Abstract: Arrangement for arcless interruption of a-c load current in response to a current interruption command. Separable contact means serially connected with controlled impedance means, and parallel connected diversion means are intermediate the a-c source and the load. The controlled impedance comprises field effect transistors (FETs). Since FETs usually have only a single inherent junction, at least a pair of the FETs are oppositely poled so that load current can be cut off notwithstanding the direction of current flow when interruption is commanded. The pair of FETs may be connected back to back. An alternative embodiment has two branch circuits each comprising a FET and a separable contact means. Upon interruption load current is sequentially transferred from one to the other branch circuit and then to the diversion means.

Abstract: A control device and system for an appliance and methods of making the same are provided, the control device having a control unit to energize the coil of a relay with a power source at substantially a desired lead point on the voltage wave cycle thereof so as to tend to cause the contacts of the relay to subsequently close substantially at a certain point on the voltage wave cycle each time a load is to be interconnected to the power source whereby a lag time period exists between the desired lead point and a certain point, the control unit having a sensing unit to sense the lag time by detecting when the coil current of the relay coil decreases momentarily by the contacts initially closing during that particular cycle of operation of the control device, the control unit having a unit to automatically adjust the desired lead point should the sensed lag time on a certain previous cycle of operation not cause the contacts to close substantially at the certain point in order to tend to cause the contacts to clo

Abstract: When the runner of a linear motor having a long stator which is divided into sections crosses from a first section to a second section, an inverter power supply, which was providing current to the first section via a first switching unit having a relay, is initially gated out. Then the main relay contact paths in the first switching unit are opened and main relay contact paths in a second switching unit for the second section are closed. Only then is the power supply gated in again.

Abstract: The invention relates to a circuit arrangement for switching current from a contact to a thyristor connected in parallel to the contact. In the inventive circuit arrangement ohmic resistances (7, 8, 9, 10) are connected in parallel to the contact (1), whereby each ohmic resistance (7, 8, 9, 10) can be individually disconnected by means of a delayed-opening contact (3, 4, 5, 6) and the disconnection times are staggered. In this manner, it is possible to accomplish stepwise current switching and thus reliably prevent arcing at the contact (1).

Abstract: A relay control for a cooking appliance having a heating element includes a sensor for detecting the occurrence of an arc upon a change of state of a relay coupled between the heating element and a power supply. Upon detecting an arc, the sensor provides a timing signal which is coupled to a microprocessor that controls the energization and deenergization of the relay. The microprocessor is responsive to the timing signal from the sensor to determine the time delay between the last energization/deenergization of the relay and the changing of the relay's state. From the time delay, the microprocessor determines a delay constant. Subsequently, the microprocessor energizes the relay at a time after the detection of a zero crossover point of the power supply signal, wherein the time is equal to the determined delay constant to cause the relay to change state at or slightly before a zero crossover point of the power supply signal.

Abstract: The very fast circuit breaker assisted by semiconductor electronics. A piston 21 slides in an insulating housing 20 and along a center shaft 22. The piston 21 has of an exciting winding 25 and a magnetic yoke 26, which by cooperating with an armature 28, join the piston 21 to the center shaft 22, a shoulder of which renders possible the holding of a repulsion disk 34. The repulsion disk carries the moving contacts 35 and 36, which cooperate with the stationary contacts 37 and 38, when the piston is in its high position under the effect of a locking spring 24. Upon the injection of a current into the repulsion coil 45, the repulsion disk 34 is violently repulsed in the downward direction, while jumping the electromagnetic lock established between the magnetic yoke 26 and the armature 28. An admission of compressed air through an orifice 27 permits the descent of the piston 21.

Abstract: A method and apparatus in a control system for an electromagnetic contactor for reducing multiple re-ignitions incorporates a regulated source of electrical power coupled to a contactor actuating coil through a controllable switch. The switch is used to regulate coil current to a desired value whereby opening time of the contactor can be determined within a defined range. Alternating current through tips of the contactor is monitored and each zero crossing of the current wave form is determined. The control system responds to a command to open the contactor tips by coordinating such opening with the zero crossings of the current wave form whereby the contact tips separate within a predetermined phase angle prior to a zero crossing. The system also includes apparatus for detecting a fault current of the alternating current in the contact tips and for inhibiting operation of the contact tips for a predetermined time interval in order to allow fuses to clear the fault prior to opening the contactor.

Abstract: A reduced arcing contact switching circuit. It is desirable to control the switching of electrical contacts so that opening and closing occur at the time when zero power is being transferred to the load so as to substantially reduce arcing at the contacts and thus extend contact life. In a purely resistive circuit, for example, the supply voltage and current will be in-phase and contact switching should occur when the current and voltage signals pass through zero degree phase angle. Control of contact switching is accomplished with this invention by producing a count value that represents the phase angle at which contact movement should be initiated, so that the actual closing or opening will occur at the desired phase angle. When the count value and a preselected count are approximately equal, a flip-flop is enabled to pass the control information (open or close contacts) to a relay driver. The relay driver energizes or deenergizes (as the case may be) the relay to open or close the contacts.

Abstract: An electrically operated control device and system for an appliance and method of operating the same are provided, the system comprising a power source of alternating electrical current that has a repeating voltage wave cycle and a repeating current wave cycle, a load for using the electrical current to provide an output of the load for the appliance, a relay having normally open contacts and a coil for closing the contacts only when the coil is energized, an electrical circuit for interconnecting the power source to the load through the contacts only when the contacts are closed, and a control unit for causing the coil to close the contacts substantially at a certain point on the voltage wave cycle each time the relay coil closes the contacts from the open condition thereof whereby the current flow through the contacts at each closing thereof is at substantially a desired level thereof.

Abstract: A zero-current arc-suppression circuit breaker arrangement having a series circuit including a capacitor power source previously charged and a switch connected in parallel with a series circuit formed of a circuit breaker and a diode. Upon operation, the capacitor power source provides a reverse current for reducing the current flowing to the circuit breaker to a zero-current level and the diode maintains the circuit breaker current at the zero-current level for a predetermined period of time. When the contacts of the circuit breaker are separated during this period, no arc plasma is generated to protect the circuit breaker from damage.

Abstract: A circuit arrangement for large power transformers with a low-voltage winding, a main high-voltage winding and a step winding as well as a step switching device at a Y-point side thereof, includes, at a location between a point connecting the step winding to the high-voltage main winding and the Y-point of the transformer, a capacitor in series with a resistor is connected electrically parallel to respectively current-carrying steps of the step winding, the capacitor and the resistor being of such dimensions as to decrease resonance amplitudes of the connecting point to ground, the capacitor being constructed of spirally wound strip lines formed of a resistance alloy, the strip lines being also of such dimensions as to reduce resonance amplitudes of the connecting points.

Abstract: Synchronous circuit interruption is provided by operation of a diversion circuit for diverting most of the circuit current away from a pair of series-connected electrical contacts over to a solid state current interrupter prior to energizing a contact operator to separate the contacts to interrupt the remaining circuit current. To ensure arcless contact separation, the contact operator is arranged electrically in series with the solid state current interrupter which ultimately dissipates the system energy within a voltage dependent element. The arrangement of the contact operator circuit in series with the solid state current interrupter synchronizes the operation of the contact operator to ensure that the contacts are separated immediately after the circuit current has become diverted.

Abstract: A power control and diagnostic arrangement illustratively embodied in an electric range having multiple surface heating units which are selectively coupled to an AC power supply by commutated relay switching circuitry. The commutated relay switching circuitry includes two switching networks. Each network includes a diode commutated master relay serially connected to a pair of pilot relays. Each pilot relay is serially connected to one of the surface units. Timing and control circuitry periodically interrupts operation of the power circuit in a normal mode to operate in a diagnostic mode. In the diagnostic mode the relays are switched in a predetermined sequence to test for a short circuit failure of the master relays or commutated diodes, an open circuit failure of the diodes, an open circuit failure of the master relays, a short circuit failure of the pilot relays and an open circuit failure of any individual pilot relay.

Abstract: A method for interrupting an inductive load in a three-phase, high voltage network by means of a switch having a quick dielectric recovery, in particular a vacuum switch, in which two of the three vacuum switches, having a quick dielectric recovery, open at least 1/3 of a cycle of the network frequency later than the first vacuum switch, augmented with the minimum arcing time in the first vacuum switch, in order to prevent high over-voltages, caused by virtual chopping.

Abstract: A switch comprises a mechanical switch element having contacts and a semiconductor switching element, the mechanical switching element and semiconductor element being connected in series or in parallel with each other with respect to the output terminal and integrally formed in a housing. The semiconductor element and the connections thereto are embedded in an insulating material within the housing.

Abstract: Apparatus for a redundant power supply comprises a receptacle and a pair of power supply inserts received therein and having connectors for the input voltage and for the output voltage. The outputs of two or more such power supply inserts are directly connected in parallel to one another. To this end, differently designed or arranged contact members for the input voltage and for the output voltage are provided. In a preferred embodiment, so-called leading contacts are employed for a charging current at the output side via a charging resistor before connecting the output of the insert being plugged in parallel with the output of an operating insert.

Abstract: Stationary contacts (12) of a multi-pole disconnect or safety switch are arranged to be engaged by one of a rotatably movable bridging contact (2) before engagement of the other end thereof with a second set of stationary contacts (10). Stationary contacts (12) of adjacent switch poles are positioned on alternate ends for increasing the phase-to-phase failure distance, and one stationary contact (10a) may be arranged to close one or two milliseconds late to produce single phasing for a short time under fault current conditions during which time current limiting fuses (14) begin to open the circuit.

Abstract: A generator circuitry for connecting a generator to or disconnecting the same from a bus connected to a power supply. The circuitry comprising a first disconnector, a breaker and a second disconnector connected in series with one another between the bus and the generator further includes a detecting circuit to detect the generator output and an operating circuit to prohibit an action of opening the second disconnector during detection of the generator output by the detecting circuit. Since the disconnector is opened in the state where the generator output is not detected, the disconnector is released from the duty to interrupt the charge current flowing to the interelectrode capacitance of the breaker, whereby the use of a small-sized disconnector is rendered possible.

Abstract: A DC power switching circuit connecting a load to a DC power source while suppressing arcing across a relay in the network. A normally open relay has its energizing coil connected to the control input of the circuit, the opposite end of the coil being connected to the gate of a silicon controlled rectifier. The SCR has its principal current conducting path connected between the load and the DC power source, for conducting current between the load and the power source during a first delay interval, thereby reducing the potential difference between the contacts of the relay so as to prevent its arcing during the closure of the contacts. An FET device has its principal current conducting path connected between the load and the DC power source and has its gate connected to a timer.

Abstract: A contact point structure for two pole or more than two pole switches and relays. Each pair of contact points has a different turn-off capacity and a different contact gap so that opening and closing the multi-pole switch will sequentially open or close the pairs of contact points thereby limiting arcing to only one pair of contact points.

Abstract: A circuit for the arcless de-energization of a direct current load receiving direct current from a rectified alternating current source. The circuit includes a means for rectifying alternating current from an alternating current source to provide direct current to the direct current load. The means for rectifying has a current flow controller, such as a silicon controlled rectifier, connected with each phase of the alternating current source. The circuit also has means for de-energizing the then conducting current flow controller in said means for rectifying, the means for de-energizing having a current flow controller, such as a silicon controlled rectifier. The circuit further includes a voltage detection device for detecting a predetermined voltage drop in the circuit; and a time delay device for regulating the activation of the means for de-energizing.

Abstract: A capacitor discharge circuit constructed by a combination of a mechanical switch and an electronic switch. The electronic switch is automatically turned on with a predetermined time delay after closing of the mechanical switch. The mechanical switch is used to completely separate a high voltage-large capacity capacitor from a load when the discharge operation is not required. The wear and tear of contacts in the mechanical switch can be avoided by the delayed operation of the electronic switch.

Abstract: A hybrid electrical current switching device comprises a triggerable solid-state current switch connected in parallel with a mechanical switch in which the current flow depends on the relative positioning of a liquid metal conducting medium. The solid-state switching device operates as a crowbar switch to mitigate effects of arcing.

Abstract: A driver circuit which is responsive to an input AC voltage for providing a drive signal to a load circuit for each activation of a switch. A triggering signal generated by a trigger circuit in response to the activation of the switch energizes a timing circuit during a negative cycle of the input voltage. A control signal from the timing circuit energizes a firing circuit for a selected time period. The drive signal is applied to the load circuit during the time interval in which the firing circuit is energized by the timing circuit.

Abstract: A.C. switching circuit capable of opening and closing contacts without generating any arc. When D.C. source restores from its interruption, the contacts are maintained in or shifted to a predetermined state. A change-over switch is provided for selecting as required whether the contacts are to be forcibly opened or closed after the D.C. source interruption, or whether the previous state of the contacts is to be maintained.

Abstract: This electric circuit breaker comprises a main switch and two shunting paths respectively paralleling said main switch, each shunting path containing the series combination of an isolating switch and a diode assembly. The diode assemblies are connected in inverse-parallel relationship with each other. All of the switches are closed when the circuit breaker is closed, and during this interval substantially all current through the circuit breaker is through the main switch. During a circuit-interrupting operation, the three switches are opened. First, the main switch is opened to divert current into one of the shunting paths, and then the isolating switches are opened to complete the interrupting operation with assistance from the diode assemblies.

Abstract: An electrical switch or power controller is provided controlling the application of a source voltage to a load under the control of an electrical command signal, resulting in the development of a load current in response to said electrical command signal comprising: a semiconductor switching means having a predetermined non-bounce switching characteristic, being responsive to a semiconductor switching means operating signal for connecting said load to said voltage, an electromechanical switch means having a low voltage drop in a conducting condition, being responsive to an electromechanical switching means operating signal and being connected in parallel with the semiconductor switching means for connecting the load to the source voltage, control means responsive to the command electrical signal for providing the semiconductor switching means operating signal and the electromechanical switching means operating signal, whereby the semiconductor switching means predetermined non-bounce switching characteristics

Abstract: An arc suppression device (40) for protecting the load carrying contacts (30, 31, 32) of a power contactor (20) includes gate controlled semiconductor devices (TR1, TR2, TR3) connected in parallel with the contacts. A signal from a control circuit (45) causes gating current to be applied to the semiconductor devices nearly simultaneously with the application of current to and removal of current from the solenoid (25) of the power contactor. Circuit means (90) responds to the control signals to provide gating current for a limited period of time prior to, during and following the closing of the contacts. Gating current is not continued after the contacts have closed to protect the semiconductors from possible damage. Additional circuit means (110) responds to the removal of the control signal to provide gating current for a limited period of time prior to, during and following the opening of the contacts.

Abstract: A switching circuit having hybrid contactors connects the three output lines of a 3 phase AC power source to three input lines of a load, such as a motor and the like. A single pair of relay contacts is used to directly connect one output line of the AC power source to one input line of the load, whereas each of the other two phases of the AC power source are supplied to the load by one of a pair of pilot relay contacts in series with a diode-shunted one of a pair of master relay contacts. Only two extra pilot relays are used to provide a reversing function. The switching circuit further includes a zero-crossing detector, a phase-sequence detector, a control circuit including four flip-flops arranged in a tumble-down chain and a single distribution circuit having a data select circuit. The control circuit causes the making and breaking of the contacts at particular times, and in a sequence, such that arcing is prevented.

Abstract: A method and circuit for minimizing DC current offset generated by the voltage-integrating property of an inductive load. First, second and third hybrid contactors connect first, second, and third output lines of an AC power source to first, second, and third input lines of an inductive load. Each hybrid contactor includes a pair of relay contacts in parallel with a semiconductor switching unit having two antiparallel-connected silicon-controlled-rectifiers. A latching circuit and several delay circuits are used to turn on and off the hybrid contactors; the timing of the turn-on points is controlled relative to a zero-crossing of a voltage from the AC power source such that minimal DC offset current occurs.

Abstract: A circuit breaker apparatus of high voltage direct currents is connected in series with an external circuit comprising an AC-DC converting device connected to an AC power supply and a DC reactor connected to the AC-DC converting device, and comprises a circuit breaker connected in series with the external circuit, a disconnecting switch connected to the circuit breaker, and a series circuit connected in parallel with the circuit breaker and constituted of a blocking capacitor and a primary winding in a transformer. A charge storage capacitor is connected to a secondary winding of the transformer through a starting switch and polarity changeover switch, and an AC power supply for charging is connected through a diode to the charge storage capacitor.

Abstract: A synchronous closing system for high voltage circuit breakers is disclosed wherein the circuit breaker main contacts close within about 1 millisecond of a current zero in the current through a closing resistor in a 60 hertz system. Closing accuracy is obtained by delaying the release of a latch which holds the closing system for a given delay following the appearance of a closing signal, which delay enables hydraulic operating pressures to come to full value before permitting the hydraulic operation of the closing piston. The latch release instant is controlled from a signal derived from a zero cross-monitor circuit, which monitors resistor current and releases the latch at a time which allows contact closing at a subsequent current zero. The closing mechanism may be slightly jogged before full motion and during the delay time.

Abstract: A switching circuit for selectively coupling a load to an A.C. power source is disclosed. The switching circuit includes a diode-commutated master relay contact and a pilot relay contact coupled in series therewith. The master and pilot relay contacts are coupled between a load and the power source in such a manner that power is applied to the load whenever both the master and pilot relay contacts are closed. A timing and control circuit performs a switching operation to open the master relay contact during a first half-cycle of the A.C. waveform of the power source during which the commutating diode is forward-biased. The pilot relay contact changes state during the next half-cycle of the A.C. waveform and the master relay contact is reclosed during the following half-cycle of the A.C. waveform.

Abstract: The invention relates to a current cut-out circuit for a high-voltage electric installation, a current source being located on an input side and an earth fault possibly occurring on its output side. The circuit is characterized in that between the input and the output, it includes for each phase, in series, a cut-out device (1) with a high arcing voltage, said device opening very rapidly, and a circuit-breaker (2) which opens rapidly and, shunt-connected between the input of the cut-out device with a high arcing voltage and earth, a resistance (4) for limiting an earthing current which passes via an automatic cut-out (3) with a very short closing time and a short opening time.

Abstract: A motor is energized by a source through first and second transfer switches. Each transfer switch is operated by a switching transistor. The switching transistor for the first transfer switch is driven by a drive signal while the switching transistor for the second transfer switch is driven by the output of a delay circuit responsive to an excessively large current flowing through the motor. A self-holding switch is provided to connect the motor to the source through the second transfer switch.

Abstract: A method and apparatus for controlling electric current in loads that are essentially inductive, such that sparking and "ringing" current problems are reduced or eliminated. The circuit apparatus employs a pair of solid state switches (each of which switch may be an array of connected or parallel solid state switching devices such as transistors) and means for controlling those switches such that a power supply supplying two d.c. voltages (e.g. positive 150 volts d.c. and negative 150 volts d.c.) at low resistance may be connected across an essentially inductive load (e.g. a 6 gauge wire loop one hundred meters in diameter) alternatively and such that the first solid state switch is turned off and the second is turned on such that both are not on at the same time but the first turned on and the other on in less time than the inductive time constant (L/R) so that the load is essentially always presented with a low resistance path across its input.

Abstract: A solid-state circuit breaker is provided with circuitry for permitting off/on/reset operations actuated by a mechanical toggle control switch for close simulation of magnetic circuit breaker operation. A power continuity feature is provided for load power by locating the control switch so that it opens all of the circuit, except the static power switch branch, between the source and the load, to provide a high degree of fail-safe protection for the apparatus. The power continuity feature includes means for zero crossover synchronization both upon power-up and power-down conditions. A circuit lockout feature is used so that on power-up or turn-on, operation is delayed until the occurrence of an internal power-ready condition. On power-down or turn-off, there is means for circuit retention subsequent to switch opening and internal power removal in order to accomplish load turn-off at a desired zero crossover point of the load power through the power switch.

Abstract: A solid state circuit breaker is provided with circuitry for permitting off/on/reset operations actuated by mechanical toggle switch for close simulation of magnetic circuit breaker operation in three phase or other multiphase systems. A power continuity feature is provided for load power by locating the control switch so that it opens all of the circuit except the static power switch branch. The control switch is located between two of the supply voltage phases and the power supply for the control circuitry. The correct zero crossover of one phase is utilized to produce turn-on at zero degrees of that one phase while the other two phases are respectively at minus 120.degree. and plus 120.degree. without any significant impairment of overall circuit breaker performance. An overcurrent protection system is included that uses optical isolators with reduced sensing voltages developed directly from terminals of the power switch elements.

Abstract: A protective circuit is described for selectively applying power to a motor. The circuit includes a power switch which closes and opens to apply and remove power from the motor, and a control for diverting reactively inducted motor current from the power switch back to the motor via a current path when the power switch is opened. The control opens the current path when the power switch opens and remains open for a predetermined interval so that, when the motor is unenergized and mechanically rotated, the motor is not braked by current flow through the current path and the motor.

Abstract: Current interruption capability for short-line or terminal faults is achieved by connecting a fluid blast interrupter in series with a high current vacuum interrupter capable of withstanding the initial recovery voltage during such fault. The fluid blast breaker ultimately becomes able to carry the total recovery voltage by delaying opening of the vacuum interrupter for a fixed interval after opening of the fluid blast breaker has been triggered.

Abstract: A relay control circuit is disclosed in which a timer circuit is actuated by a reference clock pulse in synchronism with an AC voltage supplied by a commercial power supply. An output signal of the timer circuit causes current to flow in the coil of the relay thereby to close the contact of a relay. The invention further comprises a polarity-reversing device for reversing the polarity in accordance with the variations in the output signal of the timer circuit. The reference clock pulse is applied to the timer circuit through the polarity-reversing device.

Abstract: The power contactor for controlling the application of power to and the character of the current to a load includes a power relay having contacts connected between a source of power and the load, such as a motor or heater, with each of the contacts being provided with arc suppression means. A steering relay is provided to control the direction of current to a motor and thus its direction of rotation or the voltage applied to a heater. A control circuit insures that the steering relay contacts remain either open or closed while power is being applied to the load. The steering relay is provided with bracer bars to prevent short circuiting between relay contacts should any welding occur therebetween. The arc suppression means for each of the power relay contacts includes a solid state device, such as a triac, in parallel therewith, and auxiliary contacts for controlling the gating current to the triac.

Abstract: A vacuum switch system for interrupting electrolytic cell circuits designed to operate at very high current, relatively low DC voltage. The DC voltage is above the minimum cathode drop potential for the vacuum switch contact material. The system includes plural parallel circuit paths, with one of the parallel circuit paths including at least two serially connected vacuum switches. The operating means for opening and closing all the switch contacts includes means responsive to the opening of the vacuum switches to simultaneously open the serially connected vacuum switches in the parallel path.

Abstract: Apparatus for preventing the occurrence of possible transient phenomena in the circuit including a power source and its load connected thereto when the supply of electric power from the power source to the load, which has been interrupted, is restarted. The apparatus includes means for detecting the occurrence of the interruption of the power supply and means for memorizing the phase angle of the voltage or current of the power source at the time of the occurrence of the interruption of the power supply to maintain the circuit in off-condition. The apparatus further includes means for detecting the coincidence of the phase angle memorized in the memorizing means with a changing phase angle of voltage or current of the power source after the resupply of the electric power from the source to the load becomes possible whereby, upon detecting the coincidence, resupply of the electric power from the power source to load will be restarted.

Abstract: A tap-changing transformer system, utilized for voltage regulation of the line potential applied to a load from a source of energy, has a non-arcing switch to protect tap contacts during a tap change. A fail-safe circuit is utilized to determine that the non-arcing switch and its associated circuitry are operating properly before a movable tap contact is transferred from one stationary tap to another. In the event that the fail-safe circuit detects an improper operation of the non-arcing switch, the source is connected directly to the load to preclude the passage of any load current through the tap-changing transformer. A particular form of transfer switch useful in effecting the connection of the source directly to the load employs a current-limiting impedance arrangement.

Abstract: A hybrid AC power switching arrangement in which two ganged switch banks in series are employed along with a pair of reverse parallel (back-to-back) SCRs across each contact pair of the second switch gang. SCR control means and interlock control means are provided so that the first switch gang (closest to the power source) closes first, energizing the SCR control and permitting the SCRs to conduct load current in a corresponding phase leg, beginning at or near a zero voltage cross-over point. After all phase legs are conducting through the SCRs, the second switch gang is closed bypassing the SCRs. On circuit break, the second switch gang (i.e., the one closest to the load) is opened first, the load current diverting immediately through the SCRs for another interim period until the SCRs in each individual phase leg are extinguished as the instantaneous current in the corresponding phase lead passes through or near zero.

Abstract: Electrical control circuitry for driving a rotational print head to initiate an endorsement on a single side of paper checks traveling past the print head at a relatively constant velocity, including a bistable device operatively connected to control a ramp generator for accelerating the print head at a relatively constant rate from a stopped position to a present printing velocity and then decelerating the print head to a rest state at the same relatively constant rate after completion of document endorsement. The circuitry responds to closely-spaced documents entering the endorser by interrupting the head during its deceleration mode and maintaining the head at its interrupted velocity for a certain time delay in order to reaccelerate the head back to printing velocity at the same relatively constant rate in time for proper endorsement.

Abstract: The disclosure relates to a time-overcurrent relay utilizing successive linear time-current segments which approximate a non-linear, inverse time-current curve the linear segments are determined by subtracting a series of ramp like voltages of increasing magnitudes from a series of bias voltages, each of which is of substantially constant magnitude and which bias voltage magnitudes decrease in sequence by the peak magnitude of the preceding ramp voltage.

Abstract: The voltage dividing DC circuit breaker comprises serially connected high voltage and low voltage switches to carry load current. Serial capacitors are connected in parallel thereto and a crossed field switching device is connected in parallel to the low voltage switch. When the low voltage and high voltage switches are opened, current is forced through the crossed field switching device. When the crossed field switching device is turned off, the arcing high voltage switch is forced below its chopping current. The open circuit voltage is divided across the capacitors.

Abstract: An improved vending machine power switching apparatus in which a single power switching circuit is associated with a plurality of load selecting relay switches and a switching control circuit, in which the control circuit controls the order of switching of the power switch and relay switches, such that any relay switch is always closed before power is delivered to its associated load and is always opened after power is removed from the load, and the power is applied and removed by the power switching means.