Abstract: A circuit breaker testing apparatus includes an electrical circuit, an adjustable inductor connected in the circuit and a transducer for sensing current flow in the circuit. The circuit has leads terminated by electrical connectors for connection to terminals of a circuit breaker for providing a source of electrical power to circuit from the circuit breaker. The inductor is adapted to produce an adjustable electrical load on the circuit breaker. The testing apparatus also includes an indicator connected to the transducer for producing a reading of the magnitude of current flow in the circuit and for displaying and holding the reading of the highest magnitude of current flow reached in the circuit and thereby the magnitude of current flow at which the circuit breaker is tripped by the adjustment of the electrical load on the circuit breaker.

Abstract: The present invention is substantially an indicator cap which is removably attachable to a prior art plug-in type fuse, and the cap having an indicator light for signaling that a fuse has blown so as to notify a user of the blown condition of the fuse. Furthermore, we provide unique circuitry which in combination with the existing circuitry provides unusual results, and we also provide a method of use therefore.

Abstract: A power controller (10) for supplying power to a power distribution network (N) in which power from a polyphase source (G) is routed to using equipment (E) connected to the network through the power controller. A plurality of solid-state power devices (82) switch each separate phase of the polyphase power to the equipment. A firing circuit (14) controls gating of the switches to route the power. Fuses (F) are connected between the switches and the using equipment to interrupt power flow to the equipment if excessive current begins to be drawn. A con, roller (20) controls a shutdown sequence employed by the controller to eliminate current spiking at shutdown. The various components are housed in an enclosure (22) which includes a mounting structure (56) for mounting the aforesaid components. A cooling system (26) employs a fan (88) for directing air flow through the mounting structure to cool the components.

Abstract: A resettable, latching indicator is described. The indicator has a pair of electrical terminals through which it connects to the circuitry whose state is being indicated. The device includes an electromagnetic coil with a first lead connected to a first terminal of the device and a second lead connected to a first contact within the device. A second contact within the device is connected to the second indicator terminal, completing the circuit within the device. In a preferred embodiment, the device is arranged as a fuse state indicator with the device terminals connected in parallel with a fuse. Before fuse blow, an internal electrical contact is formed as the first and second contacts are closed an abutment formed on a spring-biased indicator flag. When the fuse blows, current passes through the coil, thus creating a magnetic field. The field moves a spring-biased armature having a catch which normally retains the indicator flag in a non-indicating position.

Abstract: A drive circuit fault detection device comprising a discriminating circuit generating a digital signal, the level of which indicates a fault; and an identifying circuit generating a binary-coded signal indicating the type of fault, i.e. ground shorting of the drive circuit or an open load. The discriminating circuit comprises a resistive network connected to the output of the drive circuit, for generating a voltage indicating correct connection of the load or a fault on the drive circuit and a comparator for comparing the generated voltage with a reference voltage and supplying the digital signal at its output. The identifying circuit comprises a current mirror circuit generating an output voltage having two different logic levels in the event of short circuiting or an open load, respectively, and a combination circuit for generating the binary-coded output signal.

Abstract: A circuit configuration for a signalling device in circuit breaker units, in particular in power circuit breakers, which have an electronic tripping device and which become effective in the event of a fault in an electrical system to be protected, whereby the electronic tripping device includes a microcontroller which performs a fault evaluation, and for each type of fault makes available an output pin, from which the corresponding fault signal is amplified and transmitted to an electrical relay. The fault signal (FM, FM1 . . . FMn) is transmitted to the circuit configuration (SA, SA1 . . . SAn), and by means of logic operation with the action of a static standard signal and of a clock pulse signal (Clock Pulse) acts on the electrical relay, which is realized in the form of a bistable relay (RB, RB1 . . . RBn) the contact system of which corresponds to a make function or a break function, depending on the signal status of the standard signal.

Abstract: A device for measuring circuit breaker wear by integrating the square of the current to be interrupted, said circuit breaker including a control that is actuated by a trip coil. The device includes a timing delay circuit that is actuated by a signal corresponding to a change in the driven or non-drive state of the trip coil, the timing delay circuit causing integration to begin after time has elapsed that is equal to the mechanical delay of the circuit breaker, which mechanical delay is a previously-measured data item. The device further includes a circuit that delivers a signal proportional to the current carried by the circuit breaker, a circuit that squares the signal, and that applies said square to the integrator, said integration being performed for a given length of time that is longer than the maximum arcing time of the circuit breaker, which maximum arcing time is likewise a previously measured data item, the result of the integration being applied to a summing circuit.

Abstract: An electrically powered annunciating system, for use in electrical panel boxes, having a sensing circuit including a first acoustical transducer to transmit a sonic signal to an annunciating circuit having a second acoustical transducer at a spaced distance from the first transducer to operate the annunciating circuit responsive to a sonic signal received from the first transducer. The sensing circuit powers the first acoustical transducer to produce a sonic signal responsive to a sensed electrical event such as termination of power to an electrical component. The annunciating circuit includes a tuned amplifier for signal purification and amplification, a time delay integrator to prevent accidental circuit operation caused by noise and an annunciator and a communication interface activated responsive to a sonic signal received by the second transducer.

Abstract: A circuit breaker 10 includes a housing and an operating mechanism 12 contained within the housing. An indicating arrangement is carried by the operating mechanism 12 and is displaceable relative to the housing under the action of the operating mechanism 12 for indicating the status of the operating mechanism 12.

Abstract: There is provided a microcontroller for controlling the activation of a hopper, bowl feeder, and linear feeder. There is further provided a blown fuse circuit which indicates that a fuse has blown for the various components of the part feeder system as well as preventing machines at the load from being powered should the fuse blow.

Abstract: A fault control apparatus is disclosed having elements that provide for an easily reconfigurable fault response. When the fault detection circuit signals that a fault has occurred, an alarm is triggered, switching means are automatically set to their fault positions, and a control output circuit is activated. The flexibility of fault response is made possible by the use of a matrix of switched connections to preset the fault positions of the relays. Additional flexibility is provided by providing an adjustable level for the control output.

Abstract: In a circuit interrupter which has multiple electronic trip circuits, such as ground fault and arcing fault trip circuits, indicators such as LED's produce an indication of the cause of the trip. The trip signals are latched to provide a continuing trip indication and ORed to actuate the trip device. In one embodiment SCR's connected in series with the indicator LED's serve as the latches and are connected in parallel to the trip device to provide the OR function. In other embodiments, flip-flops serve as the latches. In one such embodiment, the indicator LED's are connected from the respective flip-flops in parallel to the trip device to provide the OR function. In another such embodiment the flip-flops actuate the trip device and turn on switches actuating the LED's These switches energizing the cause of trip LED's are disabled until the contacts open to assure operation of the trip device.

Abstract: The present invention provides a low burden visual POWER ON indicator for a self-powered electrical circuit protection device. The visual indicator includes a current transformer for producing an induced current in direct proportion to the current supplied to an electrical device protected by the protection device. The induced current is summed and rectified. An energy accumulator stores a predetermined voltage required to operate the protection device. The stored voltage is controlled by an accumulation switch which in turn is controlled by a hysteresis control circuit. The hysteresis control circuit includes an operational amplifier which is biased by a stable reference voltage. When the voltage on the energy accumulator is equal to the stable reference voltage the operational amplifier produces a HIGH output signal. When the voltage on the energy accumulator is less than the stable reference voltage the operational amplifier produces a LOW output signal.

Abstract: A resistance measuring circuit (10) generates a predetermined reference voltage and impresses that reference voltage across a squib detonation device (12). The resulting current flowing through the squib is mirrored by a current mirror (42,52,54) for providing multiple mirrored currents. The mirrored currents are compared to known current sources (58,60). The output signals go high or low depending on whether the mirrored currents are greater than or less than the fixed current sources. The output signals provide an indication as to whether the measured squib resistance is within a specified resistance range. The current sources may be precisely matched to maintain high accuracy in measuring the resistance.

Abstract: A method and system are provided for monitoring the pressure of gas in a gas filled circuit breaker container based on a temperature compensated gas pressure signal which is compared with a signal representing a desired gas pressure in the container to provide a signal indicating a gas leak when the actual pressure is less than the desired pressure. In addition to identifying a gas leak, the method and system is operable to deactivate the circuit breaker when the actual pressure decreases below a predetermined low pressure, to determine the gas leak rate and to deactivate the circuit breaker if the leak rate is greater than a predetermined acceptable rate and, otherwise, to determine the time required for the pressure to decrease to the unacceptable low pressure, and to activate an alarm, visual display and/or recording of information in response to certain detected conditions with respect to the gas pressure.

Abstract: Apparatus for generating alarms for a group of circuit interrupters, especially those which respond to arcing faults, includes a device associated with each circuit interrupter providing an indication of a tripped condition and a common alarm generator which generates an alarm when any one, or at least any one of a number of selected circuit interrupters, is in the tripped condition. In one embodiment of the invention, switches indicating that associated circuit interrupters are tripped generate auxiliary trip signals on a common alarm bus. The auxiliary trip signals are latched by a latch on the common alarm bus which energizes a relay to activate a local and/or remote alarm. The latch is reset by a switch on the load center door. In another embodiment of the invention, an IR beam is blocked from reaching a photo-detector whenever a circuit interrupter handle is in the tripped position which also results in energization of a relay to actuate the common alarm.

Abstract: A circuit which gives a continuous voltage output indication of whether a contact is open or closed. The circuit senses the voltage across the contact to detect whether the contact is open or closed. When there is a significant voltage, the circuit indicates that the contact is open. When the voltage is negligible, the circuit indicates that the contact is closed. Alternatively, the current through the contact can be sensed to provide an indication of whether the contact is conducting or not. The circuit can be used to indicate the welding close of a relay contact in which case power to the load can be turned off or the contact can be opened by other than normal corrective actions. One application is to discontinue closing movement of a garage door when the motor relay switch does not open as desired, but there are innumerable other applications.

Abstract: Transient voltage surge suppression (TVSS) meter adapter status indication perceptible by a nearby observer. When TVSS over-voltage protective means is on-line, a visible and/or audible signal is generated within the meter adapter housing and is transmitted to the exterior. Light emitted by an indicating lamp connected in series with the over-voltage protective element is transmitted to the exterior by means of a translucent rod to which the lamp is juxtaposed extending through the meter adapter housing wall and terminating just outside. Sound emitted by a buzzer similarly located is transmitted through the housing wall upon demand of an an observer outside, who actuates a normally open switch in series with the buzzer by juxtaposing a small magnet against the housing wall.

Abstract: A dynamic fuse testing device includes an elongated handle, a head pivotally mounted to the handle, a fastener for tightening the head relative to the handle to place the head and handle at a desired angular position relative to one another, a pair of elongated electrically conductive test probes for contacting opposite ends of a fuse, a pair of mounting members attached in spaced relation to one another on the head, the mounting members having respective outer ends mounting the respective probes, one of the mounting members being stationarily mounted on the head and the other of the mounting member being rotatably mounted on the head such that its outer end is pivotally movable toward and away from the outer end of the one mounting member for adjusting the distance between the probes to accommodate fuses of different sizes, and a lamp and battery on the head connected in series with the probes such that the lamp is illuminated by contact of the probes with a properly functioning fuse.

Abstract: A circuit breaker arranged with overload sensing, switches and LED indicators. Provided is a green LED (42) which when lit indicates that the circuit is blown and so the electrical wires from the breaker are not powered--the wires are "dead"; a red LED is also provided to indicate, when lit, that the electrical wires are powered or "live", in addition there is an amber third LED (52) which, when lit, indicates that a short circuit overload is still connected to the breaker output terminals.

Abstract: A fuse blowout detector circuit wherein the primary side of an insulated signal coupler, such as a photocoupler, is connected in parallel with a series circuit connection of a power supply and a fuse, whereby a fuse blowout detection signal is output from the secondary side of the signal coupler, independently of the ON/OFF state of the switch, when the fuse is blown.

Abstract: A status indicator for monitoring a fuse or a circuit breaker, including optically isolated triggering and alarm circuits which can be integrated into a fuse holder or circuit breaker housing. More particularly, a status indicator having an LED connected in series with a fuse or circuit breaker across a power source, and a phototransistor arrangement, connected across the power source, in series with an alarm circuit. The arrangement is configured so that as long as current flows through the fuse or circuit breaker, the LED produces light which causes the phototransistor to be maintained in a non-conducting state, and the status indicator to remain in a non-alarm state. Upon failure of the fuse or circuit breaker, current flow to the LED is interrupted, resulting in the phototransistor being biased into a conductive state, and the alarm circuit being activated.

Abstract: A fuse checker particularly adapted for use with miniature, plug-in fuses for testing the fuses while the fuses are in operative position in an electrical circuit. The checker includes a housing from which extend a pair of parallel contact points adapted for engagement with terminal tabs that lie within terminal access openings in a fuse housing. A ground lead is provided for completing the circuit, which includes a pair of light emitting diodes that have their lenses positioned to form part of the surface of a checker housing. A separate, current limiting resistor is applied between a respective LED and one of the contact points and the ground lead. The checker housing can be a hollow structure or it can be solid, to fully encapsulate the circuit elements that are positioned within the housing.

Abstract: A circuit for the detection of a fuse with oxide vertical fusing has another fuse that is of the same type but cannot be blown and, in parallel with each of the fuses, a voltage reference circuit. The output of each of the voltage reference circuits is an input of a differential comparator. This differential comparator is preferably provided with a voltage reference circuit that is independent of the supply voltage Vcc.

Abstract: In a switch with pre-alarm means having level adjusting apparatus (105a) of the pre-alarming and an indicator (103) for showing that value of current flowing on a load corresponds to the pre-alarm level, the level adjusting apparatus (105a) is adjusted with monitoring the indicator (103). When the indicator (103) is lighted, the value shown by level indicator (105b) of the level adjusting apparatus (105a) corresponds to actual value of the current flowing on the load at that time.

Abstract: A portable field tester for a circuit breaker having an electronic trip unit includes a ribbon cable having a connector plug for making connection to a restraint plug socket of the trip unit. The tester has a parallel connector in which the breaker rating plug may be inserted. A battery source is included and a battery fail LED is illuminated if the source voltage falls below a certain level. A voltage regulator and a plurality of voltage dividers develop reference test voltages for application to the breaker trip unit via the connectors and cable. Switches selectively disable a ground fault test circuit in the breaker during primary injection testing. A pair of resistors are connected via the cable and connectors for rapidly discharging the breaker memory circuits after each test.

Abstract: The operation and functioning of various elements in a circuit breaker panel assembly are monitored and tested using a permanently installed or a portable test module that can be plugged into a plug-in jack on the housing of the circuit breaker panel assembly. The test module includes readout elements, data recording elements as well as telemetry networks for relaying data to a central station where such data can be reduced, recorded and analyzed by experts. The circuit breaker panel can include a voltage surge and transient protection network. A method of monitoring and testing is also disclosed.

Abstract: An alarm circuit is provided which takes the place of auxiliary contacts that are generally used in association with circuit breakers or fuses to provide an alarm warning in the event that the circuit breaker or fuse in series with a load has opened for any reason. The alarm circuit is provided with a high resistance resistor that is connected to the load end of the circuit breaker, and at the other end of the resistor to a high gain amplifier or solid state switch. The output of the high gain amplifier is connected to a remote signal relay, which may be DC relay or an AC relay. The arrangement is such that the high gain amplifier becomes conductive in the event that the circuit breaker opens, thereby causing an alarm indication. Indicators are associated with the circuits, including an LED to provide a local signal indicative of the fact that the relay has changed its state. A remote alarm circuit is driven by the change of state of the remote signal delay.

Abstract: Low voltage electric switchgear equipment includes a central processor unit electrically interconnected with electronic main and branch circuit interrupters within the same enclosure and used within a multi-phase power distribution circuit. A terminal connector block is connected by cable with each of the electronic trip units within the branch circuit interrupters to provide communications between the branch circuit interrupters and the main circuit interrupter for continuously updating the status of the branch circuit interrupters and their associated electrical equipment. An operating program within the central processor unit determines whether unauthorized changes to the setpoints stored within individual branch circuit interrupters have occurred and immediately provides indication of such changes.

Abstract: An alarm assembly for use with a circuit breaker is provided. The assembly is used with the flux shunt trip device of the circuit breaker. The flux shunt trip device has a plunger which moves from a retracted position to an extended position to interrupt current through the circuit breaker upon a predetermined condition. The assembly includes an actuating member mounted in engageable relationship with the plunger so that when the plunger moves to its extended position, the actuating member moves to an actuated position. In the actuated position, the actuating member contacts a switch mechanism to actuate a switch which may be connected to an alarm or light indicator to identify that the circuit breaker has tripped. The actuating member remains in its actuated position until it is manually reset. A mechanism is provided for reset of the device.

Abstract: A neutral circuit current monitoring device detects at least one current level, which includes harmonic currents, flowing in a neutral circuit of a power distribution system such that preliminary warnings can be given to personnel operating the system before serious overload problems exist. Warnings can be given via audible and/or visual alarms and/or by electrical contacts which can be used to operate auxiliary devices. Preferably, two current levels defined by interchangeable secondary fuses within the monitoring circuit are detected with a first or low current level in the neutral circuit being calculated to also indirectly monitor for overheating of the distribution transformer caused mainly by circulating third harmonic currents in the transformer primary. The low current level permits personnel to investigate and correct a developing problem before it occurs. Preferably, a second or high current level of the current sensor can be set at a value less than 100% of the phase current rating.

Abstract: A device for testing support equipment for a power circuit breaker, including a breaker simulator for simulating a power circuit breaker, a connector for connecting the breaker simulator to a breaker control panel, and a switch for re-directing the functions of the breaker control panel to the simulator.

Abstract: A fuse and circuit testing apparatus providing a fuse adapter for each of a multiplicity of fuses and accessory circuits, the adapter inserted into a receptacle and carrying the fuse, the circuit at one terminal of each fuse being isolated for selector switch continuity through either the accessory or a continuity testing circuit.

Abstract: The open and closed conditions of the contacts within industrial-rated circuit breakers is externally ascertained by means of an auxiliary switch-contact position verifier accessory. A viewing aperture in the circuit breaker accessory cover provides visual access to a color-coded shutter that forms part of the auxiliary switch accessory and operates off the circuit breaker crossbar assembly. In the event that the circuit breaker contacts remain closed when the circuit breaker operating handle is moved to the OFF position, the colored indicia verifies the actual condition of the circuit breaker contacts.

Abstract: A fused cutout for a power distribution system, which cutout includes an insulating member (2) having two opposed ends and a recess located between the two opposed ends, a fuse (12) defining a current path and having an element for interrupting the current path when current flowing through the path exceeds a selected value, a first conductive support structure (6) connected at a first end of the insulating member (2), conductively connected to a first end of the current path and connectable to a source of electrical power (14), a second conductive support structure (8) connected at a second end of the insulating member (2), conductively connected to a second end of the current path and connectable to a consumer of electrical power (16), each conductive support structure (6,8) producing an electric field when connected to the source of electrical power, and a mounting bracket assembly (4) for supporting the fused cutout and including a conductive member (30) secured in the recess of the insulating member (2).

Abstract: A circuit breaker assembly incorporating a light emitting diode as an indicator when an overload condition is present and the circuit has been blown and further wherein the assembly includes an integral, internally placed load in the form of a capacitance sufficient to energize the light emitting diode when the load normally present in the circuit has been removed. The capacitance is connected in series with the light emitting diode as well as an external ground contact for providing the ground return for energizing the light emitting diode.

Abstract: A plug-in surge suppressor module for insertion into a circuit breaker panel includes four stacks of metal oxide varistors (MOVs) arranged in a cloverleaf pattern on opposite sides of an elongated copper ground bus attached to one lead of each of the metal oxide varistors. The other leads of two of the stacks of metal oxide varistors are attached to a terminal of a U-shaped first resistive wire fuse, another terminal of which is connected to a first AC power line conductor. The other leads of the other two stacks of MOV's are attached to a terminal of a second U-shaped resistive wire fuse, another terminal of which is connected to a second AC power line conductor. A monitor circuit senses the presence of power and continuity of both fuses by pulsing a light emitting indicator diode every cycle of the AC line. A low frequency oscillator circuit produces slow blinking of the light emitting indicator diode which alerts an observer to replace te surge suppressor module if one of the fuses fails.

Abstract: Portable testing apparatus for low current circuit breakers which enables short circuit and constant current tests to be conducted at the breaker panel. A first container includes a parallel array of resistive loads each under control of a corresponding relay. Low voltage control circuitry is provided in a second container and permits variation of the load appearing in series with the circuit breaker under test. The short circuit test can be performed at the first container which operates at the line voltage.

Abstract: An alarm switch operating apparatus for operating a plurality of circuit breaker alarm switches wherein a circuit breaker crossbar is further rotated from a tripped position by a rotation of a latch through a latch receiver during a tripping operation such that an alarm switch actuator is operated by the crossbar and wherein because the insulating bar of the crossbar extends across the left and right poles of the circuit breaker, the plurality of alarm switches are easily provided without damaging the insulation of the alarm switches.

Abstract: A circuit breaker monitoring system for monitoring three-phase circuit breakers includes three channels that convert a respective phase current through a respective set of circuit breaker contacts into a sequence of digital signals each representative of an instantaneous value of current through the contacts. Each channel includes a transformer having a primary winding that receives current corresponding to that through the breaker contacts. A resistor across the secondary winding develops a voltage proportional to the current. An input buffer voltage follower couples this voltage to the input of a high-speed 12-bit bipolar analog-to-digital converter that provides the digital signals. A microprocessor coupled to a 12K RAM working memory, a 4K EPROM that may store breaker monitor software and a 2K E.sup.

Abstract: A three-condition constantly illuminated status indicator is provided in a circuit breaker to provide three luminesce displays indicating that the breaker is in the on, off or tripped condition. Associated electrical circuitry employs diode-steered capacitive charging elements for selective, common or simultaneous energization of a three-color light emitting diode display without acting as a bypass around the circuit breaker, thus eliminating shock hazard. Selective energization of the light emitting elements is achieved by auxiliary switching means operable to a plurality of switching conditions according to switching conditions of the circuit breaker. The capacitors serve as an impedance to current for the light emitting diodes, eliminating the need for ballasting resistors, resulting in a cooler operating, lower power consumption unit.

Abstract: A multiphase electric machine having a failed electrical component detector includes a rotating member and a plurality of electrical components carried by the rotating member and arranged in groups for conducting electrical current. A plurality of detectors is carried by the rotating member with each of the detectors responsive to one of the groups of electrical components for detecting component failures. A plurality of light emitting diodes are carried by the rotating member so as to be grouped into concentric circles according to electrical phase. Each of the light emitting diodes is responsive to one of the detectors such that a component failure, and the phase in which that failure occurs, can be observed by the naked eye. A stationary monitor is disposed about the rotating member and is responsive to the plurality of light emitting diodes for providing an indication of the number of component failures per phase.

Abstract: A circuit breaker signal for use with a circuit breaker having a switch lever assembly has a housing. An LED associated with each respective circuit breaker is mounted on the housing. A switch extending from the housing comes in contact with the switch lever assembly when the circuit breaker has been activated and activates the associated LED.

Abstract: An integrated protection unit is an electronic trip circuit breaker which includes basic overcurrent protection facility along with selective electrical accessories. A molded plastic accessory access cover secured to the integrated protection unit cover protects the accessory components contained within the integrated protection unit cover from the environment. A combined overcurrent trip actuator and multiple accessory unit can be field-installed within the integrated protection unit. The combined actuator-accessory unit includes electronic control circuitry for the accessories along with mechanical trip and reset interface components. Additionally, a bell alarm signal unit can be incorporated within the trip actuator and multiple accessory unit enclosure.

Abstract: In a solid state relay circuit using a power semiconductor as the output circuit switching device and having protection against current overload and short circuits, an indicator circuit for signaling that overload currents have occurred in the switching device comprising circuitry for sensing that current overload protection has occurred, and switching circuitry responsive to the sensing that current overload protection has occurred for operating a current overload indicator.

Abstract: A fuse status detection circuit for determining the conduction of fuses used in integrated circuits is disclosed based on a flip-flop circuit containing the fuses which is set to an initial state during operation.

Abstract: A fuse carrier comprises a plurality of sockets for reed-type fuses, each socket being provided with a pair of electrode clips adapted to provide support and electrical connection for each fuse. The electrode clips configured to accommodate a microlamp which is connected in parallel to the fuse. The lamp therefore illuminates whenever the fuse burns out.

Abstract: The invention is directed to a portable test device for an electronic trip unit which is electrically powered from the internal power supply of the trip unit being tested. The test unit utilizes three leads connected to the trip unit. One of the leads connects to the voltage source for the trip unit and another lead connects to the ground potential to acquire power from the test unit. The voltage is selectively adjusted within the test unit by resistors and a potentiometer to vary the input voltage which is to be carried by the third lead into the trip unit.

Abstract: A digital solid-state trip unit of an electrical circuit breaker is equipped with an electrical contact wear indicator enabling the degree of wear of these contacts to be known. Each time the circuit breaker performs a break, the microprocessor determines a contact wear value, in terms of the maximum value of the current broken. The correspondence between the wear value and the current broken is stored in a ROM memory and the successive wear values are added in a NOVRAM memory whose contents are representative of the degree of contact wear. These contents can be displayed to indicate to the user that the condition of the contacts has to be checked.

Abstract: A remote indicator for displaying the position of a power control switch whether or not power is applied to the switch. An auxiliary DC power supply provides a reference potential to a plurality of voltage dividers. One voltage divider provides a first reference potential to a comparator. A second voltage divider and the reference power supply are connected through the power control switch so that a second reference potential is applied to the comparator when the power switch is closed. Differences of the two reference potentials corresponding to the open and closed switch positions are sensed by the comparator and used to activate an indicator accordingly.