Abstract: Monitoring and control of analog electromechanical protective relays and digital mcroprocessor based relays is integrated through a system including slave stations which record and time tag contact activity at each of the analog relays. The slave stations continuously retain digital samples of a predetermined number of the most recent cycles of the currents and voltages at the analog relays and when a trip occurs store the retained samples as pre-fault values together with a preset number of post-fault samples. A master station communicates with the slave stations monitoring the analog relays and with the digital relays through a two way communications network. The master station repetitively polls the slave stations and digital relays for contact activity. Detailed data such as the time tags and pre-fault and post-fault currents and voltages are then requested from those stations reporting contact activity.

Abstract: There is disclosed herein a modular, high power, flyback transformer based power supply with step up and step down capability. The power supply uses multiple flyback transformers having switching transistors which may be either connected to one terminal of the primary winding or which may be placed in the center of the primary winding. The switching transistors are driven by pulse trains which are out of phase with each other. This results in lowered RMS values for ripple current through the input and output capacitors. The flyback voltage transients may be used to step up or step down the input voltage by varying the pulse width of the pulses in the switching pulse trains. In embodiments where the switching transistors are placed in the middle of the primary windings, better suppression of radio frequency emissions and current in safety ground wires is achieved.

Abstract: A code system for a device (30) that exhibits an input-output relationship characterized by an off-set and substantially linear performance (gain) comprising a resistor network (20) in cirucit with the device's coil (22), indicative of the device's GAIN and OFF-SET wherein the values of GAIN and OFF-SET are intrinsically coded within the value of a single resistor.

Abstract: An electrically conductive expulsion fuse manifold and bus for connecting and mounting a plurality of fuses which upon operation expel gases into the manifold is shown and described. The expulsion fuses are attached to the manifold by means of clamps, flanges, and/or threaded connections. Each expulsion fuse includes an expendable cap which may be blown off into the manifold under high magnitude capacitor discharge currents and/or fault currents for safe double-vented fuse operation. The manifold may also be non-conductive where electrical isolation is required and where a separate electrically conductive bus is employed.

Abstract: An automatic by-pass switch placed in the circuit on the secondary side of a transformer, one switch in series with each lamp of a series connected lighting circuit. The by-pass switching unit contains two normally closed, openable contacts and two strips of metal which serve as conductive current flow paths for the normally closed contacts. The two metal strips are placed in close spaced proximity to each other with air space therebetween so that the path of least resistance for the current flow is through the normally closed contacts and through the adjacent functioning lamp. If the functioning lamp burns out, the path of least resistance for the current flow becomes across the air space between the two metal strips. The electricity begins to arc across the metal strips. The heat generated by the arcing causes the metal strips to soften. Positioned on the backside of each metal strip is a compression spring applying pressure to bend the softened strips towards each other.

Abstract: A safety device adapted for use in a hand held tool for minimizing electrical shock to a user includes a ground plane disposed inside the electrical tool, which, should the tool become immersed in water or become unreasonaly wet, provides a path for electrical current, which energizes a solenoid which, in turn, interrupts the AC power supply. The safety device is preferably encased in a variety of module. The safety device contains a power supply, such as a battery and/or electret, that is independent of the AC power supply. Thus, the safety device can be tripped even if the tool is not turned on.

Abstract: A single-channel shunt-diode safety barrier for energizing a 2-wire transmitter, particularly for use in process control, incorporates within the barrier a floating d.c. power supply or its equivalent to enable the barrier to deliver into an earthed load a direct current substantially equal to that which it draws from the transmitter. The floating d.c. power supply is preferably derived from an external d.c. power source via a transformer or diode-pump circuit within the barrier itself. The barrier is enabled to pass superimposed digital or frequency signals in both directions to and from the transmitter.

Abstract: A digital circuit interrupter includes a microprocessor programmed for tailored overcurrent protection to industrial power systems containing a plurality of electric motors as well as motor protective relays. A communication link permits the overcurrent set points to be selectively set within the microprocessor memory from a remote location. The tailored overcurrent motor trip parameters are then derived by means of a logarithmic interpolation algorithm which resides in the microprocessor memory.

Abstract: An improved electrical appliance with short-circuit hazard protection includes a plug unit adapted to be connected to a source of electricity and a feed cord extending from the plug unit to the electrical appliance for supplying electric current thereto. The feed cord has a connector terminal by which the feed cord is rotatably or detachably coupled to the appliance. The appliance incorporates a first hazard sensor which detects an electrical hazard or short-circuit condition caused by moisture, water, or the like conductive medium. The plug units includes an interrupting circuit which disconnects the feed cord from the source of electricity in response to the detection of the hazard condition.

Abstract: An electric noise absorber, comprising divided magnetic substances made of ferrite, a holding member for holding the magnetic substances at its holding projections, and engaging members formed in the magnetic substances which engage with the holding projections. The electric noise absorber is attached to and detached from an electric cable easily without removing the electric cable and is composed of a minimum number of units.

Abstract: An electric noise absorber, comprising divided magnetic substances made of ferrite, a holding member made of elastic material and fixtures for being connected to each other or fixed to a component of an electronic device, and engaging grooves formed on the outer surfaces of the magnetic substances for engaging with the holding member, is attached to and detached from an electric cable easily without removing the electric cable, and is composed of a minimum number of units.

Abstract: A voltage transient protection circuit is provided for protecting a memory device such as a solid state memory cartridge from an undesired control signal which may occur during voltage transients in the primary supply voltage for such memory device. A transient detector detects transients occurring in the primary supply voltage. An isolation circuit is provided in the control bus, such isolation circuit being activated when a transient in the primary supply voltage is detected. A secondary voltage source supplies voltage to the transient detector and the isolation circuit sufficiently long while the primary voltage is fluctuating during a transient to permit the isolation circuit to isolate the control signal(s)el from said memory device.

Abstract: An input protection circuit for MOS devices includes a first resistor and a first parasitic bipolar transistor connected between an input pad and an input buffer circuit of a MOS device. The input protection circuit for MOS devices further includes a second resistor and a second parasitic bipolar transistor connected at a preceding stage of the input buffer circuit so that the gate oxide film of the input buffer circuit can be protected from being damaged by static charges or a voltage which is accidentally generated, without increasing the pattern size of the first parasitic bipolar transistor.

Abstract: A squaring circuit and an i.sup.2 t circuit utilizing the squaring circuit. The squaring circuit comprises a voltage-controlled oscillator and a frequency/current converter which are connected to one another, with the input voltage signal being supplied to the voltage-controlled oscillator and to the frequency/current converter on the one hand, and with the output voltage signal being tappable at an RC network connected to the output of the frequency/current converter on the other hand. The value of the output voltage is proportional to the square of the value of the input voltage. With this squaring circuit, it is possible to construct an i.sup.2 t protective circuit for protection of an electrical consumer from overload.

Abstract: A contact protective circuit for a relay detects a transient in the relay operating coil and turns on a low resistance power MOSFET in shunt relation with the contacts before the contacts close or open whereby arcing or deposition of metal on the contracts is avoided. Timing circuitry is provided for controlling the MOSFET to conduct large direct currents for short periods of time. In one embodiment, a ramp up circuit responds to a voltage level in a control signal to drive the operating coil and power a DC-to -DC converter and a timing circuit. The invention provides for hot side switching as well as cold side switching of a load.

Abstract: A microprocessor based circuit breaker has a removable rating plug which provides a reference for the current rating of the breaker. The removable rating plug also has an EEPROM to which the microcomputer of the circuit breaker writes for storage, the number of operations of the circuit breaker operating mechanism and a trip history of the breaker in the form of a count of the number of trips weighted by the magnitude of the trip current. The rating plug is periodically removed and plugged into a portable programmer which selectively displays the number of operations and operating history of the circuit breaker. The programmer clears this operating data when recorded and can write into the EEPROM the style and serial number of the circuit breaker with which the rating plug is to be used.

Abstract: A line protector for a communications circuit provides at least overvoltage protection. The overvoltage protection is effected through a solid state arrester such as a diode. As the solid state arrester is not as long as the carbon electrode type or gas tube arrester which it replaces, the line protector includes a conductive pedestal. The end of the pedestal adjacent to the solid state arrester is shaped to receive one electrode of the arrester, while the other end of the pedestal is shaped to provide a good contact to the grounding circuit of the protector.

Abstract: An anti-theft device that is adapted to be connected adjacent to or on a battery of a motor vehicle and including a power switch for disconnecting the battery from its standard battery cable when current flowing through the cable exceeds a preselected substantial amount of current associated with an attempt to start the vehicle. A lockout circuit is actuated by a remote transmitter for generating an external command signal to override the operation ofthe power switch. This device can be attached directly to a battery without external wiring and still provide the passive or self-arming anti-theft device.

Abstract: A guarded electronic circuit from reversal of its supply battery polarity comprises a MOS power transistor connected between one pole of the battery and ground, to drive an electric load to ground, and a second, protection MOS transistor connected between the pole and the first transistor; said transistors, which are both provided with respective inherent diodes between the source and the drain, have their related drain electrodes connected together. The resulting circuit is self-protected against possible reversal of the polarity of the battery to which it is connected, and can protect the electric load driven thereby.

Abstract: A contactor includes two DC sensors within the housing which are isolated from the tripping unit, from the power supply and from each other by the combination of a transformer and photoelectric coupling, the sensed signals being pulse width modulated and demodulated on the respective sides of the photoelectric coupling barrier.