Abstract: A microprocessor based overcurrent trip unit includes an analog circuit for monitoring phase currents in the electrical interrupting device. The analog circuit is adapted to interface with the microprocessor over a range of selectable setpoints for instantaneous tripping and at the same time accurately monitor the phase currents even during a condition when the current sensing transformers are saturated. The overcurrent trip unit also allows the function of the long time delay characteristics of protection curve to be varied in order to provide better coordination with the characteristics of other overcurrent tripping devices in an electrical distribution system, such as a current limiting fuse, thereby enhancing the overall reliability of the system. For example, the function may be varied to provide either a fixed or FLAT, It, I.sup.2 t and I.sup.4 t functions.

Abstract: A surge protector includes a housing having therein a wire wound resistor and a fuse separated by a partition wall. In one embodiment for use with high density information transmission, the resistor is of very low value and preferably is 5.6 ohms. The leads from the resistor and fuse are glued in position. The resistor wire is wound about a mandrel and is widely spaced to prevent arcing between adjacent coils of the resistor. A high temperature coating covers the resistor coils and mandrel effectively immobilizing the coils from movement in response to a magnetic field generated when high voltage is applied to the resistor. A cover closes the housing and conceals the components. The housing is empty of potting material.

Abstract: A power surge protection apparatus (10) protects circuitry from electrical surges induced in an alternating current power connection to the circuity. The apparatus (10) comprises first, second, and third stages (16, 17, 18), which serve to clamp and dissipate superfluous energy, such as that from a power surge, on the power connection (12a, 12b). The first stage (16) comprises a metal oxide varistor MOV 1 and a capacitor (C1) for helping to clamp and dissipate large-duration continuous surges on the power connection (12a, 12b). The second stage comprises an RC-LC filter with resistor R1, capacitor C2, inductor L1, and capacitor C3. Moreover, the second stage (17) has a metal oxide varistor MOV 2. Importantly, the second stage (17) further comprises a bifilar transformer T1 situated between the connections (24A, 24b).

Abstract: An electrical connector interface (10) provides for voltage surge protection. The connector interface (10) includes electrical interface conductors (12), an electrical ground conductor (14), and a selectively conductive material (18). The ground conductor (14) is spaced apart from the electrical interface conductors (12), and the selectively conductive material (18) is electrically coupled to the electrical interface conductors (12) and to the electrical ground conductor (14). The selectively conductive material (18) has low electrical conductivity within a predetermined voltage range, and has high electrical conductivity outside the predetermined voltage range.

Abstract: A 1-bit D/A conversion circuit according to the present invention comprises an RZ signal generating circuit and a PRZ signal generating circuit. The RZ signal generating circuit receives 1-bit digital data sampled at a predetermined frequency, converts the digital data into a first RZ signal and a second RZ signal complementary to the first RZ signal, shifts the first and second RZ signals with respect to each other by an integral multiple of the predetermined frequency, which is greater than one, and outputs these RZ signals. The PRZ signal generating circuit receives the first and second RZ signals, combines these signals together, and outputs a signal which is a type of a PRZ signal.

Abstract: An ESD protection circuit includes a portion for protecting a pair of power lines and a portion for protecting an I/O pin. The power line protection portion includes at least three SCRs electrically connected in series between the power lines. A zener diode is electrically connected between a gate of the SCR at one end of the series and the negative power line, and a resistor is electrically connected between the gate of the one SCR and the positive power line. The gates of the other SCRs in the series are electrically connected to the negative power line or to their own cathode. The I/O pin protection portion includes a plurality of SCRs connected in series between the power lines with the I/O pin being connected between the SCR at one end of the series and the next adjacent SCR in the series. A separate zener diode is electrically connected between the gate of the SCR at the one end of the series and the gate of the next adjacent SCR and the negative power line.

Abstract: A safety device for heated sensors. A signal representing a threshold voltage is compared with a signal from the sensor representing sensor temperature. If the latter is greater than the threshold signal, a switch is opened to remove power from the means for heating the sensor. The normal state of the switch is closed, so after cooling, heat is again applied to the sensor.

Abstract: A rotatable member is positioned coaxial with a joint between a first element and a second element. The joint defines an angle to be measured. The rotatable member has coded information thereon. First and second sensing heads are attached to respective elements. Coded information is arranged on the rotatable member so as to periodically pass in readable proximity to the sensing heads once every revolution of the rotatable member. A decoding system is provided for each sensing head. Each decoding system includes threshold circuitry, a state machine, and a pulse generator for providing a timing strobe. A first timer uses a timing strobe from the first sensing head for continuously determining the average elapsed time for one complete revolution of the rotatable member. A second timer uses timing strobes from the first and second sensing heads to continuously determine the average elapsed time for the coded information on the rotatable member to travel from the first sensing head to the second head.

Abstract: An analog-to-digital converter circuit is disclosed that is capable of converting both positive and negative analog input signals, and that is capable of operating as either an analog-to-digital converter or a digital-to-analog converter. The converter includes a modifying filter, a series of substantially identical converter stages, and a restoring filter. An original reference signal is provided, coupled to a resistor array to provide a stage reference signal to each converter stage that is equivalent to the value of the bit of an N-bit binary word corresponding to that stage. An incoming analog signal is modified to ensure that it is positive before applying it in parallel to the converter stages. Each converter stage compares the modified analog signal to the sum of its own reference signal and the value of all stage reference signals for prior converter stages where the digital output of the stage was a binary "1.

Abstract: Abnormal changes in the non-linear characteristics of electronic components are an indication of abnormal conditions such as impending component or system failure. To detect such abnormal changes in nonlinearity, an electronic circuit is subjected to a calibration signal including at least one frequency component. Nonlinearity in the electronic circuit causes distortion components to be generated from the calibration signal. Preferably the nonlinearity is characterized by compensation coefficients that digitally compensate the nonlinearity. The compensation coefficients are adjusted in a feedback loop in response to measured values of the distortion components, so that the distortion components are minimized. At the end of the adjustment process, the transfer function of the electronic circuit is specified by the compensation coefficients, which are stored in memory.

Abstract: An apparatus and method for detecting analog signals representing patterns of n-bit RLL-encoded data read from a data storage device. R integrators each integrate the analog signal over successive time periods consisting of a preselected number n of bit cycles, where n>1, weighted by a preselected set of n orthogonal signals that are staircase functions which vary each bit cycle to provide R integrated weighted outputs. The R integrated weighted outputs are converted by a lookup table or read-only memory into an n-bit digital representation corresponding to a unique one of the n-bit analog data patterns.

Abstract: Pulse signals indicating up or down of a time constant are received and counted. When a time-out occurs, a time constant change signal is output. At up counting, when input signal is low, the flip-flop 80 of each bit is forcibly set to 1. Then, an up counter consisting of the high-order two bits (control bits) is provided. A time constant of a variable integrator is changed in response to output of the high-order two bits, so that the time constant can be changed rapidly. On the other hand, if the input signal is high, a 5-bit down counter is provided. Thus, the time constant of the variable integrator can be changed gently.

Abstract: A surge arrester (1) for high voltage has a porcelain housing (2) with safety shields (3, 4, 7, 8). In the central area along the longitudinal axis of the surge arrester (1), safety shields (3) with a larger diameter may alternate with safety shields (4) having a smaller diameter. The surge arrester (1) has blow-out apertures (5) at its ends, and gas under high pressure flows out of these apertures in the event of a-short-circuit current. To protect the safety shields from damage, the safety shields (7, 8) that are closest to the blow-out apertures (5) are constructed with smaller diameters than the other safety shields.

Abstract: A method and apparatus for high speed decoding of a 20 bit wide data into 16-bit wide data in which the first ten bits and the lower ten bits are decoded simultaneously to ensure complete decoding and where the decoding of the second ten bits is dependent upon the running disparity of the first ten bits, the second ten bits are decoded twice, one assuming the decoded first ten bits will have a positive running disparity, and a second time assuming that the decoded first ten bits will have a negative running disparity.

Abstract: A sensor arrangement for producing a signal representative of currents having frequencies and/or characteristics associated with arcing within an alternating current electrical system. The arrangement is coupled to an appropriate arc monitoring circuit which determines if the signal produced by the sensor is the result of arcing within the electrical system. One embodiment of the sensor arrangement includes an inductor, and a capacitor connected in series with the primary winding of a transformer. The inductor is typically connected in series with a phase conductor of the electrical system, and the capacitor and the primary winding are connected to the phase conductor in parallel to the inductor. Another embodiment of the sensor arrangement includes a capacitor and the primary winding of a transformer connected in series between the phase conductor of the electrical system and either a ground or neutral conductor of the system.

Abstract: Variable-length encoded signals (e.g., those corresponding to video signals) are decoded using a lookup table whose indices are shorter than the longest possible variable-length encoded signal. N bits from the encoded bit stream are used as the index to retrieve from the lookup table a table entry, which comprises a flag bit indicating whether the variable-length encoded signal is a short code signal or a long code signal, one or more code-length bits, and one or more code-value bits. If the flag bit indicates that the variable-length encoded signal is a short code signal, then the decoded signal is generated using the code-value bits, wherein the code-length bits indicate the length of the variable-length encoded signal.

Abstract: A method for interrupting electrical power between two conductors is provided, including biasing an electrically conductive element into a conducting position between two contact regions of the conductors. The contact regions are preferably portions of arc runners coupled to the conductors. The conductors surround a magnetic core that generates an electromagnetic field due to current in the conductors. The conductive element is repelled to a non-conducting position by the electromagnetic field in response to an overcurrent condition in the conductors. A secondary response mechanism is moved in response to the overcurrent condition to maintain the conductive element in the non-conducting position. For more gradually occurring overcurrent conditions, the secondary response mechanism is attracted toward the core, displacing the conductive element to the non-conducting position.

Abstract: In order to provide an arrestor for a gas insulated switchgear in which the voltage share rates of respective zinc oxide non-linear resistance elements are made uniform, in an arrestor constituted by a plurality of columns for a gas insulated switchgear, the thickness or the capacitance of insulator spacers contacting the high voltage terminal or the ground terminal in respective columns is controlled, whereby the potentials of the zinc oxide non-linear resistance elements close to the high voltage terminal or to the ground terminal in the respective columns are shifted close to the potentials of the high voltage terminal or the ground terminal.

Abstract: A leakage protector comprising a lower and upper cover containing a control circuit which includes a bridge rectifier, a pulse absorber, a light-emitting diode, a comparator, a SCR and a relay wherein the output of the comparator causes the relay to interrupt power to a load.

Abstract: The present invention teaches a new and novel system for protecting people and property against electrical shock. The invention includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only, and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").