Abstract: A method of detecting absence of connection of an external ground to a ground connection point associated with an AC supply circuit of a power supply. The AC supply circuit has hot and neutral conductors, with the neutral conductor externally connected to ground. The math involves (a) passing a current from the hot conductor to the neutral conductor via the ground connection point, (b) detecting passage of the current, (c) shutting down operation of the power supply upon detection of the current, and (d) bypassing at least an effective portion of the current from the ground connection point to external ground on connection of the ground connection point to external ground, thereby disabling the detection of passage of the current.

Abstract: A ground detector includes a detecting circuit formed of a polarity test circuit, a voltage dropping and rectifying circuit, a grounding test circuit and an alarm device, wherein the polarity test circuit leads in AC power supply and tests the polarity of its power wires so as to discriminate the standard zero potential circuit of the earth wire or neutral wire for grounding test reference; the voltage dropping and rectifying circuit converts lead-in AC power supply into DC power supply for working of the grounding test circuit; the grounding test circuit leads in the zero potential wire which is identified by the polarity test circuit, and compares its potential with the test circuit, so as to determine the grounding condition of the grounding bus, and to drive the alarm device when an error grounding of the rounding bus is detected, causing the alarm to output an audio alarm signal.

Abstract: The present invention teaches a new and novel system for protecting people and property against electrical shock. The invention includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only, and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking devices including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A ground fault circuit breaker includes separable contacts for interrupting current flow in a protected AC electric system when opened. The protected AC electric system includes a ground fault switch, such as a ground fault receptacle having a people protection ground fault trip curve, downstream from the ground fault circuit breaker. A current transformer generates an AC sensor signal representative of AC current flowing from the protected AC electric system to ground. A ground fault controller, connected to the current transformer, generates a ground fault trip signal as a function of the AC sensor signal and an equipment protection ground fault trip curve. A trip means, which is responsive to the ground fault trip signal, opens the separable contacts.

Abstract: In a circuit breaker, a power source current transformer (2) comprises: a secondary coil (6) arranged between two legs (1a and 1b) of a U-shaped part of a main circuit conductor (1), and an iron core (7) including an iron core leg (7a) which penetrates the secondary coil, and yokes (7b and 7b) which embrace the two legs (1a and 1b) of the U-shaped part of the main circuit conductor, the power source current transform supporting the current detecting means. As a result, the power source current transformer (2) is arranged compact inside the main circuit conductor (1), and the main circuit current, when flowing in each of the legs (1a and 1b) of the U-shaped part, produces the magnetic flux output acting on the secondary coil. Hence, even if the main circuit current is small, a great power source output can be obtained.

Abstract: Noise suppression system for a relay-switched windshield wiper, wherein reversal of current to a motor driving the wiper causes the motor to reverse. Filters contained within the motor, together with filters and shielding located external to the motor, suppress rf emissions.

Abstract: The present invention teaches a new and novel system for protecting people and property against electrical shock. The invention includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only, and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A three wire power supply circuit is provided comprising a circuit for monitoring the integrity of the ground connection of the power supply circuit. A circuit element is provided in the line-to-ground current path which conducts when current flows in the line-to-ground current path and is nonconductive when the ground connection is poor or absent. A microcontroller monitors the output of the circuit element and operates a buzzer or a light emitting diode to indicate when the ground connection is poor or absent.

Abstract: The present invention teaches a new and novel system for protecting people and property against electrical shock. The invention includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only, and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A new and novel system for protecting people and property against electrical shock. It includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only, and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A reverse wiring indicator for a GFCI receptacle alerts the installer in the event that the AC source has been improperly wired to the load or feedthrough terminals of the receptacle rather than to the source or input terminals. The reverse wiring indicator operates by open-circuiting one of the load or feedthrough terminals of the receptacle, and may take the form of a removable barrier which inhibits conduction through one of the power contact sets of the GFCI circuit breaker until the receptacle has been installed and successfully tested. The contact set through which conduction is inhibited is the one other than that to which the TEST switch is connected, and the other contact set is allowed to conduct in the normal manner.

Abstract: A ground fault interruption circuit has a detector circuit coupled to an electrical distribution circuit load to detect ground fault conditions in the load. A filtering circuit connected between the detector circuit and distribution network comprises a pi-network filter for attenuating common-mode electromagnetic interference and differential-mode electromagnetic interference. The pi-network filter includes three filter portions which together provide a third order filter to attenuate the interference signals at the frequencies of interest.

Abstract: Apparatus for providing an electrical system with protection against electrical shock in the event of a ground fault. The electrical system supplies power from a central mains inlet to at least one local electrical device. The central mains inlet includes a central ground fault detector and interrupter actuatable upon detection of a first predetermined level of current imbalance to interrupt the central mains inlet. A local ground fault detector is associated with the at least one local electrical device and is actuatable upon detecting a current imbalance of a second predetermined level which is lower than the first predetermined level. Controls are effective upon actuation of the local ground fault interrupter to actuate the central ground fault detector to cause it to interrupt the central mains inlet.

Abstract: A household electrical service (10) is protected against overheating by running a sensor line or wire (36 or 38), coextensively together with hot, neutral and ground lines or wires (12, 13, 14 or 31, 32, 33), from a power company hookup (50) to a main breaker switch (18), and from respective branch circuit breakers (19) throughout the branch circuits (21, 22). The sensor line or wire (36 or 38) may be a length of heat fusible or otherwise temperature variant material which has a load end connected to ground and a source end connected to a control circuit (51) which trips the breaker (18 or 19) when an overtemperature condition melts the wire. Protection is extended through to individual devices (43) by continuing the sensor wire through the device cord (42). For this purpose, a plug ground prong (46) and receptacle ground prong connection (45) provide isolated ground and sensor wire connections.

Abstract: A gas discharge device, such as a neon tube, is connected to a pair of output terminals of a power supply. The power supply has a transformer with a secondary winding that has first and second sub-windings. Each of the sub-winding is connected to a different output terminal and two conductors connect the first and second sub-windings to earth ground. A current sensor detects whether unequal magnitudes of current flow through in the two conductors. A resonant control circuit applies an excitation current to the primary winding of the transformer unless an imbalance of current flows. Thus excitation of the transformer is terminated when a high voltage ground fault occurs.

Abstract: An improved ground fault circuit interrupter (GFCI) device requires manual setting following initial connection to an AC power source or termination of a power source interruption. The improved GFCI device utilizes a controlled switching device which is responsive to a load power signal for allowing the relay contact sets of the GFCI device to be closed only when power is being made available at the output or load terminals. The controlled switching device preferably comprises an opto-isolator or other type of switching device which provides isolation between the GFCI input and output terminals when the relay contact sets are open. The improved GFCI device may be incorporated into portable units, such as plug-in or line cord units, for use with unprotected AC receptacles.

Abstract: A new and novel system for protecting people and property against electrical shock. It includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only, and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: The present invention teaches a new and novel system for protecting people and property against electrical shock. The invention includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only, and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A hospital bed electrical power module for powering external medical devices directly from the bed includes electrical isolation circuitry connected to prevent external device leakage current from traveling through the bed frame. The power module reduces the risk of shock to the patient due to the leakage current of the external device.

Abstract: A protective device for an externally powered electrical apparatus is disclosed. The protective device is designed to prevent accidental electrocution of the user if the power supply is subject to a short circuit. The protective device is an electromechanical device incorporating a device for detecting current differentials between non-ground electrical conductors, a normally closed switch in association with a fuse device, and a trigger circuit for terminating the current flow through the electrical apparatus when a short circuit is detected.

Abstract: A device and method for interrupting current flow to an electrically-powered apparatus is disclosed. The device includes a means for detecting a selected value of a physical parameter associated with the operation of the externally powered electrical apparatus, a trigger circuit incorporating an integrated circuit, a firing device which responds to the trigger circuit by generating a conductive plasma, an electronic measurement circuit to prevent unwanted firing of the firing device and thin conductors which are destroyed by the firing device when the conductive plasma forms an electric arc between them. Current flow to the electrically-powered apparatus is thereby terminated.

Abstract: A new and novel system for protecting people and property against electrical shock. It includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only, and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A ground fault interrupter circuit is disclosed, comprising a high-voltage input from a public utility transformer, polarity reversal means coupled to the high-voltage input with polarity-switchable output coupled through a thyristor to a relay means. Radio frequency (RF) detection means are coupled to the thyristor gate, causing the thyristor to energize the relay and interrupt load power when radio frequency interference is detected from the load. The RF detector means comprises a plurality of RF chokes and resistor-capacitor pairs feeding a rectifier diode coupled to the thyristor gate. When RF is detected, the diode feeds negative direct current to the thyristor gate, interrupting conduction of the thyristor and the LOAD.

Abstract: The present invention teaches a new and novel system for protecting people and property against electrical shock. The invention includes a number of preferred and other embodiments which have this as their goal, but which represent a number of distinctive and novel approaches to solving prior art problems. By way of example only and without limiting the scope of this invention, these approaches include novel immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A sensing conductor and a detection circuit cause a low resistance shorting of an appliance circuit in response to immersion in water or other electrically conductive liquid, and an interrupter device, preferably located in the plug of the cord set, reacts to overcurrent, by opening both sides of the line. The sensing conductor must be strategically placed, within the appliance housing, to pass in proximity to liquid access points and the current carrying parts of the appliance. The detection circuit may be within the appliance or in the plug, with the sensing conductor extended to the appliance as a third conductor in the line cord. When a small current passes between the sensing conductor and the ungrounded or grounded neutral sides of the line or earth ground, current is shunted through the detection circuit from the ungrounded to the grounded neutral conductor, and away from the appliance circuit.

Abstract: An appliance leakage current interrupter (ALCI) comprising a ground fault detecting circuit and a trip mechanism that is automatically actuated in response to the presence of a ground fault. Actuation of the trip mechanism automatically interrupts the flow of current to the appliance and permits movement of a reset button to take place to visually signal that current to the appliance has been interrupted, although interruption of current flow is not in any way dependent on movement of the reset button, whereupon if movement of the reset button is prevented for any reason, flow of current to the appliance is still automatically and instantaneously interrupted in response to the presence of a ground fault. A test button is provided, actuation of which simulates a ground fault to enable a user at any time to determine whether the ALCI is working properly.

Abstract: A leakage current interrupter device for use with appliances. The device of the present invention includes a switching device having an electromagnet which is energized by a sensing circuit upon the detection of leakage current or a ground fault condition. The magnetic field generated by the electromagnet moves a lever arm to instantaneously interrupt the flow of current through the circuit to disconnect the appliance from the power supply.

Abstract: A circuit breaker panel system supplies power to plural circuits that are ground fault protected and plural circuits that are not ground fault protected. The panel system has two sections. One section, which is not ground fault protected, contains a ground fault circuit breaker that supplies power to the second section, so that the entire second section is ground fault protected.

Abstract: A protective device for portable apparatus supplied from a high-voltage line is disclosed, which includes a connecting line from an electrical supply. The device also includes a protective switch with contact sets located in the supply lines and pre-stressed contact springs which are maintained in a closed position by a hoop-like fusible wire. An electronic firing circuit is disposed on a flat plate, together with the protective switch and the connections to the supply line and to the apparatus. The two-pole outlet of the firing circuit terminates in contact lugs with which the ends of the fusible wire can be connected mechanically and electrically. The circuit plate is, preferably, seated in the housing of a right angle plug, the contact pins of which are cast or pressed into the bottom of the housing and support the circuit plate while, at the same time, their heads constitute the opposite contact for the contact springs of the protective switch.

Abstract: The present invention describes a safety device for a socket portion of an electrical cord. The safety feature involves the positioning of a conducting ring around the positive slot on the receiving socket. The conducting ring is grounded, and when used in conjunction with a ground fault interrupter, prevents the completion of an electrical circuit through the child's saliva from the positive contact in the socket and the flesh of the child's mouth.

Abstract: An electrical safety device for use in power tools that is designed to automatically discontinue operation of the power tool upon physical contact of the tool with a concealed conductive material. A step down transformer is used to supply the operating power for a disconnect relay and a reset relay. When physical contact is made between the power tool and the conductive material, an electrical circuit through the disconnect relay is completed and the operation of the power tool is automatically interrupted. Once the contact between the tool and conductive material is broken, the power tool can be quickly and easily reactivated by a reset push button activating the reset relay. A remote reset is provided for convenience and efficiency of operation.

Abstract: When equipped with this improvement, a Gound Fault Circuit Interrupter will continue to monitor its protected circuits after tripping and automatically reset itself to restore power when no fault conditions are detected or when detected faults do not exceed a predetermined conduction level and are determined to be non-hazardous. The reset circuit shunts the tripped GFCI relay to pass a safely limited test current into the otherwise disconnected circuits of electrical utilization devices to determine the absence or the extent of fault conditions and is substantially fail-safe in regard to its own function. Four of the embodiments show the circuit as incorporated into the circuitry of an electrically resettable GFCI and a fifth as contained within an attachable enclosure.

Abstract: A leakage current preventing means for a drier includes a power circuit connected to an AC source, a touch control circuit connected to the power circuit and having a touch control IC and a touch control terminal capable of actuating the touch control IC, an output circuit connected to the touch control circuit and having a control medium which can be triggered into conduction by a pulse output from the IC and controls two junctions of the fire and ground wires from the AC source for being power supplied, and a leakage current detecting circuit connected to the touch control circuit and including a sensor for detecting an impedance change in the drier and an actuating medium capable of being energized into conduction in response to the impedance change to enable that the IC has no voltage output which results in non-conduction of the control medium which in turn results in no possible leakage current between the two junctions.

Abstract: A loss of neutral or ground protection circuit is disclosed which uses a simple capacitive circuit which discharges through the neutral or ground leads in normal conditions, and in the event of loss of neutral or ground charges sufficiently to trip a circuit breaker. The protection circuit may include other circuits such as ground fault detection circuits and may be in a one or three phase system. By virtue of the fact that a capacitive circuit is used to trip the circuit breaker, an inherent time delay is involved and thus the circuit breaker will not be tripped as a result of a momentary loss of neutral or ground. This is particularly important where continuity of operation of a load is important.

Abstract: A protective grounding and referencing arrangement for a high-voltage, high-energy bulk supply is provided in the present invention. Isolation from ground is provided through the use of an isolation transformer connected between the a-c utility supply and the rectifiers which are provided for conversion to d-c. The d-c bus and its energy storage capacitors are then referenced to ground by a high resistance divider network. In such an arrangement the likelihood of an insulation breakdown to ground is significantly reduced. More importantly, in the event that such a breakdown should occur from one or the other terminal of the d-c bus the fault currents that result are limited by the referencing arrangement to a safe level. The energy hazard is thus very significantly reduced for the equipment.

Abstract: A circuit breaker warning and control relay provides visual indication of an impending overcurrent condition. Sufficient time is thereby allotted for manual intervention to prevent damage to material and equipment utilized within sensitive manufacturing processes. The relay can be arranged to automatically shut-down selected equipment in a predetermined order for load-shedding implementation.

Abstract: A safety device to protect a piece of domestic electrical apparatus connected by means of a flexible supply lead to a plug to be attached to a conventional mains outlet. Between the pins of the plug and the exposed electrical working components of the apparatus is provided an on-off switch which will isolate the electrical operating components from the mains supply when the switch is in the "off" position. Sensor means are positioned within the piece of domestic electrical apparatus adjacent any exposed electrical components and control means for detecting a path of conduction between the sensor means and those exposed electrical components. Magnetically controlled release means including a permanent magnet and an electrically induced magnetic field in opposition thereto, preferably a DC motor provides movement when energized by the control means when the latter detect a path of conduction.

Abstract: A fail-safe immersion detector has a reset button which may be operated to return an appliance to operation after an immersion-caused short circuit has disappeared. However, if the short circuit remains, an operation of the reset button has no effect. Therefore, the user cannot defeat the fail-safe detector by the expedient of taping or otherwise holding down the reset button. A rocker switch enables a testing of the immersion detector, to be conducted to either side of the A.C. power line while preventing a short circuit across the line if an effort is made to simultaneously conduct tests to both sides of the line. Two test wires extend from the detector through the power cord to the appliance, where they are joined. The immersion detector operates via one of the two wires. The rocker switch conducts the test via the two test wires in series. Therefore, the rocker switch controlled test verifies the integrity of the one test wire.

Abstract: Positive assurance of correct connection, in supplying electrical utilization equipment from a current source, is provided when it is critical to safety and particularly when receptacle outlets are used or a fixed wiring installation required which may be subject to wiring error. An electromagnetic relay is employed to prevent equipment use and to provide audible indication in the event of hazardous connective error such as reversal of ungrounded and grounded neutral conductors and the omission of a grounding connection. The relay may be one that is also otherwise controlled for on-off power switching.

Abstract: An immersion detector comprises a pair of spring biased circuit breaking contacts for removing power from an appliance. The appliance has a sensing circuit which may become energized if it is dropped into a body of an electrically conductive liquid, such as a sink full of water. An SCR is connected to each side of the line and is triggered by an energization of said sensing circuit so that it is irrelevant which side of the line is hot and which side is at neutral. When either SCR conducts, a solenoid releases the spring bias which causes the circuit breaking contacts to fly apart.

Abstract: In an electrical appliance having an electrically conducting housing, defective grounding of the housing may result in a dangerous situation for the user. To prevent such a dangerous situation, the appliance, also having an internal, load circuit, is provided with a safety connector device, which connector device comprises an electric plug having two power contacts through which the load circuit is energized, and two auxiliary contacts. The two latter, auxiliary contacts are respectively connected to two separate points of the housing so that they are interconnected together through an interconnecting circuit including the electrically conducting housing of the appliance. One of the two auxiliary contacts is connectable to a ground for grounding the housing whereby a disconnection of the ground from the housing can be detected by sensing a discontinuity in the interconnecting circuit.

Abstract: An electric shock protector apparatus includes a circuit for detecting an electric shock current signal which has a frequency substantially higher than the line frequency of a power distribution system. The current of the power system is passed through a filter which eliminates the power supply frequency and produces a signal indicative of an electric shock current. The electric shock current signal is passed to positive and negative half-cycle operation signal circuits which transmit signals to a logic gate for operating a relay to disconnect the power source from the line conductors.

Abstract: A test circuit simulates the operation of a multipole electrical circuit breaker, and includes a pair of auxiliary terminals connected by a connection circuit to the input terminals of a bridge rectifier cell whose output is connected in parallel with the respective outputs to two other rectifier cells associated with current transformers. A first resistor delivers a first signal proportional to the maximum intensity of the mains currents. Diodes cooperate with a second measuring resistor of a residual earth leakage current discriminator. Reversing the direction of the test current flow in the test circuit is performed by simply changing the polarity of the test terminals, and enables overcurrent protection and earth leakage protection of the electronic trip device to be checked separately.

Abstract: Hand-held electrical apparatus having an electrical detector in the form of a conductive sensor adjacent to any exposed electrical part so that if the apparatus becomes wet or damp the water will form path of conduction between the exposed electrical part and the sensor. A conductive path from the sensor forming part of the supply lead to the plug, and the plug comprising normally closed mechanical switch at least in the live line from the mains supply to the supply lead to the apparatus and a control circuit connected to the said sensor by the conductive path which open the switch as a result of the conductive path having been formed from the exposed electrical part because of the presence of moisture. The switch comprises a length of wire holding electrical contacts closed against the action of a spring. The control circuit fuse the wire, however, to allow the spring to open the contacts when the conductive path is established.

Abstract: A microprocessor-based digital solid-state trip-unit for processing digital signals derived from analog signals supplied by current sensors. In order to reduce measurement error of the peak value of the signals due to signal sampling, the microprocessor samples a signal latched at the last peak. A countdown timer determines the latching time to include two or three peak values.

Abstract: The present invention teaches a system for protecting people and property against electrical shock which includes immersion detecting circuits, broken wire test circuits, electromechanical circuit breaking means including coil/plunger arrangements, and relay circuit breaking mechanisms cooperative with associated circuitry, all of which are able to be incorporated as a system wholly within the load (appliance) and its associated cord set (including a "plug").

Abstract: A leakage detecting device for electrical appliance is provided with electrodes (17) for detecting a state in which an electrical appliance such as a hair dryer is submerged in water. When the electrodes (17) are in a short-circuited state, relay means (3) is driven to open a contact (7). As a result, supply of the power supply voltage from a commercial power source (1) to the loads such as a motor (15), a heater (16) and the like is stopped so that an accident due to leakage can be prevented in such cases as a case in which the electrical appliance has been dropped into the water.

Abstract: Electronic system grounding includes two system grounding paths for card cage electronic modules, with a first grounding path through the card cage and a second grounding path through the system power supply. The two system grounding paths are used to minimize noise and reduce unwanted induced superimposed transient voltage levels.

Abstract: Digital solid-state trip unit designed to provide protection against phase faults, notably overloads and short-circuits and optional functions, in this case ground fault protection and load shedding and restoring functions. Two parameter input switches (72, 74) are assigned to the optional functions to display, in the ground protection option the ground protection pick-up and the ground protection time delay, and in the load shedding option, the load restoring pick-up and the load shedding pick-up. Each option has a software program stored in a non-volatile memory corresponding to it.

Abstract: A current sensor for use in a three phase ac system for producing a signal indicative of the average value of the sum of the squares of the ac current and of the phase imbalance between the three phases using two current transducers and an associated method.