Abstract: A system that implements a design process having a plurality of sub-processes each having a plurality of sub-steps. The system includes an independent application for implementing the design process. A series of independent sub-process applications each implements one sub-process of the design process. A communications path provides for communications between the design process and each of the sub-process applications. The communications path also provides for communications between each of said plurality of sub-processes. An application library containing a plurality of executable applications is accessible by the design process and sub-processes to access and execute the plurality of application tools.

Abstract: A system for supplementing existing safety devices in light circuits by real-time monitoring of current and voltage levels in light circuits to diagnose and pinpoint problems in the circuit, and to activate a safety disconnect in the event hazardous conditions are detected. The system includes a monitor device electrically coupled to a light circuit service panel. The monitor device includes a switching means complementary to an existing disconnect means operable to independently disconnect a light circuit from a power source, and input means for collecting real-time data from a plurality of circuits. The input means includes a means for detecting unequal current levels in the light circuits, a means for continuous surveillance of ground wire continuity for each light circuit, and means for continuous sensing of the current and voltage levels in each light circuit.

Abstract: A method of reconizing a fault current in a control unit and to a control unit having a circuit for recognizing the fault current. According to the invention, a current flowing into the control unit which could cause the control unit to be damaged or to operate incorrectly is detected and a fault signal is produced depending on the current detected, the fault signal causing the load or the current supply for the control unit to be switched off, for example.

Abstract: A power distribution system includes circuits each having an electronic circuit breaker as a protection for short-circuits and/or overloads, and a clocked power supply unit. The clocked power supply unit is connected to the circuits and feeds power to the circuits. The electronic circuit breaker has a power stage and an adjustable current limiting device connected to the power stage. The adjustable current limiting device, in the event of an overload, when a first adjustable current threshold is exceeded, turns off the power stage after a first adjustable disconnection time has expired, and in the event of a short circuit, after a second adjustable current threshold has been exceeded, turns off the power stage after a second disconnection time has expired.

Abstract: A failure detection scheme for switching voltage regulators senses a parameter which normally transitions above and below a predetermined threshold during each clock cycle. A decision circuit tracks the sensed parameter, and toggles an output when the sensed parameter transitions normally. A counter counts clock cycles, and toggles its output when a predetermined number is reached. The counter also has a reset input which receives the output of the decision circuit, and is reset to an initial value when the decision circuit output toggles. If the sensed parameter fails to transition normally, the reset input is not toggled and the count value increments with each clock cycle. If the failure persists for the predetermined number of clock cycles, the counter output toggles to indicate a failure, enabling the failed regulator to be repaired or replaced before additional failures occur.

Abstract: A configurable overload relay selectively operable in a single-phase mode of operation and a multi-phase mode of operation is configured to sense current flow through power conductors. The relay is further configured to determine a parameter related to the current flow, such as average current, vector sum of phase currents, and current imbalance, based on selection of either the single-phase or multi-phase mode of operation. Regardless of the selected mode of operation, the relay can provide protection for multiple types of power conductor fault conditions, including ground faults, overloads, and phase loss. The relay further can be configured to provide a reporting signal indicative of the value of the determined current-related parameter and/or the occurrence of the fault condition.

Abstract: A network protector includes a coil drive circuit for the trip actuator which operates as a current limiter to protect a trip coil with limited impedance at the upper limit of network voltage while assuring operation at network voltages of less than 10% rated voltage. A comparator provides gate drive current to a FET connected in series with the trip coil as long as coil current is below a reference voltage proportional to a specified maximum value of coil current. When the specified value of coil current is reached, the FET is latched off until the network protector is tripped open again.

Abstract: In a multiple break contact device for electrical switchgear the fixed contacts of the switching device are mounted in such a way that they can move linearly along an axis. The multiple break contact device has improved resistance to erosion.

Abstract: A multi processor computer system includes processors 102 in processor receptacles 104, and voltage modules 106 and voltage module receptacle 108. The system accepts both direct voltage processors powered directly from the system power plane, and regulated voltage processors which require a voltage regulator 300. The regulated voltage processors require the voltage regulator while the direct voltage processors cannot operate with a voltage regulator. Voltage module control circuit 110 tests and compares processor type signals from the processor receptacles and voltage module type signals from the voltage module receptacles, and produces a voltage validation signal which indicates the presence of a mismatch between any of the processors and its respective voltage module. The voltage validation signal modifies the conventional processor presence signal from the processor receptacles if a mismatch exists, preventing the system from being powered on.

Abstract: A differential protective relay and method for a microprocessor-based bus differential protective relay that ensures fast and sensitive operation under internal fault conditions and offers improved stability during external fault and other non-internal fault conditions. The method uses a two-slope differential characteristic to cope with small CT transformation errors without reducing relay sensitivity. The method can also use a saturation detector to switch dynamically between the 1-out-of-2 and 2-out-of-2 operating mode depending whether or not the CTs saturate. In a 2-out-of-2 operating mode, both the differential and directional elements must confirm a fault for the relay to trip. In a 1-out-of-2 mode, if saturation is not detected, the relay can trip without checking the fault direction.

Abstract: A method and system for controlling power to a cranking subsystem in a device having a power source is disclosed. The method and system comprise providing at least one switch and providing at least one controller. The switch is coupled with the power source and a portion of the device. The at least one controller is coupled with the switch. The at least one controller is for controlling the switch based detection of at least one failure in the portion of the device and to account for the at least one failure in a portion of the device. In one aspect, the method and system comprise monitoring a portion of the device and determining whether at least one failure exists in the portion of the device. In this aspect, the method and system also comprise utilizing the at least one controller to operate at least one switch in order to account for the at least one failure.

Abstract: A power supply supervisor having a line voltage detector is used to monitor a power supply. A peak detector detects the line voltage by measuring the PWM switching signal in the secondary of the transformer. A logic circuit couples to the peak detector and the under-voltage detector, etc. to generate a power good (PG) signal when the power supply outputs meet the specifications. The logic circuit outputs a FAIL signal to turn off the power supply when an abnormal situation, such as over-voltage, occurs. Furthermore, when AC power is lost or turned off, the logic circuit detects a low line voltage and generates a power-down-warning PG signal before the output voltages are disabled. When an abnormal situation occurs before the low line voltage is detected, the logic circuit latches the power supply in a power off state. If the abnormal situation occurs after the low line voltage is detected, the logic circuit turns off the power outputs, but disables the latch function.

Abstract: A circuit breaker which displays eletronically state of the circuit breaker and the cause of the disconnection which enables users to determine whether to reconnect a conductor which connects a source and a load in power distribution system. An arc display part is coupled to an arc fault detector, a ground display part is coupled to a ground fault detector and an overload display part is coupled to an overload detector. If arc fault occurs, the arc fault detector generates a trip signal and the trip signal is provided to the arc display part. As the trip signal from the arc fault detector is not provided to the ground display part and the overload display part, users can determine that arc fault has occurred by the lighting of the arc display part.

Abstract: In a protection circuit for a plurality of fans, an element is associated with each fan. The impedance or the current value of the element indicates the operation condition of the fan. For example, the impedance or the current value may be low if the fan is operative or functioning normally, and high when the fan is inoperative or functioning abnormally. The elements are arranged in parallel between two conductive lines. A detection circuit determines the total impedance or current value between the two lines. If the total impedance or current is not within a predetermined range which indicates that all fans are operating normally, at least one of the fans functions abnormally. The number of lines required to convey the operation status of the fans to the detection circuit is only two and does not depend on the number of fans involved.

Abstract: Current limiting using capacitor charge measurement to limit the supply current or load current of a circuit, or the current flowing through a device or switch, to prevent the time average current in the switch from exceeding a certain safe level. A replica circuit is used to provide a scaled version of the current in the main switch. The current output of the replica circuit is used to charge a capacitor during the first period of the clock signal so that the capacitor voltage, at any time during the on time, is proportional to the time integral of the current output of the replica circuit, and thus, the time integral of the current in the main circuit. The capacitor voltage, in turn, is compared with a known voltage to determine whether the charge that has flowed through the main switch has exceeded a predetermined maximum. The output of the comparator may be used in various ways, including as a control of the clock duty cycle to limit the on time of the main switch. Various embodiments are disclosed.

Abstract: A method and system for checking continuity of a motor 104, motor drive, motor relay 110, dc relay 108 and interconnections 122a-c thereof for a power steering system 204. The method and system of the invention produce minimal torque on a motor shaft 426 of the power steering system 204. The position of the motor shaft 426 is located using a Hall effect current sensor 114, a resolver and the like, depending on the type of motor. Thereafter, it is determined which switches 106a-f of an inverter circuitry 100 to switch to produce a minimal torque on the motor shaft 426. The inverter circuit 100 converts dc voltage from a power source 102 to ac voltage required by the motor 104. Thereafter, the switches 106a-f that produce the minimal torque on the motor shaft 426 are switched and current flow is checked to determine the continuity of the circuitry. To produce minimal torque on the motor shaft 426, the complementary pair of switches 106a-f to the first pair is then switched.

Abstract: A vehicular power generator control apparatus includes a switching transistor, a voltage control circuit, a high rotation speed detecting circuit, a leakage detecting circuit and a maximum conduction rate restricting circuit. The leakage detecting circuit detects leakage current flowing to a P-terminal. When the leakage current is detected, a maximum conduction rate set by the maximum conduction rate restricting circuit is changed from a small value at low rotation speeds to a large value. Thereby, field current flowing in a field coil is increased, a large voltage is generated at stator coils and current flows to a rectifying circuit to thereby reduce the leakage current which flows to the P-terminal.

Abstract: A device for sensing motor current for over-current protection in an electric power tool. The tool includes an electric motor supplied with electrical power via a live cable and incorporates over-current protection including a tripping circuit with a current sensor associated with the live cable. The device includes a toroid of the sensor and two cable segments connected in parallel to a section of the live cable such that the motor current will be distributed among the cable segments and live cable section in respective proportions. The toroid extends around one cable segment for sensing the respective proportion of the motor current.

Abstract: A reclosing apparatus for the auxiliary systems of a plant, in particular a power station, has drive modules (81) for actuating electrical drives (23a, 23b, 33, 53a, 53b, 63, 73) of the auxiliary systems. Each drive module (81) of a reclosable drive (23a, 33, 53a, 63, 73) is assigned a reclosing module (82). When a voltage interruption occurs, the reclosing modules (82) switch the drives (23a, 33, 53a, 63, 73) by opening switches (22a, 32a, 52a, 62, 72). If the end of the voltage interruption is detected within a predetermined time, the reclosing modules (82) switch the drives (23a, 33, 53a, 63, 73) on again. Each busbar (2, 3, 5, 6, 7) which supplies a drive (23a, 33, 53a, 63, 73) provided with a reclosing module (82) is equipped with a microprocessor-controlled voltage monitoring device (21).

Abstract: A method of controlling a variable speed draft inducer motor and fan in a gas furnace. The method comprises the steps of: detecting a first fault driving the motor to a maximum operating range; detecting a second fault forcing the motor to operate towards a minimum operating range; and generating a fault signal if both faults are detected substantially simultaneously.

Abstract: A protection device for monitoring current in a power cable to an electrical device and for controlling a remotely located starter for the electrical device in response to a system controller. The device includes a transformer magnetically linked with the power cable to produce a voltage signal in response to the presence of a changing current within the power cable. An input circuit located in a single housing together with the transformer is electrically connected to the transformer so as to receive the voltage signal. The input circuit produces, in response to the voltage signal, either a first signal or a first circuit condition at the output terminal of the input circuit, representative of the changing current in the power cable. A switch circuit also in the same container with the transformer has a terminal for sensing either a second signal or a second circuit condition of the remotely located system controller.

Abstract: A control apparatus for controlling multiple power loads in a vehicle includes a circuit for detecting a current abnormality of a power element and a circuit for monitoring a temperature abnormality in a locality of the power element. Circuits are also provided continuing or shutting down the power element based on information concerning the above stated current and/or temperature abnormalities, with a timing which is established according to a substantially constant period or a time interval which is stored in advance in a memory element.

Abstract: Current and voltage values (uk, ik) are measured for protection of an electrical power line (1). An adaptive estimator is used to analyze all the values within a measurement window, and to convert them to impedance values (Z). The line (1) is switched off if the impedance values (Z) assume unacceptable values. In order to shorten the reaction time, a warning signal (W) is produced if powerful radio-frequency signals are detected on the line (1). When the warning signal (W) occurs, the respective measurement window is located such that its start matches the time of the warning signal (W), and/or the respective measurement window is shortened.

Abstract: A control circuit of a switching state detecting device for a switch controls the value of a resistive element connected between one end of the switch (SW), of which the switching state is to be detected, and the power source or ground line, so the range of operating voltage can be widened, the current flowing at the time of switching on is suppressed so that power consumption of an electronic apparatus provided with the switching state detecting device for a switch is reduced, and improvement in detection precision can be made by causing the detection current to flow in a sure manner.

Abstract: A controller for a pulse width modulated electrical drive or a dual-mode, pulse width modulated/variable voltage inverter drive is coupled to sensors within a filter at the drive output. Upon detecting failure of the filter or filter components (e.g., a capacitor short or blown fuse) through the sensors, the controller either shuts down the drive or automatically switches the drive operating mode to an output mode which does not require filtering. Damage to the electrical system or downhole equipment from transmission of unfiltered or improperly filtered power may thus be averted upon failure of the filter or a filter component.

Abstract: A power control system, which serves to protect a dissipative/resistive load from exceeding a predetermined temperature limit. The power control system accurately models the temperature of the load and enforces a cooling period to reduce the temperature of the load being protected to a base temperature level if the predetermined temperature limit is reached. Also provided is a method of selectively connecting and disconnecting a resistive load to and from a power source to prevent the resistive load from exceeding a predetermined high temperature limit. The method includes sensing a voltage proportional to the instantaneous power passing through the resistive load by wiring a current sensing resistor in series with the resistive load. Then, a load temperature is modeled using a load temperature modeling circuit to produce an output voltage proportional to a present temperature of the resistive load.

Abstract: An arc fault detector, as a stand alone device or in combination with a circuit interrupting device such as a ground fault circuit interrupter (GFCI), protects from potentially dangerous arc fault conditions. The device utilizes line side and load side pickup coils to distinguish between arc faults occurring on the line or load side. An arc fault circuit interrupter (AFCI) circuitry portion of the device shares components from the GFCI circuitry portion, and utilizes the electromechanical power carrying portion of the GFCI, including AC line disconnect circuitry and a power supply. The AFCI employs quantitative detection using variable gain control in combination with either a load disconnect or audible/visual alarm indication. The device also includes a timer circuit, which permits the user to temporarily inhibit or disable the arc detection, and selective frequency filtering permitting arc detection in the presence of power line carrier communications.

Abstract: A low voltage cutoff circuit, a method of operating the same and a battery backup system incorporating the low voltage cutoff circuit or the method. In one embodiment, the low voltage cutoff circuit includes: (1) a low voltage monitor coupled between an input and an output of the low voltage cutoff circuit, (2) a cutoff switch, coupled between the input and the output and controlled by the low voltage monitor, that closes to couple the input to the output, the cutoff switch subject to failing closed when a voltage of the input is below a threshold and a load couplable to the output contains a short circuit and (3) a short circuit protection circuit, coupled to the low voltage monitor, that senses when the load contains the short circuit and directs the low voltage monitor to prevent the cutoff switch from closing.

Abstract: A method for starting up an electromagnetic actuator operating an engine cylinder valve. The actuator has two spaced electromagnets, between which an armature, connected to the cylinder valve, is reciprocated against a restoring spring from a center position to lie against a magnet pole face. An ECU alternatingly supplies the electromagnets with a capturing current, the level of which is regulated as a function of the approach of the armature toward a pole face, as detected by a sensor assembly. A reference temperature is detected for the magnets, and, at a normal temperature, the armature starts oscillating due to the alternating energization of the electromagnets, and is brought into contact with a pole face. Or, at a low temperature level, one of the electromagnets is supplied with a high current pulse.

Abstract: A ground fault relay, especially useful to detect motor leakage currents due to insulation failure. The invention operates in two (2) modes. The first mode is a “look-ahead” mode where possible motor circuit insulation failure is detected prior to the electrical motor being turned on, and the second mode is “real time” mode which detects leakage currents after the motor is turned on and during running of the motor. Processing circuitry is disclosed which enables a user to set predetermined values of leakage current to be detected and to trip the relay after comparison of the leakage current and the predetermined value, if the former is larger than the latter. This invention is able to accurately detect extremely small values of ground leakage current without experiencing nuisance tripping due to extraneous noise.

Abstract: The protecting apparatus includes a circuit for automatically and continuously determining the difference voltage between the voltage at the input side of a connecting circuit breaker and the voltage at an output side thereof between an electric generator and an associated power system, following initiation of closure of the connecting circuit breaker. The difference voltage is representative of the voltage angle of the generator relative to the electrical system. The difference voltage is compared against a reference value, which is selected such that a voltage angle value greater than the reference value will result in damage to the generator and/or the electrical system. An output signal is developed which can then be used to trip circuit breakers serving the electrical system if the reference value is exceeded by the difference voltage.

Abstract: A residual current device includes a residual current tripping circuit for actuating a release, and an additional monitoring device for checking the release, in which case a device is provided for electrically decoupling the residual current tripping circuit from the monitoring device.

Abstract: A battery module including at least one cell, at least one sensor, an interrupter device such as a fuse connected in series with the cells and an electronic switch. The electronic switch includes power transistors for short circuiting the series-connected components and the fuse if the sensor senses a malfunction and a diode for assuring that the power transistors maintain the series-connected circuit short circuited regardless of the subsequent status of the sensor. The diode memorizes the malfunction so that the module continues to conduct after the fuse blows, even if the sensors no longer detect any malfunction.

Abstract: Output protection for arc discharge lamp ballasts is provided by applying sampled ballast current to a burden capacitor selected to present a low impedance across the winding to a substantially symmetrical waveform of the sample current. Asymmetry between the positive and negative half-cycles of the sample waveform, such as partial rectification caused by abnormal lamp operation, results in charge buildup across the capacitor. Sufficient charge buildup actuates a ballast disabling switch such as a silicon controlled rectifier.

Abstract: This invention relates to an arrangement for sensing a change in pressure from a first state to a second state. This is function in a grid system which has a fault undetected by flow measurement devices. This arrangement consisting of remote monitors powered by a communication system with a stand alone power supply which will sense a significant change in pressure. The monitors, with time delay built in, transmit this change in status to a central host computer for grid system analysis. In normal means for stabilizing the grid system, a remote signal is sent from the host computer to an isolation device for isolating the fault from the remainder of the network system. Subsequently, the host computer notifies the operating department with written notice of the isolation action.

Abstract: A unique system has been provided to precisely locate the exact position of a short along a conductor, even if the conductor is co-located with other conductors, even conductors connected to low resistance loads. A combination of low frequency test pulse signals, at low duty cycles, and the use of a directional sensor made with shields, account for accuracy and reliability of the system. The shields are arranged to optimally shield and direct signals at the transmitter test signal frequency. The shields also acts to place the shorted wire an optimal distance from the sensor. A method of short circuit location, using the direction sensor of the above-mentioned detection system, is also provided.

Abstract: The present invention relates to a fail-safe timing circuit and on-delay circuit which does not produce an erroneous output where the delay time is shortened, due to a fault. The timing circuit comprises: an oscillation circuit (11) which produces a timing output from a cathode terminal of a PUT after a predetermined time lapse from input of an input signal (VIN); and a monitoring circuit (12) for monitoring for the normalcy of the oscillation circuit (11). Moreover the on-delay circuit comprises a self hold circuit (13) with an output signal (Vo) generated from the monitoring circuit (12) only when the normalcy of the oscillation circuit (11) is verified by generation of a falling signal of a cathode terminal voltage of the oscillation circuit (11), input to a second terminal (b), and the input signal (VIN) input to a first terminal (a), which produces an output signal only when the two input signals are both at a higher level than a power source potential.

Abstract: The method relates to discriminating between an internal arc and a circuit-breaking arc established in the enclosure of a circuit breaker in a bay of a medium or high voltage metal-clad substation. The appearance of an internal arc is detected by a protection system which responds by transmitting a disengagement order to the circuit breaker, thereby causing a circuit-breaking arc to appear. The pressure of the dielectric gas inside the enclosure of the circuit breaker, is continuously measured and recorded so that after the instant at which the disengagement order is transmitted, it is possible to recover a first pressure value measured before the instant. The first pressure value is then compared with a second pressure value measured after the said instant in order to identify whether the internal arc was struck in the circuit breaker enclosure.

Abstract: Arcing faults in electric power systems, such as switchgear, are detected by gathering light from components in the system and splitting the gathered light into two beams. The first beam is passed through a first narrow band filter to extract a wavelength characteristic of arcing in the material of the selected component, such as the copper in the switchgear conductors. The second beam is passed through a second filter having a narrow bandwidth, not including the characteristic wavelength. The extracted light signals are converted to a sensed light electrical signal and a background light electrical signal, respectively, by photodiodes and compared. If the sensed light electrical signal exceeds the background light electrical signal by a selected threshold, an output device such as a trip solenoid is actuated.

Abstract: A multiphase circuit interrupter includes a plurality of power phase sections for establishing and interrupting electrical power carrying paths for a plurality of phases Each power phase section includes first and second conductive regions which contact one another to complete the current carrying path for the phase. The second conductive region is movable to an interrupted position to interrupt the path. An interphase current carrying path is established between the power phase sections to conduct electrical energy between the sections following a trip event in any one of the sections. The interphase current carrying path may be established by a conductive element extending between the power phase sections. Channels may be formed in the interrupter housing between the power phase sections to communicate conductive plasma generated during separation of the contact regions from one another between the power phase sections.

Abstract: A method for detecting fault in a resolver generating a sine voltage and a cosine voltage. The method includes obtaining a sum of a square of the sine voltage and a square of the cosine voltage. The sum is filtered through a first filter having a first time constant to generate a first filter output. The sum is also filtered through a second filter having a second time constant to generate a second filter output. The first filter output and second filter output are compared to detect a fault in the resolver.

Abstract: A method of controlling a refrigerator including a power supply unit, an inverter applying three-phase power to a compressor is disclosed. The compressor is driven initially for a predetermined period of time. If the RPM of the compressor is not within the range between a maximum and a minimum RPM, a controller determines a malfunction of the compressor or a disconnection between the inverter and compressor during the predetermined period of time. The controller increases the number of the malfunction by one whenever the malfunction is determined. If the increased number is greater than a given number, the controller stops the compressor and alerts user to the malfunction.

Abstract: A device for limiting an alternating electric current includes a least one passive semiconductor configuration and a protection circuit. The semiconductor configuration is configured such that when a forward voltage is applied thereto, a forward current flows through the semiconductor configuration. The forward current increases monotonously with the forward voltage up to a saturation current at an associated saturation voltage. At a forward voltage above the saturation voltage, the forward current is limited to a limiting current that is smaller than the saturation current. The semiconductor configuration is further configured such that when a reverse voltage is applied, a reverse current flows through the passive semiconductor configuration.

Abstract: A compressor control device for a refrigerator and a method thereof sense a momentary power failure by comparing a set revolutions per minute with an operation revolutions per minute, and control an on/off operation of the compressor according to a compressor driving state after a power comeback or during a power failure duration when occurring a momentary power failure, thereby protecting the compressor. The compressor control device includes: a revolutions per minute sensor for sensing an operation revolutions per minute of the compressor; and a controller which determines a momentary power failure by comparing the operation revolutions per minute sensed by the revolutions per minute sensor with a set revolutions per minute, and controls an on/off operation of the compressor according to a compressor driving state after a power comeback or during a power failure duration when occurring a momentary power failure.

Abstract: An electronic module comprising a power supply conductor coupled to one or more electromechanical actuators to supply operable power to the electromechanical actuators. The electronic module also includes a moisture sensor positioned to sense moisture intrusion into the module. Further, the electronic module comprises a first transistor responsively coupled to the moisture sensor, the first transistor coupled to draw current from the power supply conductor when the first transistor is in a conductive state. In addition, the electronic module includes a second transistor responsively coupled to the first transistor and in turn controllingly coupled to the first transistor.

Abstract: A portable partial discharge detecting device for measuring partial discharge in energized electrical systems encloses a relay circuit and a DC power source. A pair of sensor circuits are enclosed within electrically coupling clamping mechanisms and are coupled to the relay circuit at sensor inputs by cabling. The clamping mechanisms engage the ground leads of the electrical system. Trip and alarm networks of the relay circuit continuously compare the picocoulomb values of the partial discharge pulses against user set threshold values. Relays coupled to the trip and alarm networks respond if the threshold values are exceeded. The alarm setting is always set to a pick-up value equal to or less than the trip setting. The trip network relays are coupled to a control circuit of the electrical system and can take the system off-line. The alarm network relays are coupled to an alarm circuit and can warn the user that a certain level of partial discharge has been reached within the electrical system.

Abstract: An electrical connector includes an insulative housing retaining signal and power contacts therein. A resettable power regulation device is attached to the housing and electrically connected to the power contact whereby an excessive-power condition caused by an excessive-current or excessive-voltage power signal transmitted through the power contact triggers a shut-down operation of the regulation device thereby terminating transmission of the power signal to protect an electrical device connected to the connector. The resettable power regulation device resumes transmission when the power condition decreases to an operational level.

Abstract: An overvoltage and transient protection circuit with extended bandwidth is provided for the protection of a low voltage test signal path (210) such as a test signal path in a multimeter. The disclosed circuit maintains the integrity of a test signal (TS) (114) transmitted by the test signal path (210) by minimizing the effect that unwanted capacitive coupling would otherwise have on the frequency transmission capability of the circuit. During normal operation of the circuit, a test signal path isolation circuit (218) is held between the test signal (TS) (114) and an equivalent buffered guard signal (GS) 227. Held between these equivalent values (TS=GS), no (or minimal) current will be generated in the components of the test signal path isolation circuit (218) as a result of parasitic capacitance. The guard signal (65) (227) is used with guard traces (412) and guard planes (414) to isolate other parts of the test signal path in much the same way.

Abstract: A power control (20, 40) for controlling the electric power fed from voltage source (12) to a load (13) comprises a field effect transistor (21, Q1) for either allowing or disabling the flow of current from voltage source to load as a response to the presence or absence of a control pulse led to the gate of the field effect transistor. Additionally the power control comprises means for measuring the change of the gate potential of the field effect transistor (24, R6, R7) and for either allowing or disabling a control pulse on the basis of the gate potential change measurement.

Abstract: A device load variation protection circuit connected to an output side of a device to protected the device from a variation in a load includes a detection circuit, a protection load, and a switch. The detection circuit detects the variation in the load. The protection load is connected to the output side of the device so as to be switchable between connection and disconnection. The switch switches between connection and disconnection of the protection load on the basis of a detection result from the detection circuit.