Abstract: The measurement of analog coil voltage and coil current during the energizing of the circuit breaker coil that is connected to the output contact of a protective circuit breaker relay in order to detect an incipient failure of the circuit breaker mechanism.

Abstract: An apparatus for repeatably generating electrical arcs for testing an electrical switching device, such as an arc fault circuit interrupter, includes a stationary electrode and a movable electrode that is moved along a path of travel by an electromechanical device under the control of a controller that receives data from either a current measuring device or a voltage measuring device to detect the initiation of an arc. The movable electrode is caused to first make physical contact with the stationary electrode, and then is moved away from the stationary electrode until an arc is detected. Additionally, the movable electrode may be moved towards and away from the stationary electrode according to a test profile to control the magnitude of the randomness of the arc.

Abstract: A solenoid type switch has at least two driving coils. The driving coils turn off a switch with a current for example an overcurrent that flows in the switch. The driving coils are magnetized or demagnetized by a driving circuit so as to turn on or off the switch. The driving circuit magnetizes or demagnetizes the driving coils in accordance with a control signal supplied from a controlling circuit. Thus, the switch can be turned off with the current that flows in the driving coils.

Abstract: The patent describes an electric switchgear (10) with a pole of the switchgear filled with insulating gas, and it is provided with a monitoring device (14) for the insulating gas in the switchgear pole and with a test connection (28) for a testing device to test the monitoring device (14). A device (20) is provided that has a test connection (28). The device (20) is connected to the monitoring device (14) and the switchgear pole. The device (20) has a valve (23), with which the switchgear pole can be detached from the monitoring device (14).

Abstract: A method and an apparatus are disclosed for measuring contact erosion in an electrical switching device by a dynamic resistance measurement (DRM). To determine an overlap time and a contact erosion in an exemplary switching device, a change in current across the switching device can be measured indirectly by a measurement current being passed across the switching device and a parallel conductor, the change in current in the parallel conductor being measured. Exemplary embodiments relate, to the following: detection of a differential current measurement signal in the parallel conductor with the aid of a Rogowski coil; and selection of a parallel conductor resistance on an order of the switch resistance.

Abstract: A system for monitoring a circuit breaker that includes a monitoring device in electronic communication with the circuit breaker and a receiving device located separately from the monitoring device. The monitoring device receives data from the circuit breaker and wirelessly transmits at least a portion of the data such as one or more phase currents measured from a network which the circuit breaker protects, an ambient temperature within the circuit breaker, and/or data relating to a trip condition of the circuit breaker. The receiving device receives the transmitted data and displays all or a portion thereof. The monitoring device also includes a display that displays all or a portion of the data.

Abstract: A monitor circuit is provided which detects various incipient failure modes of a circuit breaker. The monitor circuit includes a processor and a primary circuit connected in circuit with the processor. The primary circuit may be configured for preventing transients and high currents associated with the operation of the circuit breaker from damaging the processor. A secondary circuit may be connected in circuit with the processor and the primary circuit. The secondary circuit provides an analog voltage input and a current input to the processor that is representative of an aspect of the circuit breaker and wherein the processor is configured to detect at least one failure mode of at least one circuit breaker from the analog voltage and current input.

Abstract: The present invention is directed to an electrical wiring inspection system. The system includes an electrical measurement apparatus having at least one load center connector configured to couple the electrical measurement apparatus to a load center, at least one branch circuit connective device configured to couple the electrical measurement apparatus to a portion of a branch circuit, and at least one electrical measurement circuit disposed between the at least one load center connector and the at least one branch circuit connective device. The at least one electrical measurement circuit is configured to perform a series of electrical test procedures to obtain a plurality of electrical parameters. A portable computing device (PCD) includes processing circuitry, a user interface coupled to the processing circuitry, and at least one communications interface configured to couple the portable computing device to the electrical measurement apparatus.

Abstract: A method of detecting or validating the architecture of a circuit breaker unit disposed within a circuit breaker assembly comprising a plurality of the circuit breaker units, the method comprising: tagging each the circuit breaker unit with an identification tag, the identification tag providing architectural information related to the circuit breaker; and reading the identification tag disposed on the circuit breaker, whereby the circuit breaker assembly does not need to be disassembled for detection or validation of the architecture of the circuit breaker.

Abstract: A voltage control apparatus checks a battery voltage when an automotive generator gradually increases its output to be within a predetermined range after temporarily stopping the generator. Then, the battery voltage is picked up to calculate the charge rate. Further, a first charge rate and a first residual capacity of the battery is memorized when the engine is stopped. Periodically, a pseudo-open circuit voltage is checked when a charge/discharge current fits within a predetermined small range while the engine is not running, and a second charge rate calculated based on the checked pseudo-open circuit voltage. A second residual capacity is calculated using the first charge rate, the first residual capacity and the second charge rate.

Abstract: An electronic filter for filtering the output signal of a current sensor of a circuit breaker is disclosed. The current sensor has an output signal characteristic similar to that of a Rogowski coil output signal characteristic that includes a third harmonic noise component in response to a switching primary current of the circuit breaker, and the circuit breaker has an electronic trip unit with an instantaneous pick-up setting responsive to the output signal of the current sensor. The electronic filter includes a first stage and a second stage. The first stage has a first transfer function that defines first characteristic poles and permits passage of the third harmonic noise component. The second stage has a second transfer function that defines second characteristic poles and filters the third harmonic noise component.

Abstract: The present invention is directed to a protective wiring device that includes a plurality of line terminals coupled to a plurality of load terminals by way of at least one conductive path. A miswire detection circuit is coupled to the at least one conductive path. The miswire detection circuit is configured to monitor signal propagation characteristics on the at least one conductive path and generate a miswire detection signal based on the signal propagation characteristics commencing each time source power is applied to either the plurality of line terminals or the plurality of load terminals. A fault detection circuit is coupled to the at least one conductive path. The fault detection circuit is configured to detect a fault condition propagating on the at least one conductive path. The fault detection circuit is configured to generate a trip signal in response to either the fault condition or the miswire detection signal. A circuit interrupter is coupled to the fault detection circuit.

Abstract: A method and apparatus for testing the loop impedance in residual current circuit breaker (RCCB) protected circuits is provided. An alternating test current is applied across the phase earth connections of a supply and a plurality of voltage samples are then taken across the connections. The voltage samples are subsequently transformed from time space to frequency space to allow the component due to the test current to be isolated. The loop impedance is then calculated.

Abstract: A tester for testing a circuit breaker includes a plurality of load elements each having a nominal fixed impedance and an electronic switch associated with each load element. The electronic switch, when turned on, electrically connects a corresponding load element in series with a circuit breaker load terminal and in parallel with none or with a number of other load elements. A controller turns on a number of the electronic switches selected to draw through a corresponding number of the load elements a test current selected as a function of a designated rated current for the circuit breaker and sufficient to trip open the same. A pulse width modulation circuit cooperates with the controller and with the electronic switches. The pulse width modulation circuit provides a constant magnitude of the test current to accommodate variations of the nominal fixed impedance or variations of the voltage of the load terminal.

Abstract: There is provided a method of testing an electrical switchgear system. A node in the electrical switchgear system monitors a power line signal and controls a breaker based on the power line signal. The method includes applying an analog signal to the node, and receiving data representing a status of the breaker. The analog signal simulates the power line signal.

Abstract: The present invention is directed to a circuit and method for self-testing a protection device for use in an AC power distribution system. The device is configured to be coupled between an AC power distribution system and at least one load. The method includes the step of introducing a simulated ground neutral fault during a first predetermined half cycle half cycle of the AC power. An attempt is made to detect the introduced simulated grounded neutral fault during the first predetermined half cycle half cycle. A fault condition is signaled if the introduced simulated grounded neutral fault is not detected within a predetermined period of time.

Abstract: A vacuum circuit breaker includes a line terminal, a load terminal and a vacuum interrupter having a vacuum envelope containing a fixed contact assembly and a moveable contact assembly moveable between closed and open circuit positions. The fixed contact assembly is electrically interconnected with the line terminal and the moveable contact assembly is electrically connected to the load terminal. An operating mechanism moves the moveable contact assembly between the closed and open circuit positions. An auxiliary contact indicates one of the open or closed circuit positions. An electro-optical voltage sensor determines a voltage difference between the line and load terminals, or the shield and one of the line and load terminals. A circuit determines no leakage or loss of vacuum of the vacuum envelope when the vacuum switch is intended to be in the open circuit position and when the voltage difference is greater than a predetermined amount.

Abstract: A portable circuit interrupter shutoff testing device and method, including a high current switch controlled by a timing circuit that allows current to flow through the switch and a small series resistance (in order to trip the instantaneous-trip function of the interrupter, as opposed to the overload-trip) for a short time period relative to the sine wave of the electrical power. A button activates the timing circuit which in turn activates the switch and current flows limited by the internal resistor of the device. By limiting the on time of the device to one or a few half cycles, the user can test if the circuit interrupter responds as quickly as specified by the manufacturer. A method includes receiving a stimulation indication, and selectively connecting an electrical load to wires connected to the circuit interrupter, wherein the electrical load is sufficient to trigger the instantaneous-trip function of the circuit-interrupter.

Abstract: A method of monitoring a power distribution unit (306) may include providing a power distribution unit frame (310), where the power distribution unit frame has a 2U form factor (312), and where the power distribution unit frame is coupled to mount in an embedded computer frame (102). An alarm module (418) may be coupled to a circuit breaker connection site (214) in the power distribution unit frame. The alarm module may detect whether a circuit breaker (416) is coupled to the circuit breaker connection site via a set of auxiliary contacts (439). If the alarm module detects the circuit breaker, the alarm module monitors a set of shelf conditions. If the alarm module fails to detect the circuit breaker, the alarm module does not monitor the set of shelf conditions.

Abstract: A portable circuit interrupter shutoff testing device and method, including a high current switch controlled by a timing circuit that allows current to flow through the switch and a small series resistance (in order to trip the instantaneous-trip function of the interrupter, as opposed to the overload-trip) for a short time period relative to the sine wave of the electrical power. A button activates the timing circuit which in turn activates the switch and current flows limited by the internal resistor of the device. By limiting the on time of the device to one of a few half cycles, the user can test if the circuit interrupter responds as quickly as specified by the manufacturer. A method includes receiving a stimulation indication, and selectively connecting an electrical load is sufficient to trigger the instantaneous-trip function of the circuit-interrupter.

Abstract: This invention is intended to reduce the cost by displaying the load information of a plurality of circuits with a single display device and transferring one of the two communication units in the measuring instruments from the measuring instruments to the display device to acquire the load information of a plurality of circuits. The display device and the measuring instruments are separated from each other, and the display device includes a plurality of communications units connectable with a plurality of devices, while each of many measuring instruments includes a single communication unit.

Abstract: The invention relates to a method, a computer programme and a device (2) for determining contact wear in an electrical switchgear (3) in an electric switchgear assembly (1) as well as to a switchgear assembly (1) with such a device (2). According to invention, for determining a contact wear status variable (Cwsum) a current measuring signal (Imess) is monitored for deviations (?) from an expected faulty switch-off current (If) and, in case of deviations, the status variable (Cwsum) is not immediately calculated from current measuring signal (Imess), but indirectly using a characteristic current value (Ichar). Embodiments, among other things, relate to: deviations by saturation of the current transformer (30) and maximal current measuring signal (Imax) as characteristic current value (Ichar); status variable (Cwsum) as a measure for arcing power during switching-off and, in particular, equal to a potential function (f(Imess)) of the switch-off current (Imess).

Abstract: An adjusting bolt is screwed into a nut attached to a dolly, and is disposed such that a central axis thereof is parallel to a closing and opening direction of a contact. A lever is attached to a shaft. An electrically-insulating rod is coupled to a first end of the lever, and a pin is mounted to a second end of the lever. The adjusting bolt is turned and lowered to lower the pin. The lever and the shaft are pivoted by the lowering of the pin, and the electrically-insulating rod is raised. Thus, a movable contact moves toward a fixed contact, moving the contact from an open state to a closed state.

Abstract: A method for testing high-voltage alternating-current power switches in a synthetic test circuit has the step of connecting a high-voltage oscillating circuit in parallel to a test switch Bt in a time interval before the current zero of an interruptible high current, which is determined by a half-cycle duration (Th/2) of the oscillating current (ih) less the duration of equivalence (?tse) of the sole flow of the oscillating current as sequential current in the test switch with a stress exerted upon the switch by the homogeneous current in a direct test circuit. The sequential-current flow duration of the equivalence results, at least approximately, from the comparison of the values of common physical stress parameters acting in the test switch during the test, on the one hand, in the synthetic test circuit and, on the other hand, in the direct test circuit.

Abstract: A system for testing and documenting the electrical wiring in a building, for example, includes a Portable Circuit Analyzer (PCA) that is connected to the building's Load Center through an umbilical cord. The PCA is in wireless communication with a hand-held computer device, such as a personal digital assistant (PDA) as now widely available, provided with custom software according to the invention. The electrician connects the PCA in succession to each circuit in the building, operating each switch, and each fixture or appliance, while recording the test results of the circuit element on the PDA. The PCA measures the resistance and length of each circuit thus established. When the test process is completed, the PDA is enabled to generate a complete schematic diagram of the building, including, for example, an identification of the branch circuit to which each fixture, outlet, appliance, or other load or connection point is connected.

Abstract: A method for determining the influence of one of a plurality of cathodic protection circuits along a pipeline includes switching one of a plurality of cathodic protection circuits off, while the remainder of the plurality of cathodic protection circuits are left on, with a portable pipe-to-soil potential measurement unit measuring the pipe-to-soil potential along the pipeline. From these measurements, a calibration curve is generated and an apparatus for monitoring the cathodic protection circuits is strategically positioned on the pipeline. The apparatus includes a remote monitoring unit having a pipe-to-soil potential measurement unit for measuring the potential between the ground bed and pipeline. The remote monitoring unit is off except while making measurements. The remote monitoring unit may optionally include a pipeline current measurement unit connected at a second connection point on the pipeline for measuring the current passing through the pipeline between the first and second connection points.

Abstract: According to one embodiment, the present invention provides a system for determining wear of an electrical element. The system includes a current source, a voltmeter and a control unit. The control unit is operable to couple the current source and the voltmeter to a first spare electrical element in a device under test, determine a characteristic physical property of the first spare electrical element and determine a wear characteristic for a primary electrical element in the device under test based upon the characteristic physical property of the first spare electrical element.

Abstract: The present invention is directed to an electrical wiring protection device for use in coupling an AC power distribution system to at least one electrical load. The device includes an automated self-test circuit coupled to the AC power distribution system. The automated self-test circuit is configured to generate at least one simulated fault signal during a first predetermined half-cycle of AC power. A detector circuit is coupled to the automated self-test circuit. The detector circuit generates a detection signal in response to the at least one simulated fault signal. An interval timing circuit is coupled to the test circuit. The interval timing circuit is configured to enable the automated self-test circuit to generate the at least one simulated fault signal during a first predetermined interval and not enable the test circuit during a subsequent second predetermined interval. The first predetermined interval and the second predetermined interval are recurring time intervals.

Abstract: Methods, computer program segment and apparatus for analyzing high voltage circuit breakers are provided. The method includes determining a circuit breaker contact closing time, determining a circuit breaker contact opening time, and determining a circuit breaker pre-insertion resistor resistance value using at least three voltage samples and three current samples to facilitate reducing an induced current measurement error. The computer program segment is embodied on a computer readable media and is programmed to determine a circuit breaker contact closing time, determine a circuit breaker contact opening time, and determine a circuit breaker pre-insertion resistor resistance value using at least three voltage samples and three current samples that facilitate minimizing an induced current measurement error.

Abstract: A method for analyzing an electrical contact pair is provided. At least one of the contacts is coupled to a line-side of the contact pair, and at least one of the contacts is coupled to a load-side of the contact pair. The method includes electrically coupling the load-side contact and the line-side contact to electrical ground, applying a test voltage across the contact pair while the line-side contact and load-side contact remain electrically coupled to electrical ground, triggering a contact pair operation timer at a start of a test, detecting at least one of a first closure of the contact pair and a first opening of the contact pair using the test voltage, and determining the timing of the contact pair based upon the operation of the contact pair operation timer.

Abstract: An electrical circuit test apparatus for testing a three-conductor electrical circuit outlet connected to an associated circuit breaker. The three-conductor connections are the electrically active (Hot), neutral and ground. Any suitable color-coding either national or international may, if desired, be used to identify the electrically active (Hot), neutral and ground electrical conductors. A three-conductor electrical cable is connected at one end to a three-prong plug. The other end of the electrical cable is connected to the electrical test apparatus that determines and indicates the current energized state of the circuit breaker.

Abstract: An arc fault interrupter tester creates a simulated arc fault current through a full wave bridge rectifier, a load resistor and a switch connected in series. These components are rated at currents and wattage well below the current of the simulated arc fault. Thermal management in the form of a temperature sensor and control pulse timing and duration prevent damage to the low-rated components.

Abstract: A circuit protection device connected between two lines of an AC power source self checks for an introduced simulated ground fault every half cycle during a period when a trip SCR cannot conduct. If the self check fails, the device is tripped on the next half cycle of different phase. Possible responses to the self check failure include lighting an indicator lamp and locking out the device reset mechanism.

Abstract: Methods, computer program segment and apparatus for analyzing high voltage circuit breakers are provided. The method includes electrically coupling each circuit breaker contact to ground, applying a test voltage across a circuit breaker contact, measuring an output voltage signal that is proportional to a capacitance of the circuit breaker contact, changing a state of the circuit breaker contact pair from at least one of an open position to a closed position and the closed position to the open position, and detecting a step change of the output voltage that corresponds to the change of state of the circuit breaker. A circuit breaker test device is provided. The device includes a test voltage source, a filter circuit, and an output circuit for measuring the circuit breaker contact pair capacitance, wherein the test voltage source and filter circuit are configured to be coupled to the circuit breaker contact pair during testing.

Abstract: A circuit analyzer tests a power circuit including an earth leakage ground fault circuit interrupter, a receptacle, and a line, a neutral and a ground electrically connected between the circuit interrupter and the receptacle. The circuit analyzer includes a plurality of pushbuttons for inputting a plurality of test requests. A microprocessor outputs a plurality of test signals responsive to the test requests. A plurality of load circuits selectively provide a load between the line and the neutral responsive to one of the test signals. A display confirms tripping of the ground fault circuit interrupter responsive to the load, in order to determine if the neutral is electrically connected to the ground between the circuit interrupter and the receptacle.

Abstract: A power switching control device and methods for using the same to control a magnetic actuator within a power switching device are disclosed. The power switching control device uses a series of modulated current pulses to control a magnetic actuator within a power switching device. The power switching control device inputs a power signal and applies a series of modulated current pulses through the coil of the magnetic actuator in a first direction such that the actuator moves from a first position to a second position. Certain operating characteristics of a power switching device can be ascertained by analyzing the impedance of the magnetic actuator coil within the power switching device. The power switching device control device also has an improved energy management system therein. In this manner, the controller includes a voltage regulator that has the ability to switch between operating modes.

Abstract: An apparatus and method for providing redundant protection to a fault detection/interruption circuit, thereby ensuring safe operation even in the case of a failure of the primary fault detection/interruption means. Upon the occurrence of a failure in the primary circuit interruption means, a secondary circuit breaker, or in some embodiments, a redundant primary circuit breaker release mechanism, serves to remove power from a protected outlet or output conductors.

Abstract: An apparatus and method for simulating arcing events for use in testing arc fault circuit interrupters. The apparatus and method utilizes a plurality of motion sensitive switches, for example, mercury switches or ball-tilt switches, secured within the housing. When the apparatus is moved the switches interrupt a current flow mimicking arcing events.

Abstract: A circuit breaker test device for testing a circuit breaker, and also for testing the branch circuit of which the circuit breaker is a part. The circuit breaker test device includes a switch that controllably short-circuits the branch circuit. A controller causes the switch to short circuit the branch circuit. A timer, responsive to operation of the controller, causes the switch to cease short-circuiting the branch circuit after a particular test time. An impedance value of the branch circuit is determined. The controller is enabled only if the impedance value is within predetermined limits. The timer is capable of establishing a variable test time.

Abstract: An injection test signal generator is incorporated into a circuit breaker. In this way, injection testing can be performed by causing the internal test signal generator to generate test signals and feed those signals to the trip circuitry of the circuit breaker. No independent injection test signal generator need be purchased or stored, or transported to the location of the circuit breaker and hardwired thereto. Various methods of communicating with the internal test signal generator can be implemented, including, for example, a standard interface, a wireless interface or a network interface. Dences can also be provided to selectively isolate the internal test signal generator from the trip circuitry to prevent accidental and erroneous breaker trips.

Abstract: A method for testing high-voltage alternating-current power switches in a synthetic test circuit has the step of connecting a high-voltage oscillating circuit in parallel to a test switch Bt in a time interval before the current zero of an interruptible high current, which is determined by a half-cycle duration (Th/2) of the oscillating current (ih) less the duration of equivalence (&Dgr;tse) of the sole flow of the oscillating current as sequential current in the test switch with a stress exerted upon the switch by the homogeneous current in a direct test circuit. The sequential-current flow duration of the equivalence results, at least approximately, from the comparison of the values of common physical stress parameters acting in the test switch during the test, on the one hand, in the synthetic test circuit and, on the other hand, in the direct test circuit.

Abstract: A residual current detection device comprising a plurality of resistive shunts for connection in respective ones of a plurality of lines though which current can flow to and from a load, and detector means sensitive to the voltage developed across each of the shunts to detect any imbalance between the currents flowing though the shunts.

Abstract: A system for arc detection testing using synthesized arcs is disclosed, which uses voltage and current waveform generators to generate an arc's analog form voltage and current waveform from a digital form of the arc's captured waveforms. A voltage waveform amplifier and a current waveform amplifier are included, with the outputs of the voltage and current waveform generators coupled to the inputs of the voltage and current waveform amplifiers, respectively. The outputs of the voltage and current waveform amplifiers are connected in circuit to a device under test to test the device's response to the waveforms. A method for testing a device's response to a simulated arcing condition is also disclosed. An electric arc's voltage and current waveforms are captured in digital form. Analog form voltage and current waveform are generated from the captured digital voltage and current waveforms.

Abstract: An annunciation system which will detect the majority of failed breakers and indicate to the consumer when a breaker needs to be replaced, but does not put the consumer in an emergency situation where critical loads have lost power. The annunication system provides a visible and audible indication of the failure of a breaker to trip either as a result of fault current conditions or a test of a ground fault or arc fault circuit.

Abstract: A tester for in situ testing of a plurality of circuit breakers having a range of rated currents and multiple trip functions, includes a plurality of power resistors of known impedance, an electronic switch associated with each power resistor connecting the resistor in series with the load terminal of the circuit breaker under test, and a controller that turns on a number of the switches selected to collectively draw through the associated power resistors a test current that is a function of the rated current and sufficient to trip the circuit breaker within a selected time window. Turn on of the electronic switches is also controlled to generate a current waveform appropriate for the trip function being tested. In a self test mode, the value of each of the power resistors is verified as being within limits.

Abstract: A sensor for a power distribution system includes: a conductor; a core proximate the conductor; and a reed switch adjacent the core, the reed switch in electrical communication with an electronic trip unit. A power distribution system includes: an upstream circuit breaker including an electronic trip unit; a downstream circuit breaker in electrical communication with the upstream circuit breaker; a first sensor positioned downstream from the downstream circuit breaker, the first sensor includes: a conductor in electrical communication with the downstream circuit breaker; a core located proximate the conductor; and a reed switch adjacent the core, the reed switch in electrical communication with the electronic trip unit.

Abstract: A current transducer system for measuring AC current in a high-voltage main circuit having a circuit breaker and a disconnecting switch in an integrated gas-insulated switchgear. The system comprises a current sensor for detecting the AC current and outputting an analog electric signal representing the AC current, the current sensor disposed near the circuit breaker. The system further comprises a sensor unit including an analog-to-digital converter for converting the analog electric signal to a digital electric signal, and an electric-to-optic converter for converting the digital electric signal to a digital optic signal, the sensor unit disposed near the circuit breaker. The system further comprises optic transmission means for transmitting the digital optic signal.

Abstract: The aim of the invention is to improve the interrupting capacity of a vacuum switch, to achieve this, the contact parts (4, 5) that can be displaced in relation to each other are separated at a variable speed. Separation takes place in such a way that during a predetermined time period a predetermined distance between the contacts is not exceeded. To prevent said predetermined distance from being exceeded, a braking element is allocated to the vacuum circuit breaker.

Abstract: A high-voltage oscillating circuit (I) is connected in parallel with an auxiliary circuit-breaker (Ba) by firing a switching spark gap (SGhv) and the oscillating current (ihv) is superimposed on the high-current (ihc) with opposite polarity just before the high-current zero crossing. The spark gap (SGhc) is fired at the artificial current zero, causing: short-circuiting of the high-current source (a), series connection of the high-voltage oscillating circuit with the test circuit-breaker (Bt), oscillating current from the auxiliary circuit-breaker is transferred with constant parameters to the test circuit-breaker there—in following the eliminated high current. Transient high voltage follows the zero crossing of the synthetic current continuously.

Abstract: A tester for in situ testing of a plurality of circuit breakers having a range of rated currents and multiple trip functions, includes a plurality of power resistors of known impedance, an electronic switch associated with each power resistor connecting the resistor in series with the load terminal of the circuit breaker under test, and a controller that turns on a number of the switches selected to collectively draw through the associated power resistors a test current that is a function of the rated current and sufficient to trip the circuit breaker within a selected time window. Turn on of the electronic switches is also controlled to generate a current waveform appropriate for the trip function being tested. In a self test mode, the value of each of the power resistors is verified as being within limits.