Abstract: A protection device for an electric appliance comprising a differential transformer comprising a magnetic core disposed around a pair of wires leading to the appliance from the source and a sensing wire thereon; a solenoid driven switch for cutting off the source in response to a leakage current in the wires; an SCR which is normally non-conducting for connecting the solenoid to the source in the conducting state so as to cause the switch to be in a cut-off state; a voltage regulator for supplying suitable regulated voltage to an amplifier and a latched-trigger circuit; an amplifier connected to the sensing wires for providing a signal to the latched-trigger circuit; and a latched-trigger circuit for taking the signal from the amplifier and in response thereto provide a trigger signal to cause the SCR to be in a conducting state so as to operate the solenoid and cut-off switch.

Abstract: An alarm device adapted particularly for the indication of electrical leakage and mal-insulation of electrical appliances disposed in association with a marine tank for use in fish raising. An electrical leakage sensor unit is provided in the tank, to which are electrically plugged the illumination light, air pump, temperature controller, water filter member, germicidal light, so that an alarm signal led via an IC comparator and further to a sonic frequency vibrator for transformation and further to an signal amplifier and subsequently to a parallelly-connected buzzer and red-light indicator to simultaneously alarm the operator of the hazard of electrical leakage and mal-insulation.

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 for differential-protection of a bus bar having a plurality of terminals which includes a plurality of trunk lines, in which an impedance of a differential circuit connected in parallel to a current transformer provided in each of the terminals is changed depending on either a terminal voltage of this differential circuit, or another terminal voltage derived from a part of the impedances. Then, either a high impedance differential relay, or a low impedance differential relay is selectively available so as to confirmly detect a fault in the bus bar.

Abstract: A ground fault interrupter is adapted to be connected to a circuit having a supply current and a return current. The interrupter has a detection mechanism, including one or more than one cores, for detecting one or more than one ground fault currents. The core is composed of a metal alloy which is at least about 90 percent glassy and which consists essentially of a composition having the formula Co.sub.a Fe.sub.b Ni.sub.c M.sub.d B.sub.e Si.sub.f where M is at least one selected from a group consisting of Cr, Mo, Mn and Nb, the quantity a, b, c, d, e and f are in atom percent and the sum (a+b+c+d+e+f) is equal to 100 where "a" ranges from about 66 to 71, "b" ranges from about 2.5 to 4.

Abstract: A circuit arrangement for protection against fault currents in power supplies, having an energy storage means, such as frequency converters for the operation of three-phase motors. The arrangement comprises two identical detector windings in the supply lines leading to the power supply so that a differential current detector winding connected with such detector windings causes a circuit breaker device to be actuated when a given value is exceeded. This circuit breaker device interrupts all the supply lines between the power supply and a load connected therewith by means of switching paths. This ensures that despite the energy stored in the power supply there is rapid and reliable switching off of the load should a fault current occur.

Abstract: A remote control power disconnect circuit for providing a ground fault across an electrical outlet when an unsafe condition such as a lost neutral or shorting of the AC power switch is detected. The remote control power disconnect circuit is placed at each electrical outlet within a dwelling and applies AC power to the outlet only when an appliance (load) is plugged into the outlet and no fault condition is detected. However, when a fault condition is detected, the circuit also functions to apply a ground fault across the outlet and to shut-off the supply of AC power to the outlet. Then, once the fault condition has been remedied, the circuit may be remotely reset so that AC power may again be applied to the electrical outlet.

Abstract: An electrical receptacle affording ground fault protection includes a movable latch block having spaced surfaces supporting the free ends of a pair of parallel, electrically conducting arms. The arms are anchored at their opposite ends and are held in a flexed position, with a pair of contacts mounted on the movable, free ends of the arms in engagement with a pair of fixed contacts when the block is in a first, latched position. The latch is released in response to a sensed ground fault in the circuit, permitting movement of the block and free ends of the arms to disengage the movable contacts from the fixed contacts and open the circuit. The movable latch block is of dielectric material and includes a medial wall portion separating the two pairs of movable and fixed contacts, as well as the free ends of the arms. An end wall portion extends upwardly from and laterally across the forward edges of the spaced surfaces, perpendicular and integrally attached to the forward side of the medial wall portion.

Abstract: A ground fault circuit interrupter which continues to provide ground fault protection in the event of loss of neutral includes a blocking means formed by a pair of back-to-back Zener diodes which complete an energizing path for a circuit breaker on loss of neutral. The circuit interrupter also includes a standby rectifier circuit formed by a pair of diodes which complete a full wave rectifier having line and earth inputs in the event of loss of neutral.

Abstract: A ground fault current interrupter (GFCI) circuit is provided with the additional capacity of detecting and protecting against arcing between a power line and the metal sheath or cover of a power cable. An arc protection winding is located on the core of the GFCI differential transformer and is connected in series with a resistance between the metal sheath and a neutral or return line. By adjusting the number of turns of the arc protection winding and the size of the series resistance, the sensitivity of the arc portection arrangement to arcing current may be set at a desired level.

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: In an electrostatic paint spraying installation or the like, a high-tension voltage generator comprises a voltage rectifier-multiplier in a mobile subsystem and a grounding connection in a fixed subsystem. A conductive wire connects an input terminal of the voltage rectifier-multiplier to the grounding connection. When the high-tension voltage generator operates, a high-frequency alternating current residual signal injected into this conductive wire is sensed and measured. The measured value is compared against a reference value that may be variable. The high-tension voltage generator is disabled if the difference between the measured value and the reference value reaches or crosses a predetermined threshold.

Abstract: A principal aspect of the disclosure concerns housing means for an electrical receptacle comprising front and rear sections which are retained in assembled relation by snap fit coupling of terminal ends of post members on one section with edges of wall portions on the other section. The housing is disclosed in the context of a receptacle having ground fault circuit interrupting capability. Other disclosed features include snap-fit connection means for other components of a ground fault receptacle, a wiring board having solid state components of a ground fault circuit mounted on one surface and electro-mechanical components on the other, and a ground fault receptacle having both screw-type and push wire terminations. The foregoing features are made possible by a unique design and arrangement of parts which facilitates automated assembly of the entire receptacle.

Abstract: A ground fault detector employs a current feedback loop which makes use of a differential current sensing configuration to in essence increase the gain of the current feedback signal, thereby lowering the detector trip level when ground fault currents are present. In a preferred embodiment, ground faults are detected in a circuit having an AC-to-AC converter and a useful load by positioning a differential sensing configuration in the DC link of the AC-to-AC converter.

Abstract: A power bus fault detector for detecting faults in a predefined portion of an electrical power bus having at least one phase. Power feed lines are coupled to the predefined portion of the power bus by circuit breakers. Current transformers are used to detect the current flowing through each phase of each power feed line which is coupled to the predefined portion of the power bus. A summer generates a current differential signal for each phase that is equal to the sum of the currents detected by the current transformers. A fault detector generates a trip signal which causes the feed line circuit breakers to disconnect the feed lines from the power bus when a fault is detected in the predefined portion of the power bus. The fault detector includes a detector which detects when the current differential signal in any of the power bus's phases is substantially nonsinusoidal in shape.

Abstract: A differential current protection circuit breaker that operates as a magnetic amplifier has a secondary winding connected in series to a complex, predominately capacitive measuring impedance and a square wave generator. An evaluating circuit is connected at a tap and is actuated along a tripping device and a switch latch of a switching contact device. The evaluation circuit is blocked by a sensor that responds to extraneous current surges or voltage surges during a predetermined response time. A blocking device in the tripping device responds to the signals from the sensor.

Abstract: An inverter-type ballast has built-in differential current transformer operative to sense any substantive difference in the currents flowing from each of its two output terminals. If a substantive difference exists for more than just a brief period, a trigger circuit operates to disable the inverter, thereby to remove voltage from the output terminals.

Abstract: A method and apparatus for detecting a track and focus errors in an optical head comprises a step of dividing light beam which is reflected from a recording medium into at least a first, second, and third light beams belonging to first, second and third cross sectional regions thereof, and means therefor. The first region is expressed in its cross sectional position by the equations, ##EQU1## the second region is expressed in its cross sectional position by the equations, ##EQU2## the third region is excluded from said first and second regions and expressed in its cross sectional position by the equations, ##EQU3## where P is a pitch of pits or pregrooves of the recording medium, .lambda. is a wavelength of the light beam, .delta.

Abstract: Ground fault interrupting circuit breaker (10) includes a sensing coil (20) which is the secondary winding of a current transformer having a core (18) and includes a test coil (22) also wound about the core with load conductors passing through the core. A current sensing circuit (30) compares the output from the sensing coil to a reference voltage which is adjustable to set the sensitivity of the breaker. A test circuit (42) generates in the test coil a test current whch has its magnitude determined by the same reference voltage which determines the sensitivity of the breaker, thus causing the test current to automatically track the sensitivity of the breaker without separate adjustment.

Abstract: An earth leakage circuit breaker has a socket for connecting an appliance to be protected. A plug inserted in the socket depresses a plunger (34), tilting a cam (38) which acts through a striker (42) to momentarily close a relay, thus resetting the circuit breaker. When the appliance is unplugged the cam returns to its normal position, by-passing the striker (42) but closing a pair of test contacts. The reset and test functions are thus carried out without the need for separate buttons, and at times the load is disconnected, so that the circuit breaker contacts do not break load current when they open or close during resetting or testing.

Abstract: An adapter unit comprising a moisture resistant housing within which is carried an improved, self testing ground line fault interrupter device. The improved device is electrically interconnected with a connector carried externally of the adapter housing so that the unit can be plugged directly into a standard duplex outlet of an existing circuit. The apparatus includes circuitry that automatically tests the operability of the device when it is plugged into a duplex outlet without the need for manual manipulation of test buttons or other overt action by the user.

Abstract: A ground fault receptacle having novel mechanical members for latching and moving the movable, circuit-breaking contacts, and for protecting against line-to-line arcing as the contacts make and break. The movable contacts are carried on a pair of conducting, self-biasing, spring arms which are held in a flexed position by a latch block which moves with the arms and is retained in position by a stem on the reset button and cooperating latch member. The parts are constructed and arranged to permit the use of relatively large test and reset buttons which are centrally arranged on the front of a duplex receptacle housing.

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 ground fault simulation is produced responsive to a pool or spa water overtemperature condition, tripping the ground fault interrupter and shutting down the pump used to recirculate the water.

Abstract: A fault current circuit breaker for monitoring electrical circuits having a total current converter with a primary circuit including supply and return leads which are to be monitored and a secondary winding acting upon an electronic limiting value circuit which controls an electromagnetic retaining device. Switch contacts are provided for switching the circuit to be monitored when a predetermined fault current is exceeded. In order to enable self-monitoring, a current is briefly and periodically fed into an additional winding of the total current converter, with the current simulating a fault current, and a pulse voltage which appears at the output of the electronic limit value circuit due to the current in the additional winding is fed to an evaluation circuit, which causes the switch contacts to open in the absence of periodic pulses coming through the electromagnetic retaining device.

Abstract: The invention provides a safety device for an electric installation protection apparatus, comprising a residual differential current detector through which pass a phase conductor and a neutral conductor, and a processing circuit supplied by a rectifier bridge and connected to the phase and neutral conductors. It further comprises biasing and safety circuits formed by a static bidirectional switch connected between a ground connection and the AC terminals of the rectifier bridge.

Abstract: A system for detecting ground faults in circuit breakers having electronic trip units tied together by a low impedance common or circuit ground conductor. A complete electrical path between two circuit breakers is created when the secondary winding of the instrument current transformer of each circuit breaker is grounded as required by National Electrical Code rules. This can cause the ground fault sensing apparatus to inaccurately reflect the ground fault levels of the circuit breakers. The summing transformer of this invention includes a first primary winding which sums the currents through each of the phase current transformers and a second primary winding which indicates the current through the neutral conductor. The second primary is grounded, the ground does not provide a return path for the current between the two breakers since the second primary is isolated from the other summing transformer windings which are electrically connected to the circuit breaker.

Abstract: Improved shock and electrical-fire protection circuits provide line-to-ground plus "line-to-line" fault protection in a power system, and monitor conditions after protective interruption to safely provide automatic restoration of current when the fault is cleared. Both full-wave and half-wave circuits employ less expensive component combinations, including rectifiers and electromagnetic relays, to carry and switch load current. Protection is provided against the possibility of semi-conductor failure and the hazards associated with severed power conductors. A specialized resistance network fault detector for sensitizing enclosures, a hybrid zero sequence current transformer system and polyphase supply provide additional features.

Abstract: A method for reducing voltages required by in-place proximity-effect circuits includes providing uninsulated conductors which extend from a main transformer station to remote feed-node locations for connection to insulated conductors within a heat-tracing pipe.

Abstract: In a ground fault circuit interrupter having a solenoid with a moveable core, an electronic circuit detects a fault. The detection circuit also inhibits the solenoid from opening a pair of latching contacts until there is sufficient electrical energy to insure that the kinetic energy of the solenoid will cause the contacts to latch open.

Abstract: In a ground fault circuit interrupter (GFCI), a pair of flexure arms having moveable contacts disposed thereon are deflected in response to the activation of a solenoid having a moveable core. The core of the solenoid causes a pair of cam actuators which are preferably coupled together by a catcher to rotate. The rotation of the cam actuators causes the deflection of the flexure arms, thereby separating the moveable contacts from the stationary contacts and interrupting the flow of current. The activation of the solenoid is controlled by an electronic module. The electronic module includes a detection circuit which inhibits the solenoid from opening the contacts until there is sufficient electrical energy to insure that the kinetic energy of the solenoid will cause the contacts to latch open. The electromechanical current interrupter and the electronic module are disposed within a housing that can be mounted within a standard electrical receptacle box.

Abstract: An electronic ballast is adapted for operation on regular 120 volt/60 Hz power line voltage and comprises: (i) full bridge rectifier means, (ii) ripple filter means consisting of an LC circuit series-resonant at 120 Hz, (iii) self-oscillating inverter means operating into an LC output circuit parallel-resonant at about 30 kHz, and (iv) means to disable the inverter in case a 30 kHz ground-fault current flows from its output circuit. A key element in achieving high reliability as well as high durability relates to the use of the series-resonant LC circuit instead of the conventional electrolytic capacitor for DC voltage ripple filtering. A key element in achieving high efficiency relates to the use of ground-fault interruption to achieve the required safety from electric shock hazard, thereby obviating the need for the more conventionally used isolation transformer with its attendant added cost and inefficiency.

Abstract: In a differential-type protective relay actuated to generate a signal necessary for the protection of a bus of an electric power system when a troubled current has flown through the bus, a gapped first transformer is used to receive an output from a current transformer which is adapted to detect each current in the bus. Each output of a first detection element, which is actuated when the output of the first transformer is higher than a preset level, is fed out to the exterior only when a value obtained by subtracting the sum of the maximum of the output of the first transformer and the value of a signal obtained by shifting the phase of the output through a predetermined angle from the value of a signal obtained by subjecting the output of the first transformer to full-wave transformation is equal to or lower than a preset value.

Abstract: A ground fault module is designed for ease of assembly within a ground fault circuit breaker. The module houses the pre-assembled signal processor module, which contains the ground fault circuit interruption logic, along with the mechanical components required for translating the trip initiating response from the signal processor solenoid to the circuit breaker operating mechanism. The ground fault test button and related circuitry are also supported within the ground fault module.

Abstract: An electronic ballast is adapted for operation on regular 120 Volt/60 Hz power line voltage and comprises: (i) full bridge rectifier means, (ii) ripple filter means consisting of an LC circuit series-resonant at 120 Hz, (iii) push-pull inverter means operating into an LC output circuit parallel-resonant at about 30 kHz and operative to provide a 30 kHz voltage at an output that is substantially balanced with respect to ground, and (iv) means to disable the inverter in case a 30 kHz ground-fault current flows from this output. A key element in achieving high efficiency relates to the use of ground-fault interruption to achieve the required safety from electric shock hazard, thereby obviating the need for the more conventionally used isolation transformer with its attendant added cost and inefficiency.

Abstract: The neutral excitation and differential current transformers of a ground fault circuit breaker are arranged for automated assembly onto the signal processor circuit board to complete the signal processor module prior to insertion within the ground fault circuit breaker housing. Electrical interconnection between the transformers is made by a unitary conducting strap having means therein for receiving the circuit neutral conductor. The completely assembled signal processor module is connected with the circuit breaker components by means of a single wire.

Abstract: A two pole ground fault circuit breaker is provided by the attachment of a power supply module and a second single pole circuit breaker module to a completely assembled single pole ground fault circuit breaker. Electrical interconnection between the signal processor circuit within the single pole ground fault circuit breaker module and the second pole is made by a first pair of conductors. Interconnection between the power supply module and the single pole within the ground fault circuit breaker is provided by a separate pair of conductors.

Abstract: Differential current static trip circuits interconnected with upstream and downstream current sensing transformers in a protected system provide automatic coordination of the downstream static trip circuit breakers. The differential current transformer associated with the breakers vectorially sense the difference between the upstream breaker currents and the sum of the downstream breaker currents. The output is processed within the trip circuits for I.sup.2 t and fixed time band delays to insure that the downstream breakers clear the fault.

Abstract: A ground fault interrupter is rendered less sensitive to electrical noise by a densensitizing subcircuit. During the time the current to the load is interrupted a control chip is neither fully off nor fully on but is only slightly powered, that is it is desensitized. An LED indication is provided during the existance of a fault.

Abstract: A ground fault current interrupter circuit is provided in which open neutral and open ground conditions create actuation of the interrupter circuit, as well as a ground fault. This is achieved by utilizing a supplemental secondary winding on the differential transformer of a common type of ground fault interrupter circuit. An open neutral lead or an open ground lead produces a current flow through the supplemental secondary winding that induces a trip signal in the secondary winding to initiate opening of the power line. In a second embodiment the supplemental secondary winding induces a trip signal in the transformer only for an open ground lead, while tripping for an open neutral is achieved by directly gating an SCR switch. The circuit arrangements also protect against other conditions, such as a potential in excess of a predetermined voltage between the neutral and ground leads or a reversal of the input connections.

Abstract: A wall socket type ground fault circuit interrupter having a pair of sockets, a reset button and a test button that are accessible from the front of the interrupter. The interrupter has latched snap-acting contacts and a novel latching relay structure for releasably maintaining the snap-acting contacts in a circuit making position. The snap-acting contacts permit all of the components including the monitoring toroids and the power supply to be respectively located and connected at the load side of the snap-acting contacts so that all of the circuits of the interrupter are deenergized when the contacts snap to a circuit opening position. The snap-acting contact mechanism and relay are provided with structures which provides the interrupter with a trip-free mode of contact actuation and accordingly a tease-proof snap-acting contact operation.

Abstract: A circuit including a differential transformer for sensing an imbalance in the current flow through hot and neutral wires connected between a power source and load and a relay operable to break the connection in response to an imbalance of predetermined magnitude. The two movable relay contacts are placed directly in the two wires and are normally open, being closed when power is supplied to the relay coil, the input side of which is connected to a switching transistor. Features include connection of the relay coil as a series pass element in the feed circuit to reduce power dissipation and heat, decreasing the likelihood of contact chatter or welding, providing increased protection for the switching transistor without increasing relay contact opening time, and providing fail-safe operation for all of the more common types of failures in the protective circuitry. Open neutral and grounded neutral protection are also provided.

Abstract: A proximity effect heat-tracing system in which proximity effect heat-tracing circuits are fed in either direction from a plurality of feed points connected to a single main transformer to increase the length of pipeline supplied by a single main transformer. A secondary transformer interposed between a main transformer and a plurality of feed points reduces the voltage required to be applied to a proximity effect heat-tracing system of a given length. Two or more proximity effect heat-tracing systems used along the same length of pipeline, employ neutral conductors having approximately the same diameter as "hot" conductors where the secondary of the main transformer in each system is 180.degree. electrically out of phase with the secondary of the main transformer in the other system.

Abstract: A resettable circuit breaker has a pair of normally closed contacts through which a load is connected to a power line and means for opening the contacts in response to a predetermined change in electrical current flowing to and from the power line. One of the contacts is mounted on a rocking member which is maintained between a pivot on the base of the apparatus and the armature of a latching solenoid responsive to the predetermined current change by a spring assembly which causes the rocking member to rotate about the pivot means thereby opening and closing the contacts depending on the position of the armature.

Abstract: Methods and apparatus for detecting abnormalities in proximity effect pipeline tracing circuits by coupling conductive elements carrying proximity effect circuit currents and having opposite polarities. These conductive elements are coupled to an additional conductive element which is in turn connected to a system for detecting current so that when the difference between the proximity effect circuit currents is non-zero, the current flows through the additional conductive element and is detected by a relay or ammeter.

Abstract: An inverter-type ballast has built-in differential current transformer operative to sense any substantive difference in the currents flowing from each of its two output terminals. If a substantive difference exists for more than just a brief period, a trigger circuit operates to disable the inverter, thereby to remove voltage from the output terminals.

Abstract: A ground fault circuit interrupter (GFCI) yoke with integral grounding screw and simple staked ground receptacle stab arrangement provides the device grounding features. The mounting screws that are attached to the yoke by means of staples provide a wall box self-grounding feature. A push-to-test arrangement is provided by a neutral strap and test contact attached to the line receptacle stab through a current limiting resistor. Depressing a test button energizes the test circuit by electrically connecting the test contact with the neutral strap. The combination of the line and neutral receptacle stabs with the line and neutral moveable contact arms and the arrangement of the receptacle stabs in alignment with the receptacle plug-in slots allows the push-to-test and interrupter contacts to be assembled within the GFCI enclosure without additional wiring.

Abstract: An automatic domestic power line breaker comprising a current-to-voltage converter to which is applied an input signal obtained from the secondary of a differential transformer coupled to the power line. The converter output is coupled through a low pass filter to a rectifier, the output of which is connected to a function generator, which provides an output signal comprising a voltage having a slope proportional to the peak amplitude of the rectifier output signal. The function generator output is applied to a first input of a comparator having a second input to which is applied a d.c. threshold voltage. The comparator output signal is applied through an amplifier to control the state of a set of normally open relay contacts series connected in the power line conductors. A feed-back diode shunts the first input and output of the comparator to lock the relay contacts in the open state if the breaker has controlled opening of the contacts.

Abstract: A current monitoring circuit of a ground fault detector which receives its input from the secondary winding of an annular core transformer through which extends the current carrying leads being monitored. A resistor and capacitor are connected in series between the secondary winding and an AC amplifier to form an RLC band pass filter to minimize the circuits sensitivity to noise outside of the band of frequencies of interest. The sensitivity of the circuit to temperature changes due to fluctuations of the inductance is reduced by choosing an inductance value sufficiently high to ensure that it is not reduced to below a critical level at which sensitivity is effected.

Abstract: A compact operating mechanism for a ground fault circuit interrupter comprises a pair of main and reset slotted latches arranged under a crossarm and over a latch plate on a spring-loaded latch pin. The mechanism is reset by interference between a neck portion on the latch pin and a surface on the reset latch. The mechanism is latched by interference between the surfaces on a pair of upright posts on the latch plate and a surface on the main latch.