Abstract: A data acquisition system which utilizes a fixed frequency anti-aliasing filter and an analog-to-digital converter which operates at a fixed sample rate and a Fourier transform generator and a transform truncator and an inverse transform generator so as to provide sample data output at rates lower than the analog-to-digital converter sampling rate. By using multiple transform truncators and multiple inverse transform generators which simultaneously operate, multiple sample data outputs can be obtained which are free of aliasing phenomena.

Abstract: A device for overvoltage protection of rectifier/inverter bridges employing gate-controlled solid-state switches without zero diodes is disclosed. To protect at least the solid-state switches of the rectifier/inverter bridge against overvoltages, the device incorporates one or two overvoltage protector units which are activated when the voltage between at least two protection connections exceeds the voltage across a storage capacitor of the overvoltage protector unit. Thus, a controllable switch connected in parallel with the storage capacitors is turned on when the voltage between two protection connections exceeds an excitation value and is turned off when the voltage falls below the excitation value, controlled by a control unit of the protector unit.

Abstract: An overvoltage protector for protecting equipment, especially telephone equipment, against high voltage surges such as are caused by lightning in the vicinity of the equipment or the cables to which it is connected, comprises one or more overvoltage protectors (42,58) mounted upon one face of an insulating support (18). A generally planar contact member (62) mounted upon the support member has a ground contact member (90) to make contact with a ground electrode (114) in the equipment to be protected and with each overvoltage protector. A spacer (60) of fusible plastics material extending between the contact member (62) and an interconnection (26) to one terminal (42A) of the protector melts when a sustained fault occurs. As the spacer melts, it permits an electrical connection between the contact member and the line to which the overvoltage protector is connected, effectively short-circuiting the line to ground.

Abstract: A fail-safe device is provided for a thyristor where the thryistor has a body member with extending tip, ring and ground leads. The fail-safe device includes an electrically conductive spring member having first, second and third contact ends. The spring member is sized to be fitted over the thyristor body with the first contact end opposing the tip lead, the second contact end opposing the ring lead and the third contact end opposing the ground lead. A dielectric spacer is provided disposed to space the first and second contact ends from the tip and ring leads. The spacer means is formed from a material selected to deform under a force of the bias of the spring at an elevated temperature generated in response to the thyristor failing to ground the tip or ring leads during an overvoltage condition.

Abstract: An alarm circuit for a transient voltage suppression circuit for protection of equipment using alternating current power is shown and described. This device utilizes a pair of diodes having the same terminals (polarity) connected to a node to which a resistor provides an AC voltage. The diodes conduct during one half cycle in normal operation, and the node is at a virtual ground when both diodes conduct. When a fuse from one diode to ground opens, current no longer flows and the voltage at the node rises as the other diode conducts and applies a voltage to resistors and an alarm input.There is also disclosed a suppression circuit which provides for isolation of the ground from neutral in the event of failure of the varistor.

Abstract: A protective PTC device is heated by a heater PTC device or by a resistor to an elevated temperature greater than ambient but less than its switching temperature. The elevated temperature of the protective PTC device reduces its switching response time, and minimizes variations in such response time with variations in ambient temperature. The protective PTC device is connected in series with an electrical load to reduce current to a load when the protective PTC device is switched to its high-resistance state by a temperature increase resulting from overcurrent. The heater PTC device or the heater resistor may be in parallel or in series with the protective PTC device. The heater PTC device does not carry load current, but the heater resistor may be placed in series with the load and the protective PTC device so as to carry load current along with the protective PTC device.

Abstract: Electrical transient surge protection of electrical equipment downstream from a power source plus safeguarding of apparatus for providing such surge protection against failure at high currents or high temperature. Distributed-resistance fuse links facilitate operation of non-linear over-voltage means, such as varistors, in clipping transient voltage surges and shunting resulting currents to ground so as to protect watt-hour meters and downstream loads from electrical surges, and to safeguard such varistors from failure. Such apparatus may be located in such diverse places as a power line weatherhead, a watt-hour meter base, an adapter between a meter base and its normal mounting socket, or a utility panel having such a socket, or in a circuit-breaker panel downstream of the meter and upstream of metered loads.

Abstract: An internal pressure explosion-proof system by which an electric motor or the like is not rendered operative until after gas in an airtight vessel is replaced with certainty by protective gas. The internal pressure explosion-proof system includes a gas flow detector provided in an exhaust pipe for detecting an amount of protective gas exhausted from an airtight vessel in which an electric appliance which may produce a spark or fire is accommodated, and a controller for enabling operation of the electric appliance when a flow amount detected by the gas flow rate detector when protective gas is fed into the airtight vessel reaches a predetermined level and the internal pressure of the airtight vessel exceeds another predetermined level.

Abstract: A protection arrangement for coupling a two-wire line to a SLIC includes surge protecting triacs between each wire and ground, and normally closed contacts coupling the wires to the SLIC. The triacs are triggered via varistors coupled to the wires on the SLIC side of the contacts, which are opened in response to over-voltages on the line, as detected via a diode bridge and threshold circuit. The triacs are thereby not triggered during over-voltage conditions so that their power dissipation is reduced during such faults, whereas they respond rapidly to surge conditions which accordingly need not be handled by the contacts.

Abstract: An protection barrier provides voltage and current necessarily conveyed to hazardous, such as explosive, areas. The system includes a current sensing circuit which triggers a silicon control rectifier based crowbar circuit in the event over current is detected. This triggering, in turn, trips a relay severing the current path entirely. A reverse polarity circuit provides for immediate clamping of improperly bias connections in a similar crowbar arrangement, and also provides for tripping of the circuit breaker. Thermistors are also provided in current series in the event the circuit breaker fails to trip, or is forcibly bypassed. The circuit breaker additional provides a visual indicator when it is in the tripped position. The intrinsic barrier system is suitable to serving as a first stage protection to zener barrier modules as utilized in the prior art.

Abstract: The invention provides an A/D converter which comprises reference voltage generator means for generating a plurality of reference input voltages from a power supply, a comparator composed of switching means for inputting into the A/D converter an external analog input voltage and the reference input voltages and of an amplifier for amplifying the respective input voltages, and control means for controlling the reference voltage generator means and the comparator on the basis of an output from the comparator; the amplifier circuit of the comparator sharing its power supply with the reference voltage generator means.

Abstract: The invention is directed to power line filter and surge protection circuit components and the circuits in which they are used to form a protective device for electrical equipment. The circuit components comprise wafers or disks of material having desired electrical properties such as varistor or capacitive characteristics. The disks are provided with electrode patterns on surfaces thereof which coact with apertures formed therein so as to electrically connect the components to electrical conductors of a system easily and effectively. The electrode patterns act in conjunction with one another to form common electrodes with the material interposed therebetween. The electrode patterns are optimized in the circuit components such that balanced protection is achieved over all electrical conductors. The components also eliminate the use of leads such that operating characteristics are improved significantly.

Abstract: Electrical transient surge protection of electrical equipment downstream from a power source plus safeguarding of apparatus for providing such surge protection against failure at high currents or high temperature. Non-linear over-voltage means, such as varistors, function to clip transient voltage surges and to shunt resulting currents to ground so as to protect watt-hour meters and downstram loads from electrical surges. Adjacent arc-extinguishing components aid in safeguarding varistors or similar over-voltage means from potentially catastrophic destruction in the event of extreme over-heating from unusually frequent or prolonged surges. Such apparatus may be located in such diverse places as a power line weatherhead, a watt-hour meter base, an adapter between a meter base and its normal mounting socket, or a utility panel having such a socket, or in a circuit-breaker panel or even an electrical outlet receptacle downstream of the meter and upstream of metered electrical loads.

Abstract: A driver circuit (10), with a minimum number of interconnects between itself and a conventional output driver device (14), controls the normal on/off operation of the output driver device, and additionally senses various fault conditions within the output driver device. The driver circuit (10) also preferably shuts down the output driver device when the latter device begins to operate in a current limiting mode, and generates diagnostic signals which identify the type of fault condition that is sensed.

Abstract: An electrical device comprising a plurality of electrical assemblies formed as interchangeable modules, aligned in an end-to-end serial array and enclosed in a polymeric weathershed housing, the electrical assemblies being electrically and mechanically coupled together. Each electrical assembly in turn comprises a plurality of electrical components aligned in a row and in electrical connection with one another via their axially-directed ends and under an axially-directed compressive force via a nonconductive filament winding. The electrical components can be varistors, resistors, capacitors, and insulators or any combination thereof. In the case of varistors used to form a surge arrester, for example, voltage ratings can be enlarged merely by serially coupling a plurality of separately wrapped electrical components in the form of MOV blocks.

Abstract: The disclosed faulted current indicator ignores temporary overloads and transients by inhibiting any trip resulting from an overcurrent signal until a disabling circuit senses that a fuse or circuit breaker has reduced the line current to zero.

Abstract: An adjustable, conductive body strap utilizing a connector securing a strip of material held in a closed loop with a mechanical connector with the interior surface of the strip of material being electrically conductive. An electrical connector connects the conductive surface of the strip of material to a connection point to provide for external electrical ground connection. The mechanical connector secures one end of the strip of material in place. The mechanical connector adjustably secures the opposite end of the strip of material.

Abstract: An IC socket having internal MOV devices for protecting an integrated circuit from damage due to transient overvoltages.Each MOV device is coupled between a lead of the socket and a common metallic grounding strip contained within the IC socket. The grounding strip has an output lead which is brought through the socket for connection to a convenient system grounding point.

Abstract: Surge-protective varistors connected to shunt transient surges in electrical power lines to ground before damage to watt-hour meters or downstream loads. Conductive laminar members provide compact parallel circuit interconnection of varistors to increase the current-carrying capacity of protective apparatus containing them.

Abstract: A gate drive circuit for an insulated gate bipolar transistor initially drives the gate to a first voltage potential which causes the transistor to partially turn on. A sensor detects when the transistor saturates at which point the gate drive voltage is increased to increase the conductivity of the transistor and reduce its saturation voltage drop. If, however, a load coupled to the transistor is short circuited, the transistor will never reach saturation and will remain partially turned on at a point where it has increased short circuit current handling capability. In addition, once the transistor has been fully turned on, should a short circuit load condition occur, the transistor will drop out of saturation causing the drive circuit to reduce the gate voltage to increase the short circuit current handling capability of the transistor.