be selectively coupled to or decoupled from their respective switches. The switchgear may include an automatic control device which, depending upon circuit conditions, causes operation of the switch operators to operate their respective switches to selected positions. Appropriate sensors detect the presence or absence of certain conditions. For example, the sensors may detect the ability or inability of the automatic control device to effect operation of the switch operators, the position of the switch operator or of the switches (open or closed), the charged or uncharged state of the stored energy devices in the switch operators, and whether or not the switch operators are properly coupled to their switches.

Abstract: A sensing device is connected to an intermediate tap point on each phase leg of a polyphase system such as a grounded wye-connected capacitor bank to detect faulted capacitor units and thereby control a switching device to isolate the capacitor bank. The intermediate tap point is selected in each phase leg such that the number of series units (such as parallel capacitor groups) above the tap point equals (or exceeds by one) the number of series units below the tap point. The outputs of these sensing devices are coupled through a calibration network to a summing amplifier which operates to add the three signals vectorily to produce on AC output signal that is filtered by a 60 Hz band pass filter to attenuate unwanted harmonics and noise which might introduce error into the measurement. Initial balance is achieved by adjusting the magnitude of each phase to ground signal to equalize those signals from each of the intermediate tap points.

Abstract: A compact voltage sensing device for connection to an alternating current high voltage circuit is imbedded within an organic polymeric insulator body that is formed to provide both mechanism support and "line to ground" insulation for a conductor or component connected thereto. The voltage sensing device comprises a capacitor and step-down transformer in series from the conductor to ground which provides a low voltage output which may be used to determine the magnitude of the voltage on the conductor, or as a source of control voltage for auxiliary apparatus. The insulator body may be made to be equal in height and have the same mounting configuration as a conventional insulator so that it can be substituted for a conventional insulator in a distribution system. The performance of the insulator body as insulation is not compromised by the presence of internal electrical components.