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: An electric power circuit with line voltage failure detection includes a pair of DC conductors for receiving a DC voltage, a capacitor connected across these conductors, and a main power converter connected to produce an output voltage on a main power bus in response to the DC voltage on the power conductors. A circuit branch connected across the power conductors includes the series connection of a primary winding of a transformer and a switching device. The switching device is operated to produce a series of voltage pulses across the secondary winding of the transformer. These voltage pulses are used to produce a second output voltage. The magnitude of these voltage pulses which occur during time when the switching device is off, is detected and a line failure indicating signal is produced when this magnitude falls below a predetermined value.

Abstract: An output stage with a protection circuit against negative overvoltage at its output terminal, having a transistor with collector output and with the emitter connected to a reference voltage line; a diode for protection against negative overvoltages present on the output is arranged between the collector and the output of the stage. In order to give the output of the stage a presettable minimum voltage level, the reference voltage line is set to a preset voltage which differs from the ground voltage. For this purpose, the circuit comprises an operational amplifier in a voltage-follower configuration, the output whereof is connected to the reference voltage line, a diode which is connected between the ground and the non-inverting terminal of the operational amplifier, and a current source which is connected between the non-inverting input of the operational amplifier and a negative supply line.

Abstract: In a circuit breaker having an instant time tripping test function, terminals which are connected to an electric power source of a control circuit of the circuit breaker and a quasi over-current signal generating circuit for tripping test are provided on a front face of a housing of the circuit breaker, and a widely usable detachable tripping tester comprising a D.C. power source and a switch is connected to the terminals, thereby a predetermined voltage is applied to the electric power circuit and the quasi over-current signal generating circuit for testing a tripping mechanism.

Abstract: A device and method for protecting D.C. powered electronic equipment to be isolated from a D.C. marine power source for minimizing the interference of extraneous signals on the power signals along with a back-up D.C. power source for powering the electronic equipment in the event of the loss of operative power signals from the D.C. source. The device may include a remote indicator for signalling the marine vessel operator that the electronic equipment is being powered from the back-up power source and not the main power source.

Abstract: Error-free, reliable registration of a fault in a power distribution circuit is achieved by a faulted circuit indicator that measures the current in the circuit after a discrete time delay following the detection of an overcurrent condition. A fault is registered only if the measured current is less than a prescribed level, evidencing that the overcurrent has operated a protection device (such as a fuse), upstream from the faulted circuit indicator, to interrupt the circuit and clear the fault. Hence, only actual (true) faults, resulting in circuit interruption and isolation of the fault, will be indicated, thereby precluding false registrations that may otherwise occur from non-faults such as transient currents, momentary overloads, inrush currents, and the like.

Abstract: An electronic circuit device having a protection circuit for protecting a switching system electronic circuit when a ground terminal is removed from the device. The protection circuit includes a detection circuit for detecting the ground terminal has been removed from ground as a change in an electronic potential of the ground terminal, an input cut-off circuit connected between an input terminal and the electronic circuit to control an operation of the electronic circuit, a low voltage protection circuit for controlling an operation of the electronic circuit in response to an output signal from the detection circuit, and a memory circuit for controlling an operation of the input cut-off circuit in response to both output signals from the detection circuit and the low voltage protection circuit.

Abstract: A brownout reset generator includes a presettable counter and a reset controller consisting of a plurality of logic gates coupled to receive a brownout signal representing a power brownout condition or power assertion (i.e. power-up) and a clock signal, and to generate a brownout reset in response to and of selectively longer duration than the brownout signal. Following the leading edge of the brownout signal (i.e. initiation of the brownout condition), the counter is preset to a selected value and remains preset for the duration of the brownout signal. Following the trailing edge of the brownout signal (i.e. termination of the brownout condition), the counter begins counting clock pulses. The counter outputs a timing pulse after a selected number of clock pulses representing a predetermined time interval have been counted.

Abstract: A low voltage monitor and microcontroller output monitoring circuit for insuring proper operation of a microcontroller in a furnace control system. A switch connected to a reset port of the microcontroller is capable of putting either a high or low voltage signal at the reset port. A high signal is required for normal operation of the microcontroller. The low voltage monitor connects to a power supply providing power to the microcontroller and causes the switch to provide a low signal to the reset port if the output voltage of the power supply drops below a predetermined level. The output monitoring circuit insures that the microcontroller is operating properly by insuring that the microcontroller is producing an output signal at a predetermined frequency and repetition rate. If the output signal is not at the predetermined frequency, the output monitoring circuit causes a low voltage to be present at the reset port.

Abstract: A power cut-off circuit comprises a voltage monitoring circuit and an over-ride circuit (25), the voltage monitoring circuit comparing a portion of the battery voltage with a fixed reference voltage by way of a comparator (26) which, upon change of state, de-enegizes a relay coil of a relay (14) and thereby disconnects the power to most of the vehicle, but not to the starter motor circuit (11), and the override circuit (25) monitors override inputs in response to override conditions, and re-energizes the relay coil in response to an override input, in turn restoring the previously disconnected power.

Abstract: An integrated circuit self-protected against a reversal of its supply battery polarity comprises a first DMOS power transistor connected with its source electrode side to an electric load to be driven toward ground, and a second, protective DMOS transistor which is connected with its source electrode side to a positive pole of the battery and with its drain electrode side to the drain electrode of the first transistor. The first and second transistors have in common the drain region formed on a single pod in the semiconductor substrate.

Abstract: An integrated circuit is shown in which provision is made for terminating or locking out the operating circuitry when the supply voltage has fallen below a level that can cause anomalous or unreliable operation. Certain selected transistors are provided with saturation sensors which operate to produce a current when the transistors go into collector saturation. When any of the sensors indicates the onset of saturation, clamping circuitry is energized to provide lock out. In addition, a temperature compensated dummy bandgap circuit is included to sense extremely low supply voltages and provide the lockout function under conditions where a reliable saturation indication might not be available.

Abstract: The protection device ocmprises automatic commutating means interposed between the base of a transistor to be protected and the collector of a power device to cause a flow of current having a low voltage drop between the base and the collector when the collector voltage falls below a predetermined value.

Abstract: A circuit is provided which responds to single or multiphase low or lost voltage situations and in the case of multiphase systems to phase reversals or shifts to disconnect a single or multiphase load from its source. A timing circuit is provided which prevents reactivation of the load until a prescribed time interval has elapsed. The reactivation may be either automatic or manual.

Abstract: An electromagnetically operated control system includes an actuator having an electromagnetic solenoid which exerts an electromagnetic force of the magnitude corresponding to the amount of electricity input to the solenoid, and a control circuit for controlling the amount of input electricity. The solenoid includes a pair of coils and the control circuit is changed over between a plurality of states including one state in which half of the amount of input electricity is applied to both coils, respectively, and another state in which upon a failure in either one of the coils the whole amount of input electricity is applied to the other coil. This control circuit assures a normal level of electromagnetic force, even upon a failure in one of the coils, with use of the normal one coil which is then applied with the whole of input electricity.

Abstract: This invention prevents a circuit breaker from being re-set for a time sufficient to insure safe dissipation of ionized gases. Current monitors and rectifiers generate a reduced voltage direct current output which is fed into an auxiliary rectifier circuit. That direct current output is proportional to current in power conductors controlled by a circuit breaker. A holding circuit has an electrical power source derived from the power conductors and connected to a release coil for the main power contacts in the circuit breaker. A holding relay has a holding coil in the rectifier circuit, and normally closed holding contacts in the holding circuit. A time switch is connected in shunt with the holding coil. When the direct current output reaches a value corresponding to an overcurrent condition in the power conductors, it energizes the holding coil to open the holding contacts and cause the release coil to trip open the main contacts. Concurrently, the time switch activates; after a predetermined time (e.g.

Abstract: There is disclosed a low voltage protection circuit for preventing overdischarging in a back-up battery. The circuit includes: switching a device which supplies voltage to the load and being connected in series between the battery and load; a charging device which charges the battery by being connected in parallel to the switching device; a first control device which determines the different operation-starting and operation-terminating voltage of the battery and, at the same time, controls the "on" and "off" of the switching device by being connected in parallel to the input terminal of the battery; and a second control device which generates hysteresis voltage between the operation-starting and operation-terminating voltage by supplying the voltage which determines the operation-terminating voltage to the first control device.

Abstract: A voltage drop detection circuit (1) able to detect a drop in an output voltage of a switching regulator which includes an error detection circuit for detecting a difference between the output voltage and a predetermined value and a feedback circuit (PC1, R1) for controlling a control circuit (2) of a switching transistor in response to an output signal from the error detection circuit (R2, R4, R5, IC1). The voltage drop detection circuit (1) is constructed to operate by using the output of the error detection circuit (R2, R4, R5, IC1) as a control input. When the output voltage becomes lower than the predetermined value, the current of a shunt regulator (IC1) is cut off, a transistor (Q2) is turned off, and a voltage drop is output from terminals (E1, E2).

Abstract: A driver circuit for driving from the same output node (6) an inductive relay (34) and a non-inductive lamp (30) having a transistor (16) for driving the relay and second transistor (18) for driving the lamp and a third transistor (90) having its current electrodes coupled between the control electrodes of the first and second transistors for sensing an inductively-induced voltage at the output node when the first transistor means is disabled to cease driving the relay and for enabling the first transistor in response thereto to dissipate the inductively-induced voltage at the output node so as to protect the second transistor. Alternative couplings of the third transistor to the second transistor are also disclosed.

Abstract: A protective device prevents electrical load, such as three-phase induction motor, from overheat fault caused by undervoltage and phase failure condition in a three-phase power supply system. The circuit arrangement of the protective device includes a rectifier circuit, a voltage dropping circuit, a filter circuit, a current limiting circuit, a photo coupling circuit, and a large current control switch for controlling actuating coil of an electromagnetic switch. When the fault condition of undervoltage and phase failure is happen, the protective device will cut the load off the three-phase power source so that both the load and electromagnetic can be protected.

Abstract: Low voltage inhibit control apparatus used in conjunction with a microprocessor system having a power supply, comprising a low voltage inhibit circuit providing a power down reset signal in response to the voltage dropping of the power supply, and control circuitry for preventing the power down reset signals from being supplied to the microprocessor system in response to receiving DATA and WRITE signals from the microprocessor.

Abstract: An apparatus for flicker protection when a servo motor driven sewing machine starts utilizing comparators. Setting the original voltage as the reference voltage and the dropped voltage as the monitor voltage, the comparator compares the voltages and, if the difference exceeded more than the predetermined value, signals for setting the maximum electric current to the servo motor are attenuated such that the voltage drop of the electric source will be reduced.

Abstract: A microcomputer based reclosing relay performs a number of sequences to generate a succession of reclosure signals for a circuit breaker at timed intervals. The digital processing unit of the relay maintains flags, counts and running times for generating the succession of timed reclosures in a volatile memory. Periodically, these flags, counts and running times are copied to a non-volatile memory such as an EEPROM. Upon restoration of power following an interruption of power which results in loss of the contents of the volatile memory, the digital processing unit recopies the flags, counts and running times saved in the non-volatile memory back into the volatile memory, so that the relay can resume generating the succession of reclosures from the point at which power was lost. The flags and counts are copied to the EEPROM only when they change state, while the running times are only saved once a second to prolong the service life of the EEPROM.

Abstract: A ground fault circuit interrupter is described which provides protection in the event of loss of neutral or ground, excess potential between neutral and ground and reversed input connections. Separate, independent tripping circuits are used for these latter faults and for ground faults, thus eliminating problems due to interfering signals and reducing reliance on any one component or group of components. An opto-emitter and opto-detector arrangement is used for detecting and causing tripping of a circuit breaker in the event of faults other than ground faults.

Abstract: An apparatus and method for delaying the reconnection of an electrical supply voltage to an electrical load when the supply voltage has been restored after an interruption. In its basic form, the apparatus comprises a circuit interrupter coupled between the network and the load for disconnecting the load from the network when the supply voltage has been interrupted and a sensing circuit coupled to the circuit interrupter and to the supply network for sensing when the supply voltage has been restored and for actuating the circuit interrupter to reconnect the supply and the load at a first predetermined time delay after the supply voltage has been restored. In additional embodiments, the apparatus prevents the disconnection of the network from the load during momentary interruptions of power for less than a specified amount of time, and a power saver circuit may be employed to conserve power, especially if electromechanical relays and power contactors are employed to realize parts of the apparatus.

Abstract: An automobile telephone device uses as its power source a battery for the automobile. This applies to an automobile telephone device with an automatic answering or receiving function. In the automobile telephone device, a voltage monitoring unit monitors the voltage of the battery. When the voltage falls near a limit voltage required for starting the automobile engine, the monitoring unit electrically interrupts a power source line connecting the battery and the telephone device via a proper switch circuit to thereby inhibit excessive consumption of the automobile battery by the automatic answering or receiving function during engine stoppage.

Abstract: A computer system having a power supply monitoring arrangement employs a number of comparators for detecting whether or not various supply voltages produced by the power supply for use in the computer are above or below a reference level, or whether an overcurrent condition exists. These detected conditions are used to determine whether or not the power supply should be shut down, or during power-up to determine whether the initialization routine can be started by the CPU. Delays are included to prevent an undervoltage condition from indicating shut down of the power supply during power-up.

Abstract: In a common drive output circuit for driving dissimilar switching semiconductor devices having different drive input characteristics by turning on and off dc power supplies to apply a voltage between the drive input terminals of either one of the switching semiconductor devices through two transistors connected in a Darlington pair, the collector circuit of one of the two transistors which is not at the output stage has a diode inserted in series which has such a polarity as to permit passage of the collector current.

Abstract: An undervoltage tripping unit for a power line circuit breaker features a holding solenoid and a boostig solenoid having their associated plungers coupled to move together so as to be retracted against the force of plunger biasing springs when both solenoids are energized. Release of the plungers from the retracted position is used to trip the associated power line circuit breaker when the line voltage falls below a tripping voltage level. The holding solenoid is continuously coupled to the circuit breaker power input terminals. The booster solenoid is energized through a plunger-actuated switch so as to be de-energized when the plungers are fully retracted or in a position proximate thereto.

Abstract: A three phase loss protection circuit for a three phase rectifier. The rectifier includes a circuit which inhibits its operation when either of two of the three phases are lost. In response to the loss of the third phase, the loss protection circuit causes one of the other two phases to be lost at the input to the inhibiting circuit. The loss protection circuit does not interfere with the operation of the inhibiting circuit when either of the two phases are lost. In an alternative embodiment, the loss protection circuit includes circuitry to ensure that the rectifier is inhibited even though part of a lost phase may be recreated by the rectifier's input filter.

Abstract: A current overload tripping device having a time-delayed leading tripping action during uneven loading of the phases of a multiphase circuit. The tripping device includes a current pickup for each phase wherein the current pickup members are connected in series with one another and with an electromagnetic converter. Each of the current pickup members comprises a winding surrounding a magnet yoke of an electromagnetic tripping device of each phase and the electromagnetic converter comprises a temperature/time-dependent device operating to provide a time-delayed tripping signal.

Abstract: An ESD protection circuit, suitable for use as part of an integrated circuit, limits the voltage potential at the contacts of the integrated circuit to a voltage potential difference range relative to, though extending beyond the voltage source potentials of the circuit protected. The ESD protection is effective regardless of whether the integrated circuit is powered. The ESD protection circuit includes a clamp subcircuit for limiting the voltage potential at a clamp point to a first voltage range approximately defined by the voltage source potentials and a voltage offset subcircuit, coupled between the clamp point and an integrated circuit contact, to establish a second voltage range encompassing the first voltage range. The voltage offset subcircuit conducts current between the clamp point and the contact to limit the voltage potential at the contact to the second voltage range.

Abstract: A protection circuit for a switched mode power supply has a reference voltage applied through a resistor to a first input terminal of a comparator. The second input terminal of the comparator is supplied with an indicating voltage that is a function of the magnitude of input current to the supply. A capacitor precludes rapid changes in the voltage applied to the second input terminal. When a trip level is reached, the comparator operates a latch for disabling the pulse width modulator of the supply. A diode is coupled between the high capacity voltage output of the supply and the first input terminal of the comparator for rapidly changing the voltage applied to the first input terminal to operate the latch, in response to a significant decrease in voltage at the high capacity output.

Abstract: An automatic switching apparatus is disclosed for a system employing a battery and a charging device. A load is automatically disconnected in response to the decrease in voltage caused by an inactivation of the charging device so that the battery will not be undesirably discharges if the load is not turned off. An override switch is provided to allow the load to draw power even when the charging device is not operating.

Abstract: When a voltage (V) of a D.C. power source having an internal resistance (5a) exceeds an "exciting voltage" (FIG. 2), transistors (21, 28 and 33) turn ON, and a transistor (30) turns OFF, and then a tripping winding 16 is excited to close a circuit breaker; on the other hand when the voltage (V) is lowered under a "tripping voltage", the transistor (33) turns OFF and the transistor (30) turns ON, and thereby a load resistor (31) which is less than a resistance 34 of the tripping winding 16 is connected to the D.C. power source; consequently, the voltage V is further lowered by the internal resistance (5a), and a voltage difference is produced between the exciting voltage and the tripping voltage, thus making a "hysteresis characteristic" between the exciting voltage and the tripping voltage.

Abstract: An integrated protection unit is a circuit breaker which includes basic overcurrent protection facility along with selective electrical accessories. A molded plastic accessory access cover secured to the integrated protection unit cover protects the accessory components contained within the integrated protection unit cover from the environment. A combined overcurrent trip actuator and multiple accessory unit is either field-installed or factory-installed within the integrated protection unit. One such actuator-accessory unit includes a fast release overcurrent trip circuit.

Abstract: A circuit breaker for the protection of electrical devices connected thereto provides immediate detection of power failure even if such failure occurs during the times of line voltage axis crossings. This is accomplished by providing and monitoring the amplitude of a synthesized waveform representing a full-wave rectified replica of the line voltage, combined with a 90.degree. phase-shifted full-wave rectified replica of the line voltage waveform. The composite waveform has a peak-to-peak excursion of approximately 20% about a DC average without nulls. The phase-shifted waveform replicas are produced by a phase shift network configured to provide a strong differentiating function, thereby causing the phase-shifted replicas to reflect virtually instantaneously failure of the power line voltage, and in particular failure in the vicinity of an axis crossing, by an immediate change in amplitude. Transient overvoltages and undervoltages are similarly reflected.

Abstract: A battery-operated standby power supply includes a circuit for the detection of failures in A.C. power line voltage provides immediate detection of power failure even if such failure occurs during the times of line voltage axis crossings. This is accomplished by providing and monitoring the amplitude of a synthesized waveform representing a full-wave rectified replica of the line voltage, combined with a 90.degree. phase-shifted full-wave rectified replica of the line voltage waveform. The composite waveform has a peak-to-peak excursion of approximately 20% about a DC average without nulls. The phase-shifted waveform replicas are produced by a phase shift network configured to provide a strong differentiating function, thereby causing the phase-shifted replicas to reflect virtually instantaneously failure of the power line voltage, and in particular failure in the vicinity of an axis crossing, by an immediate change in amplitude. Transient overvoltages and undervoltages are similarly reflected.

Abstract: Voltage monitor for monitoring the output voltage of a power source which can be connected to a power load, which includes a reference voltage source, comparators for comparing the power source voltage with the reference voltage, switches between the power source and the load, which can be controlled by an output from the comparators, such that the switches can be closed only when the power source voltages are within certain voltage limits and meet certain conditions, and also such that the load is disconnected when the power source voltages go beyond certain voltage or frequency limits. A timing circuit may also be provided for timing various voltage conditions.

Abstract: A system is disclosed for sequentially disconnecting multiple phases of a first power source (12) from an electrical load (14) requiring a minimum of interruption and connecting a second power source (28) to the electrical load. A first embodiment of the invention disconnects immediately the phase in which a trip condition requiring disconnection of the first source power is detected and disconnects phases of a first power source (12) in which a trip condition is not detected upon the detection of zero current flow in those phases. In a second embodiment of the invention, each of the phases of the first power source (12) is disconnected immediately from the electrical load (14) upon the detection of a trip condition in any one of the phases requiring disconnection of the first power source. In both embodiments of the invention, the phases of the second backup power source (28) are connected upon the detection of the occurrence of zero voltage points in the respective phases.

Abstract: An input protection structure effectively protects input circuitry from positive-going ESD pulses. The input protection structure includes a transistor having a reduced beta, connected in series with one or more diodes between the input pin and VCC. In one embodiment, the transistor having reduced beta is constructed in the same manner as a fuse device. The structure is formed in an integrated fashion, without the need for metallic interconnections within the structure itself, thereby decreasing impedance while minimizing surface area in the integrated surface.

Abstract: Output current of secondary winding of a current transformer (21) corresponding to current value of an A.C. power line (1) is led to series connection of an electric power circuit (500) and resistors (40,41); voltages obtained across the resistors (40,41) are input to a time delay circuit (70) which ignites a load break contact (200) in the A.C. power line (1) when an accident overcurrent flows in compliance with tripping characteristics. A quasi output signal or reference signal for testing of D.C. voltage is applied to the time delay circuit (70) when any current does not flow in the A.C. power line, thereby to enable tripping test of the circuit breaker as it is connected to the actual power line.

Abstract: A power cutoff circuit is added to the protector network disclosed in U.S. Pat. No. 4,675,772 so that when an interruption in power occurs, at least one suppressor remains connected to a load even though a source is disconnected from the load. In one embodiment, the power circuit includes a control circuit connected to the supply lines between an "upstream" suppressor and a filter portion of the network.

Abstract: A current sensing device comprises a constant d.c.

Abstract: An input protecting device of a semiconductor circuit device has a first power supply terminal (8) for providing a first supply potential, a second power supply terminal (9) for providing a second supply potential, a signal input terminal (1), a first clamping diode (3) provided between the first power supply terminal (8) and the signal input terminal (1) for clamping a voltage larger than the first supply potential applied to the signal input terminal (1), and a second clamping diode (4) provided between the second power supply terminal (9) and the signal input terminal (1) for clamping a voltage smaller than the second supply potential applied to the signal input terminal (1). A switching device (12, 20 or 33) selectively cuts off a current path between the first clamping diode (3) and the signal input terminal (1) when a voltage is not applied to the first power supply terminal (8).

Abstract: In a high voltage circuit interrupter (30) or recloser, an auxiliary undervoltage lockout mechanism (300) provides a backup lockout means to deenergize circuit contactor closing solenoid (78). Auxiliary undervoltage lockout device (300) provides a backup means to lock out recloser (30) after a period of time longer than the normal functioning time of the recloser to prevent damage to closing solenoid (78) in the event of low voltage or other unexpected conditions on the power line.

Abstract: Safety appparatus for sensing an electrically powered device connected to an AC power source to prevent the start-up of the device upon power restoration when the power device is in its "ON" operative condition includes a current sensing circuit that is responsive to reconnection of such a load to prevent the establishment of an electrical circuit path through the device. Included are circuits for sensing the presence of the AC power and for the generation of the sensing current are also presented.

Abstract: A power distribution system includes a plurality of power sources and load transfer units including transistors and diodes connected in series and leading to a common power output, each of the transistors being controller switchable subject to voltage levels of the respective input and output sides of said transistors, and the voltage and current level of said common power output. The system is part of an interconnection scheme in which all but one of the power sources is connected to a single load transfer unit, enabling the survival of at least a single power source with the failure of one of the load transfer units.

Abstract: An underload protection system for an electric motor connected to first and second power supply lines, the lines being connectable to an AC power supply. The system comprises a line voltage sensing circuit connected to the first line and having a line voltage signal impressed therein, and an amplitude adjustment circuit connected to the voltage sensing circuit for adjusting the line voltage signal to produce an amplitude adjusted voltage signal. A line current sensing circuit is connected to the second line and has a line current signal impressed thereon, and a phase adjustment circuit is connected to the current sensing circuit for adjusting the phase of the current signal to produce a phase adjusted current signal.