Abstract: A method for controlling an inverter to improve the ability of the inverter to support power factor corrected (PFC) loads under transient conditions is provided. Changes in the load being provided power by an inverter may cause the RMS output voltage level of the inverter to drop. A PFC load may respond to such drops in the applied voltage level by increasing its current demand. This may cause the inverter current limit to be reached, forcing the inverter to be turned off, and causing the load to be dropped. This problem is avoided by responding to such load changes by immediately increasing the RMS output voltage level of the inverter to a level sufficient to minimize the voltage drop and prevent excessive current demands from the PFC load. The output voltage level of the inverter is then gradually reduced from the high voltage level to prevent the occurrence of oscillations due to interactions between the PFC load and the inverter controller.

Abstract: An apparatus to provide protection for electronic devices which receive power for their operation at least in part from a vehicle's electrical system and battery. The electronic device protecting apparatus has an electrical system voltage sensor, an engine start sensor, and an electronic device decoupler interconnected such that the electronic devices are decoupled from the electrical system and battery when the battery voltage drops below a predetermined level and when the engine is being started. The preferred apparatus allows the operator to select between a warning that system voltage is low and an automatic restart of the vehicle's engine and charging system. The apparatus further includes a bypass function to accommodate electronic devices which draw temporarily high current.

Abstract: An electric motor monitoring circuit apparatus for an electric motor has a three phase electric motor having an electric motor starter circuit. An insulation monitoring circuit is coupled to the electric motor and monitors insulation leakage of the electric motor and inhibits activation of the electric motor starter circuit when an insulation leakage exceeds a preselected threshold. A three phase monitor circuit is coupled to the electric motor for monitoring phase sequence in voltage amplitude for the electric motor.

Abstract: In an external cardiac defibrillator (8), a method and system for determining when a relay (22) has failed in a conductive state. The defibrillator (8) includes a charge circuit (14) that charges an energy storage capacitor (C) to a predetermined voltage. The relay (22) is closed to direct a defibrillation pulse from the energy storage capacitor to a patient (25) needing ventricular therapy. The relay (22) is then opened following application of the defibrillation pulse. A monitor circuit (18) monitors the voltage on the energy storage capacitor. If the measured voltage across the energy storage capacitor (C) is less than or equal to a threshold value after a predetermined delay, the relay (22) has failed. If the measured voltage exceeds the threshold value, the relay (22) is operating correctly.

Abstract: An under voltage trip device for low and medium voltage breakers, a first power supply receives unregulated power from a control voltage supply, which is rectified and regulated with portions of the power supply monitored by a processor. The output of the first power supply is supplied to a second power supply which allows pulsing modulating power to be supplied to a solenoid connected thereto. The current supplied to the solenoid is measured so as to represent the solenoid armature position which is measured and calculated by a processor and stored therein as well as being compared to stored values, thereby determining solenoid armature position and predicting or warning of solenoid failure. Connected to the second power supply is a third power supply which operates in a voltage regulator supply mode and a switcher mode during start-up and continuous running operation respectively, such mode being controlled by the processor.

Abstract: A control system used to monitor an AC power source connected to AC powered user equipment. The control system is designed to monitor the output voltages of the AC power source to ensure that they are maintained within a predetermined operating window consisting of a high voltage limit and a low voltage limit. If the voltages stray outside the operating window the control system activates a normally closed DC relay to disconnect the AC power source from the AC powered user equipment. The disconnection is immediate for voltages that stray above the high voltage limit and only occurs after a short delay for voltages below the low voltage limit. The control system also monitors the AC power source connection to the AC powered user equipment to ensure that no polarization errors exist in the connection.

Abstract: The present invention features a method and apparatus for detecting and enabling the clearance of high impedance faults (HIFs) in an electrical transmission or distribution system. Current in at least one phase in a distribution system is monitored in real time by sensors. Analog current signature information is then digitized for processing by a digital computer. Zero crossings are identified and current maxima and minima located. The first derivatives of the maxima and minima are computed and a modified Fast Fourier Transform (FFT) is then performed to convert time domain to frequency domain information. The transformed data is formatted and normalized and then applied to a trained neural network, which provides an output trigger signal when an HIF condition is probable. The trigger signal is made available to either a network administrator for manual intervention, or directly to switchgear to deactivate an affected portion of the network.

Abstract: An over discharge protection circuit for a rechargeable battery which prevents an over discharge of the battery in response to a current operating condition, even though the operational state of an electric/electronic apparatus is changed for the purpose of saving the power consumption. The over discharge protection circuit comprises a selector selecting a threshold voltage in response to the operating condition of the electric/electronic apparatus; a comparitor comparing the output terminal voltage of said battery with the threshold voltage selected by the selector; a switch opening or closing a power feed line along which the battery is powered; and a controller controlling the switch in response to the comparison result by the comparitor.

Abstract: An integrated-circuit (IC) chip formed with a D-to-A converter (DAC) and an amplifier to receive the DAC output and to produce a corresponding signal for an output terminal. The chip includes control circuitry to prevent harmful instability in the signal at the output terminal during times that one or more power supply voltages are changing. The control circuitry includes a voltage-monitoring device which produces a RESET signal when a monitored supply voltage is beyond its nominal operating range. The RESET signal de-activates the amplifier input and output circuits, and following a short time delay after the start of RESET, disables the amplifier by killing the amplifier bias currents. The chip is arranged to receive a RESET signal from external devices, and to produce a RESET signal for any other devices in the system.

Abstract: An automatic safety switch provides an automotive battery with protection against accidental discharge due to operator neglect. Such operator neglect includes inadvertent use of electrical circuits such as headlights, parking lights, or interior lights subsequently to turning the ignition off. This invention is connected in series with at least one of the power cables connecting the battery to the fuse box of a vehicle. The choice of power cable is made based on where the circuits to be protected are connected inside the fuse box itself. The automatic safety switch is connected as close to the fuse box as possible, since all necessary connection points are available in the immediate vicinity of the fuse box. The automatic safety switch comprises circuitry that impedes a current flow to its protected output loads when the battery voltage has diminished to a minimum voltage that can safely start a vehicle. The automatic safety switch remains in its current impeded state until reset by the ignition switch.

Abstract: An on-vehicle electronic controller which controls the operation of a device of an automobile or an internal combustion engine is disclosed. A relay intermittently supplies power to a controlled apparatus. The controller first causes the apparatus to be operated for a predetermined period of time while the relay is off, thus ensuring that any residual voltage at the relay terminal is discharged. After the predetermined time, the relay terminal voltage is compared to a predetermined voltage. If the voltage is greater than the predetermined voltage, it is determined that the relay is welded shut.

Abstract: A digital to analog converter (DAC) includes "shut-down" circuitry that opens connections between the DAC's reference and output sections. The shutdown circuitry provides reduced power consumption while permitting the DAC's control registers to retain their values. The invention is applicable to both stand-alone DAC and analog to digital converters (ADCs) which incorporate a DAC and can be microprocessor controlled.

Abstract: A circuit device connected between a driving circuit for an active control component such as an IGBT or MOSFET includes a capacitor which compensates for drops in the power supply voltage to the driving circuit and a voltage limiting cut-off device which cuts-off power to the driving circuit when the power supply voltage drop continues for a period long enough to cause a drop in voltage across the capacitor.

Abstract: A circuit configuration for undervoltage detection of a voltage source includes a reference voltage source being fed by the voltage source and having a first output, a second output, and a device for generating an enable signal at the second output only whenever a reference voltage has attained a stable value. A voltage divider divides a voltage furnished by the voltage source and supplies an output voltage. A comparator has a first input connected to the first output of the reference voltage source, a second input receiving the output voltage of the voltage divider, an output for supplying a detection signal, and a switching device being triggered by the enable signal for enabling the output of the comparator only after the enable signal has been generated.

Abstract: A device for preventing welding of the switch contacts of a heavy duty electromechanical relay comprises means (15, 16 and 17) adapted in use for monitoring the voltage supply to the relay coil (2) and detecting low voltage excursions therein. A counter (14) counts the number of low voltage excursions in the voltage supply to the relay coil (2) and an electronic switch (12) disconnects the voltage supply to the relay (2) if the number of low voltage excursions counted exceeds a predetermined number.

Abstract: An adjustable undervoltage trip fault interrupt circuit is used to prevent "nuisance" undervoltage fault trips caused by instantaneous sags in the AC power lines of less than a selectable time. The interrupt circuit includes a time delay circuit (IC4) responsive to a detected signal for generating a pulse signal having a selectable duration. A gating circuit (IC3) is responsive to the detected signal and the pulse signal for generating a fault trip signal only when the detected signal is longer than the selected duration of the pulse signal. In this manner, instantaneous line sags shorter than the selected duration of the pulse signal are eliminated from causing the "nuisance" interruption of a variable frequency drive controller.

Abstract: A power-on reset circuit (10) for resetting electronic circuitry to be monitored has been provided. The power-on reset circuit includes a trip point generator (12) including the worst case component (the component that requires the greatest power supply voltage to operate) within the electronic circuitry for setting the threshold voltage for taking the electronic circuitry out of reset such that if the worst case component is operative, it is guaranteed that all components are operative and, thus, the electronic circuitry can be taken out of reset. Moreover, because the threshold voltage is based upon the worst case component of the electronic circuitry, the threshold voltage of the trip point generator will adequately track the electronic circuitry over normal process and temperature variations.

Abstract: A circuit arrangement for controlling a load and for recognizing an interruption in a line to the load includes a measuring resistance connected in series with the load, a device for varying a resistance value of the measuring resistance as a function of a current passing through the load, and a diagnostic device for generating a diagnosis signal if a voltage drop, producible across the measuring resistance by a load current drops below a threshold value.

Abstract: An automatic power line monitor system is disclosed for use in monitoring the electrical voltage supplied to an electrical system or appliance by monitoring the supplied electrical voltage and preventing the supplied electrical voltage from reaching the electrical system or appliance when the supplied electrical voltage is not within a predetermined range and for automatically restoring the supplied electrical voltage to the electrical system or appliance when the supplied electrical voltage is within the predetermined range.

Abstract: An expert detection system includes a method and apparatus for detecting high impedance faults occurring on a distribution circuit coupled to an AC power source. Based upon an expert's knowledge of high impedance fault behavior and the performance of various fault detection techniques, the expert forms a belief as to whether a high impedance fault has indeed occurred. The expert's beliefs may be adjusted with an elliptic formula, and then used to weight the status output of each technique. The weighted multiple technique outputs are combined to determine whether a high impedance fault has occurred. The expert's beliefs are calibrated during initial start-up by comparison with a confirmed performance history of the detector using a scoring rule. The belief calibration may be included during operation to provide on-line adaption of the expert detector to the changing situations of the distribution circuit.

Abstract: An integrated circuit breaker is described having undervoltage trip capability along with automatic overcurrent protection. The undervoltage accessory further provides auxiliary power to the trip unit and allows the trip unit to report and record the undervoltage release operation.

Abstract: A circuit configuration for monitoring a supply voltage of a processor unit being clocked by an oscillator and requiring a minimum supply voltage, includes an undervoltage detector being connected to the processor unit. The undervoltage detector is in operation and generates a reset signal at a supply voltage being in a range between a lower first limit value and a higher second limit value and being below the minimum supply voltage. A comparator is connected to the processor unit. The comparator is in operation at a supply voltage above the second limit value and the comparator generates an activation signal at a supply voltage above a third limit value being above the minimum supply voltage. The oscillator is in operation at a supply voltage above the second limit value and the processor unit is in operation upon the appearance of the activation signal.

Abstract: The present invention features a method and apparatus for detecting and enabling the clearance of high impedance faults (HIFs) in an electrical transmission or distribution system. Current in at least one phase in a distribution system is monitored in real time by sensors. Analog current signature information is then digitized for processing by a digital computer. Zero crossings are identified and current maxima and minima located. The first derivatives of the maxima and minima are computed and a modified Fast Fourier Transform (FFT) is then performed to convert time domain to frequency domain information. The transformed data is formatted and normalized and then applied to a trained neural network, which provides an output trigger signal when an HIF condition is probable. The trigger signal is made available to either a network administrator for manual intervention, or directly to switchgear to deactivate an affected portion of the network.

Abstract: A simplified and economical power supply for redundant computer systems of control systems is disclosed. These control systems may include burner control for furnaces. The safety and reliability of the system are increased. The power supply comprises one single common voltage supply in the form of a self-monitoring power pack unit SN having a power pack NT, an undervoltage monitor UW and an overvoltage monitor. The self-monitoring power pack unit communicates with the redundant computer units P1, P2 via a supply line 1e. This single self-monitoring power pack unit is used according to the invention instead of the known fully parallel two-channel operation with two computer units and two power packs with appertaining components and supply lines. The overvoltage monitor UW and the undervoltage monitor UW are preferably checked for operability through the periodic transmission of a test signal.

Abstract: A disconnect switch circuit for disconnecting an under-voltage battery from a hard disk drive connected between a voltage supply line and ground includes a MOSFET device connected between the battery and the voltage supply line, control means responsive to the supply voltage on the voltage supply line for generating a control signal powering the gate of the MOSFET switch. The control signal turns on the MOSFET switch when the supply voltage is in normal condition and turns off the MOSFET switch when the supply voltage drops below an under-voltage limit, thereby beginning head retract in the hard disk drive.

Abstract: An electrical supply safety plug that prevents power from a mains electrical supply from being accessible to an electrical appliance unless the electrical supply safety plug is properly engaged with the socket outlets and the appliance is turned on. The electrical supply safety plug disconnects the electrical appliance in the event of current imbalance.

Abstract: A pulse motor control device comprises, as additional component parts, a power-off detecting circuit, and a turning-off circuit. The power-off detecting circuit detects, when a driving switch is turned off, a dropping of a voltage supplied to a driving circuit and outputs a power-off detection signal. The turning-off circuit includes diodes and a control resistor. The diodes are connected respectively to control terminals of all driving transistors of the driving circuit. When the control transistor is turned on in response to the power-off detection signal, voltages of control terminals of the driving transistors are dropped to the ground level through the diodes, thereby turning off the driving transistors.

Abstract: A circuit for protecting nonvolatile memories against loss of Vcc while Vpp is high. An NMOS gated by Vcc is connected, in series with a load element, between Vpp and ground. The node between the NMOS and the load element gates a PMOS which is interposed between Vpp and the memory. Thus when Vcc fails while Vpp is high, the NMOS will turn off, and the load element will pull up the gate of the PMOS to turn it off, interrupting the Vpp supply. This prevents spurious write or erase operations under these circumstances. The circuit can be designed to trigger at threshold voltages as low as V.sub.TN, and is thus particularly advantageous for operation with specified Vcc values of 3 Volts or less.

Abstract: An electrical supply safety socket that prevents power from a mains electrical supply to be accessible at the outlets of the socket unless an electrical appliance plug is properly engaged with the socket outlets and the appliance is turned on. The electrical supply safety socket is comprised of both a safety circuit and a safety socket which may act together to accomplish the above-described safety function. The safety circuit and the safety socket may also be used independently so as to provide similar safety functions.

Abstract: A protection system minimizing utilization equipment's exposure to, and power interruption resulting from, an under voltage condition in an electric power generating system includes generator current sensors, generator speed information, an exciter current sensor, voltage sensors, and a controller.

Abstract: An E-field sensing apparatus detects the energization of high voltage utility transmission and distribution lines. An external housing substantially shields internal components of the apparatus from the detected E-field. A conductive wire extends from the housing where it is exposed to the E-field. A signal is induced onto the exposed wire and sensed by the apparatus. The length of exposed wire and the distance of the apparatus from the high voltage line attenuate the E-field so the induced signal is within operational parameters of internal sensing components. Adjustments to the wire length and apparatus distance enable detection of E-fields surrounding power lines carrying voltage levels of a predetermined voltage level (i.e. approximately 2000 volts and higher). In response to the E-field the apparatus generates an analog output signal and a line isolation control (one-bit digital) signal. The analog output signal drives a meter, LED or other indicating device serving to aid maintenance engineers.

Abstract: A first switch element is connected in series with a rechargeable battery, a second switch element is connected in parallel to the series circuit of the rechargeable battery and the first switch element, and a control circuit controls ON and OFF states of the first switch element and the second switch element. The control circuit is so constructed as to turn OFF the first switch element to stop discharging and at the same time turn ON the second switch element when the battery voltage becomes lower than a predetermined value. The second switch element maintains the first switch element in OFF state even when the battery voltage of the rechargeable battery rises by self resetting of the rechargeable battery. When a charging voltage is applied to the rechargeable battery, the control circuit then turns ON the first switch element and turns OFF the second switch element.

Abstract: The electrical protection circuit disclosed comprises a latchup detection circuit, a threshold detector, an oscillator, a charge pump, a switching circuit, a voltage reference and detection circuit, and a signaling circuit. The latchup detection circuit, the threshold detector, the oscillator, the charge pump, and the switching circuit cooperate to provide latchup protection for the CMOS integrated circuit. The switching circuit provides integrated reverse current protection to the CMOS integrated circuit. The voltage reference and detection circuit, the threshold detector, and the signaling circuit provides low voltage protection for the SRAM-based software-downloaded Field Programmable Gate Array of the CMOS integrated circuit.

Abstract: A method and a device for recognizing defects in a triggering system of a controlled series compensator. An intervention is made in the closed-loop control of the controlled series compensator on the basis of an impedance differential (.DELTA.Z) determined from a setpoint impedance (Z.sub.S1, Z.sub.S2) and from an effective impedance (Z.sub.i) calculated from system variables (i.sub.L,u.sub.C), and in dependence upon the voltage level of a measured conduction current (i.sub.L). When the conduction currents (i.sub.L) are smaller than a limiting value (i.sub.LG), the firing is blocked in the branches, and when the conduction currents (i.sub.L) are greater than a limiting value (i.sub.LG), a firing-angle signal (S.sub..alpha.S) is generated, through which means the valve (Th1, Th2) can be protectively fired. Thus, one is able to recognize defects in the triggering system of the controlled series compensator by applying system variables (i.sub.L,u.sub.

Abstract: A device for protecting a power supply which is preferable for television receivers, etc. is disclosed. A diode is connected between a secondary anode of a power supply voltage feedback control photocoupler and a load of the power supply. When a voltage on the load is lowered due to an abnormality such as short-circuiting of the load, a control current for said power supply voltage feedback control photocoupler is caused to flow to the load via said diode to interrupt the control current for stopping the operation of the power supply. Overheating and/or breaking of components due to eddy current can be prevented on occurrence of an abnormality such as short-circuiting.

Abstract: A battery drain limitation circuit, for use in engine-powered vehicles and equipment that rely on a battery for starting the engine and for operating accessories, disconnects the battery from all loads when the battery voltage falls to a level below which the battery charge may be insufficient to start the engine. The circuit is rendered inoperable, when the engine is running, by means of a microphone that detects engine noise. The circuit includes a reset mechanism that reconnects the battery to all loads. The reset mechanism may be automatic or manually actuated. A timing circuit delays the disconnection for a period of time sufficient to start the engine. The drain limitation circuit employs a latching relay that, in its preferred embodiment, includes front and rear coils in tandem, axially separated by a collar with an internal detent. A front plunger and a rear plunger are disposed for axial movement within the coils and the collar.

Abstract: There is disclosed a monitoring apparatus for a multiphase electrical system of very simple and reliable circuit design capable of monitoring such a system and producing fault signals to operate protective relays and for visual indication. A main component of the apparatus is a multiphase, full-wave bridge rectifier circuit having matched voltage dropping input resistors so that the output of the bridge is a low voltage fluctuating DC signal such that neither the semiconductor diode rectifiers of the full-wave bridge or other internal components of the monitoring apparatus are exposed to high power line voltages. Phase unbalance in the apparatus is detected by evaluating the ratio of the peak to trough voltage of the fluctuating DC signal produced by the full-wave bridge.

Abstract: In a hand-held electronic apparatus, such as radio display pager, a control circuit is powered by a first battery to produce an control signal for operating an inductive device such as vibrator. A second battery is provided having an internal resistance lower than the internal resistance of the first battery. A capacitor is connected in parallel with the inductive device and the voltage developed thereacross is monitored by a voltage sensor, which produces a sensor output when the voltage exceeds a prescribed level. A first switching circuit is responsive to the control signal for coupling the inductive device to the second battery and responsive to the sensor output for decoupling it from the second battery. A second switching circuit also responds to the sensor output for coupling the inductive device to the first battery until the control signal ceases to exist.

Abstract: An undervoltage protection circuit, system and method is prodded for sending a reset signal to an electronic device during undervoltage time periods in which the device power supply voltage is less than a desired amount. The protection circuit includes a sensing circuit and a latching network adapted to quickly discharge a storage capacitor when the sensing circuit senses the undervoltages. A buffer network is included to send a reset signal to the electronic device whenever the storage capacitor discharges to a low latched level. The reset signal exists substantially throughout the undervoltage time period and also for a set delay period after the undervoltage time period ceases. During receipt of the reset signal, the electronic device will be inhibited from incurring damage or loss of data.

Abstract: A power source circuit consisting of a combination of a constant-voltage circuit (1) and a voltage raising/lowering circuit (2) which produces a plurality of output voltages by raising or lowering the output of the constant-voltage circuit. When a change in the power source voltage or the presence or absence of a heavy load is detected that information is supplied as a control mode signal to both the circuit (1) and circuit (2). For instance, when the power source voltage is reduced or when a heavy load is driven, the output voltage of the circuit (1) lowered and instead the rate of change in the output voltage of the circuit (2) is adjusted so that the output voltage may eventually become the same as in steady state.

Abstract: A battery charge monitor for automotive vehicles that includes electronic circuitry for connection to the vehicle battery and responsive to battery voltage to provide a first electrical signal when battery voltage decreases to a selected threshold level. A latching relay includes relay contacts for connection between the vehicle battery and vehicle battery loads, including the starter. A first relay coil is operatively coupled to the relay contacts and responsive to the first signal from the electronic circuitry to open the relay contacts and disconnect the battery from the battery loads including the starter. A second relay coil is operatively coupled to the relay contacts and responsive to a second electrical signal from an operator reset switch for reclosing the relay contacts and connecting the battery to the loads. Thus, when battery charge reaches a level below which starting may be difficult, the electronic circuitry cooperates with the latching relay to disconnect the battery from the loads.

Abstract: An arrangement for ensuring that a proper control level for a controlled unit is maintained when a supply voltage is removed from a control unit of a control system includes a switching circuit coupled between the control unit and the controlled unit. The controlled unit couples the control signal generated by the control unit to the controlled unit when the supply voltage is present and is responsive to the absence of the supply voltage for decoupling the output of the controlling unit from the input of the controlled unit. In this manner, a current path established by a protection circuit within the control unit when the supply voltage is removed is decoupled from the controlled unit and does not adversely affect the operation of the controlled unit.

Abstract: A vehicle storage battery protection system that senses a drop in battery voltage to a level at which the battery still retains sufficient power to start the vehicle. If the sensed voltage remains at or below this level for a time greater than the time normally required to start the vehicle, the battery is disconnected from the load and a hysteresis signal is provided to prevent a reconnection as the battery voltage begins to rise after the load has been disconnected. The load is automatically reconnected to the battery upon operation of the ignition switch to restart the vehicle. A reset circuit provides a small test voltage to the disconnected load, and senses a voltage drop caused by operation of the ignition switch to start the vehicle. This sensed voltage drop is detected and causes a main switch to reconnect the battery to the loads.

Abstract: A control apparatus for a vehicle equipped with an engine senses a condition indicating the capacity of the battery of the vehicle. When the capacity is below a prescribed level, the drive current to an actuator of the vehicle is adjusted to prevent the battery from becoming excessively discharged. In one form of the invention, the drive current is decreased to decrease the load on the battery. In another form of the invention, the actuator is controlled to increase the engine speed, thereby increasing the output of a generator driven by the engine. In another form of the invention, the actuator is controlled to stop the engine. When the engine is restarted, the initial rotational speed of the engine is high enough for the generator to recharge the battery.

Abstract: In a power unit, an output current supplied from the power unit to a load device is constantly detected as a load current. When the detected load current exceeds a predetermined current value, output power supplied from the power unit to the load device is reduced or cut off. An output voltage supplied from the power unit to the load device is constantly detected. When the detected output voltage has continued to be lower than a predetermined voltage value over a predetermined time period, the output power is reduced or cut off.

Abstract: A digital-to-analog converter for operating in a low power condition includes a delta-sigma modulator (10) for converting an n-bit digital input signal to an m-bit digital output signal. The output signal is filtered with a switched-capacitor filter (12) and an active RC low-pass filter (18). A low power supply detect circuit receives two power supply input voltages, the low and the high power supplies, and outputs a control signal on a line (38) indicating a low power supply condition. The digital-to-analog converter includes an output stage (26) with the analog output thereof being connected to an analog output terminal (30). A switch (28) is provided for connecting the output stage to the analog output terminal (30) in normal operating mode. In a low power mode, the low power detect circuit (20) generates a control signal on line (38) in response to the power supply voltage falling below a predetermined threshold.

Abstract: The problem of noise and undesirable oscillations on a DC bus (46) are minimized using a transient suppressor (50) in connection with a 270 volt DC power system (10). The power system (10) includes an excited generator (17) developing AC power rectified to power the DC bus (46) for connection to loads (36). The transient suppressor (50) comprises a resistor (52) and a switch (54) connecting the resistor (52) across the DC bus (46). A control (60) senses bus voltage and load current and controls the switch (54) in response thereto. Indeed, the switch (54) is controlled in one of two modes of operation. The first mode comprises voltage control in which the switch (54) is turned on with a single pulse to reduce over voltage conditions, without introducing EMI noise. The second mode comprises pulse width modulating the switch (54) under low current conditions to reduce low frequency oscillations on the DC bus (46).

Abstract: A device for detecting and isolating a downed conductor in a three-phase four-wire multi-grounded distribution system cooperates with a power supply protective device if the device has a breaking capacity less than the maximum prospective short-circuit current of the distribution line, and the device is installed at a lateral of the distribution line. The device comprises a current detecting device, a high-pass filter, a band-pass filter, two arcing ground fault current-detecting circuits, a first overcurrent-detecting circuit that delivers an output when the output current form the current detecting device exceeds a predetermined value, a second overcurrent-detecting circuit that detects an overcurrent exceeding the breaking capacity of the device which has a breaking capacity less than the maximum prospective short-circuit current of the distribution line, a no-voltage detecting circuit for sensing that the distribution line is not electrically charged, and a trip mechanism.

Abstract: An apparatus for fault detection and coupled between a power supply line and a circuit to be powered. When a fault develops in the circuit that causes voltage in the power supply lines to decrease, the power being provided is interrupted from the circuit. Once the fault is removed, power is automatically returned to the circuit.

Abstract: A power loss protection system for use in a system having a spinning momentum wheel and connected to a power bus. The inventive system (10) isolates a protected circuit from the power bus (11) in the event of a system power loss and converts and regulates power taken from the kinetic energy stored in the spinning momentum wheel to a voltage sufficient to maintain operation of the protected circuit. In a most general sense, the inventive system includes a power loss detector (21) for detecting a power loss in the system bus and providing a first signal in response thereto and a regulator (26) for regulating the voltage derived from the momentum wheel energy to the protected circuit in response to the first signal.