Patent Description:
A circuit breaker can be set in an open position and in a closed position. The circuit breaker may be a motor protective circuit breaker (in German Motorschutzschalter). Typically, a circuit breaker comprises an operating handle to manually set the circuit breaker in the open or the closed position. Additionally, the circuit breaker is configured to automatically set itself in the open position in case a current flowing through the circuit breaker is above a predetermined value for some time or in case of a short circuit. In the open position, no current flows through the circuit breaker. For example, the circuit breaker can be used for the protection of an electrical motor or another electrical load.

The circuit breaker comprises at least one switch. The circuit breaker may comprise an auxiliary switch that is coupled to the at least one switch of the circuit breaker and also changes its position in the case that the switch of the circuit breaker changes its position from open to closed or vice versa. A connection of the auxiliary switch to a control device may be used to provide information about the closed or open position of the circuit breaker to the control device.

Document <CIT> describes a magnetically driven trip mechanism for an overload relay. The overload relay includes a tripping actuator with a first magnet and a movable contact carrier with a second magnet. Moreover, the relay comprises a bimetallic thermal overload sensor that comprises a bimetal strip and a current carrying heater coil. The overload sensor is connected to the tripping actuator. The two magnets repel each other when the tripping actuator moves from an ON position to an OFF position.

Document <CIT> is related to an electromechanical switching device. A circuit breaker includes connecting terminals, a bimetal in the form of a line connection, a solenoid, a contact configuration with a fixed contact and a moving contact, a permanent magnet, an inductance sensor and a switch housing. The magnet and the inductance sensor are inside of the switch housing. The inductance sensor detects a magnetic field originating from the magnet. The magnet is in a fixed position to the inductance sensor. A movement of a drive clip changes a magnetic circuit and thus can be detected by the inductance sensor.

Document <CIT> refers to a module with life time control of an electromagnetic switch. An arrangement includes a switch and a communication module. A magnet is fixed on a bar of the switch. The bar with the magnet protrudes into the communication module. The position of the magnet can be detected by a sensor of the communication module.

It is an object to provide a circuit breaker and a method for operating a circuit breaker which can provide information about the status of the circuit breaker with high efficiency.

This object is achieved by the subject-matter of the independent claims. Further developments and embodiments are described in the dependent claims.

The definitions as described above also apply to the following description unless otherwise stated.

In an embodiment, a circuit breaker comprises a first and a second breaker terminal, a bimetal stripe, a first conduction line, a switch with a first and a second contact, a triggering device mechanically coupling the bimetal stripe to the switch, a magnet and a detection device. The first conduction line is electrically coupled to the first breaker terminal and to the first contact and is wound around the bimetal stripe. The magnet is connected to at least one of the bimetal stripe, the triggering device and the switch. The detection device comprises a magnetic field sensor for detecting a magnetic field of the magnet.

Advantageously, the magnetic field sensor of the detection device detects the magnetic field of the magnet. The bimetal stripe, the triggering device or the switch are mechanically moved parts of the circuit breaker. Since the magnet is connected to one of the mechanically moved parts of the circuit breaker, a position of the mechanically moved part is detected by the magnetic field sensor. Thus, the detection device is configured to determine information about a state of the circuit breaker. Thus, the state of the circuit breaker is detected by an electric method.

In an embodiment, the first conduction line includes a wire or a conducting stripe that is spiraled around the bimetal stripe. The wire or the conducting stripe are configured to generate heat in case of a current flow. The wire or the conducting stripe are a resistive heater.

In an embodiment, the triggering device sets the switch in an open position in case the bimetal stripe is heated above a predetermined temperature by current that flows through the first conduction line. The predetermined temperature may be set with a tolerance.

In a further development, the triggering device sets the switch in the open position in case a value of the current is higher than a first predetermined value of the current for a predetermined time.

In an embodiment, the triggering device converts the movement of a movable end of the bimetal stripe to a movement of an operating shaft of the switch.

In an embodiment, the magnetic field sensor comprises a magnetic resistance sensor.

In an embodiment, the magnetic resistance sensor is realized as one of an anisotropic magnetic resistance sensor (abbreviated as AMR), giant magnetic resistance sensor (abbreviated as GMR) and a tunneling magnetic resistance sensor (abbreviated as TMR).

In an embodiment, the magnetic field sensor comprises a Hall-effect sensor.

The magnetic field sensor may be realized as a linear position sensor or a rotary angular position sensor.

In an embodiment, the detection device converts a position information of the position of the magnet into a detection signal. The detection signal is an electrical detection signal.

In an embodiment, the detection device is configured to supply the detection signal representative of a position of at least one of the bimetal stripe, the triggering device and the switch (e.g. of the operating shaft of the switch, the contact bridge of the switch and/or the at least one movable contact of the switch).

In an embodiment, the detection signal may be realized as an analog signal. The analog signal is a function of the position of the magnet, e.g. a linear or a non-linear function.

In an embodiment, the detection signal may be realized as a digital signal. The digital signal may be a one bit signal; for example the detection signal indicates a tripped circuit breaker. Alternatively, the digital signal provides more than one bit. The digital signal may indicate the position of the magnet with a resolution of more than one bit.

In an embodiment, the detection signal is realized as a pulse-width modulated signal.

In an embodiment, the pulse-width modulated signal has a duty cycle. The duty cycle is a function of the position of the magnet, e.g. a linear or a non-linear function.

In an alternative embodiment, the detection signal is realized as an analog signal such as a <NUM> to <NUM> mA signal or a <NUM> to <NUM> V signal.

In an alternative embodiment, the detection signal is realized as a digital signal such as a bus signal.

In an embodiment, the detection signal is set in case a load is above a first threshold.

In an embodiment, the detection device converts the position information of the position of the magnet into a further detection signal. The further detection signal may be set in case the load is above a second threshold.

The load may be e.g. a value of the current flowing through the first conduction line, a value of the temperature of the bimetal stripe or a value of the position of the magnet. Values above <NUM>% indicate an overload. Values up to <NUM>% indicate a normal load. The first and the second threshold are different. The first and the second threshold may be e.g. at <NUM>% and <NUM>% of a nominal value or a continuous limit value of the current, the temperature or the position.

In an embodiment, the detection device comprises a control circuit and at least a first output terminal. The control circuit is connected to the magnetic field sensor and to the at least a first output terminal.

The control circuit may comprises a communication module.

In an embodiment, the circuit breaker comprises a first and a second housing. The first housing at least encloses the bimetal stripe, the first conduction line, the switch, the triggering device and the magnet.

In an embodiment, the second housing at least encloses the detection device.

The shape of the first housing may be adapted to the shape of the second housing.

The second housing may be formed such that it can be fixed at a side of the first housing. The first and the second housing may be interconnected.

In an embodiment, the circuit breaker comprises an operating handle that is configured to manually set the circuit breaker in an open or a closed position and is mechanically connected to the triggering device.

The operating handle may be intended for manual release. The operating handle may be implemented e.g. as a twist handle, a toggle switch or a push button.

In an embodiment, the switch comprises at least one fixed contact and at least one movable contact. A fixed contact may be named stationary contact. The at least one fixed contact is non-movable mounted in the first housing. The at least one movable contact is movable mounted in the first housing. The triggering device may be operatively connected to the at least one movable contact via the operating shaft of the switch.

In an embodiment, the first and the second contact of the switch are realized as a fixed contact and a movable contact.

The operating shaft of the switch is connected to the movable contact of the switch.

In an alternative embodiment, the first and the second contact of the switch are both realized as fixed contacts. The switch additionally comprises a first and a second movable contact. The switch comprises a contact bridge coupling the first to the second movable contact. The operating shaft of the switch is connected via the contact bridge to the first and the second movable contact.

In an embodiment, the triggering device performs opening and closure of the switch. The switch has a first and a second operating position which are implemented as open and closed position.

The triggering device may be realized as a tripping device, a switch mechanical system and/or an actuation device. The triggering device may comprise a spring.

In an embodiment, the circuit breaker is implemented as a thermal magnetic circuit breaker.

In an embodiment, a method for operating a circuit breaker comprises flowing a current from a first breaker terminal to a second breaker terminal via a first conduction line and a switch, heating a bimetal stripe by the first conduction line, moving a magnet as a function of the heat provided to the bimetal stripe and detecting a magnetic field of the magnet by a detection device comprising a magnetic field sensor. The conduction line is wound around the bimetal stripe. The bimetal stripe is mechanically coupled to the switch via a triggering device. The magnet is connected to at least one of the bimetal stripe, the triggering device and the switch.

Advantageously, the current that flows through the first conduction line results in a movement of the magnet and the movement is detected by the magnetic field sensor. Thus, the detection device is configured to gain information about the position of the circuit breaker.

The method for operating a circuit breaker may be implemented e.g. by the circuit breaker according to one of the examples described above.

In an example, the circuit breaker is configured for an overload indication with the magnetic field sensor such as an AMR sensor. The circuit breaker is able to provide an information about its overload situation. The detection and evaluation of the overload state of the circuit breaker can be implemented by the magnet and the magnetic field sensor. The magnet may be a permanent magnet. The magnet may be attached at a movable bridge of the triggering device. The movable bridge connects the three bimetal stripes to the further parts of the triggering device. The magnetic field sensor is attached such that it can detect the movement of the magnet and consequently also of the bridge of the triggering device.

The circuit breaker can be fabricated as motor-protection switch, overload protection switch or overload relay.

The detection device can be attached to the first housing and can also be detached. Thus, the magnetic field sensor is outside of the first housing and detects the movement of the magnet inside the first housing.

In an embodiment, the overload warning is evaluated in a control device and can be processed further. The control device may be realized as a programmable logic controller, abbreviated as PLC, in German speicherprogrammierbare Steuerung, abbreviated SPS. The overload warning can e.g. be forwarded via the control device and used for predictive maintenance applications. Furthermore, in case of overload, the control device can send a warning message to the circuit breaker to switch off the assigned contactor or load before the circuit breaker trips. This allows a selectable overload relay function (in German Uberlastrelaisfunktion; abbreviated ZMR function) to be implemented. Furthermore, in case of overload, the control device can send a switch off control signal to the assigned contactor of the circuit breaker before the circuit breaker trips.

To achieve that the ZMR function is independent of the control device, the control signal could possibly control a simple control module on the contactor and thus also realize the ZMR function.

The following description of figures of embodiments shall further illustrate and explain aspects of the circuit breaker. Parts and components with the same structure and the same effect, respectively, appear with equivalent reference symbols. Insofar as parts and components correspond to one another in terms of their function in different figures, the description thereof is not repeated for each of the following figures.

<FIG> shows a schematic of an example of a circuit breaker <NUM> having a first and a second breaker terminal <NUM>, <NUM>. For example, the first breaker terminal <NUM> can be connected to an electrical power source (not shown) and the second breaker terminal <NUM> can be connected to a motor (not shown). Moreover, the circuit breaker <NUM> comprises a bimetal stripe <NUM> and a first conduction line <NUM>. The first conduction line <NUM> is electrically connected to the first breaker terminal <NUM>. The first conduction line <NUM> is wound around the bimetal stripe <NUM>. The first conduction line <NUM> is coupled to the second breaker terminal <NUM> via a not-shown switch of the circuit breaker <NUM>. The bimetal stripe <NUM> has a fixed end <NUM> and a movable end <NUM>. The circuit breaker <NUM> comprises a magnet <NUM> that may be attached to the bimetal stripe <NUM>. The magnet <NUM> may be fixed at the movable end <NUM> of the bimetal stripe <NUM>.

Moreover, the circuit breaker <NUM> comprises a detection device <NUM> including a magnetic field sensor <NUM>. The magnetic field sensor <NUM> is arranged in the vicinity of the magnet <NUM>. The magnetic field sensor <NUM> is located in a magnetic field of the magnet <NUM>. The detection device <NUM> comprises a control circuit <NUM> that is connected to the magnetic field sensor <NUM>.

The control circuit <NUM> may be implemented as an application-specific integrated circuit, abbreviated as ASIC. The control circuit <NUM> may be realized as a microcontroller or microprocessor. The control circuit <NUM> may be fabricated as single chip solution. The control circuit <NUM> is connected on its output side to a first output terminal <NUM> of the detection device <NUM>. The detection device <NUM> comprises a first supply terminal <NUM> that may be assigned for receiving a supply voltage VDD. The supply voltage VDD may be a direct current voltage, abbreviated DC voltage. For example, the supply voltage VVD may have a value of <NUM> V. The detection device <NUM> includes a reference potential terminal <NUM>.

The first supply terminal <NUM> and the reference potential terminal <NUM> are connected to the control circuit <NUM>. Moreover, the first supply terminal <NUM> and the reference potential terminal <NUM> may be connected to the magnetic field sensor <NUM> by not-shown conduction lines. A smoothing capacitor <NUM> of the detection device <NUM> may be coupled between the first supply terminal <NUM> and the reference potential terminal <NUM>. The detection device <NUM> comprises a protection device <NUM> that is connected to the first supply terminal <NUM> and to an internal reference potential terminal <NUM>. The internal reference potential terminal <NUM> may be directly connected to the reference potential terminal <NUM>. The protection device <NUM> may be realized as a Zener diode or a bidirectional suppressor diode. The protection device <NUM> increases the electromagnetic compatibility (abbreviated as EMC) of the detection device <NUM>.

A second output terminal <NUM> of the detection device <NUM> is connected to the reference potential terminal <NUM>. A reference potential GND is provided at the reference potential terminal <NUM>. In <FIG>, a possible terminal assignment of the detection device <NUM> is illustrated.

In the case that the circuit breaker <NUM> is set in a closed position (which may be named conducting state), a current I flows through the first conduction line <NUM>. The current I results in an increase of the temperature of the conduction line <NUM> and thus of the bimetal stripe <NUM>. The increase of the temperature of the bimetal stripe <NUM> results in a movement of the movable end <NUM> of the bimetal stripe <NUM>. In the case that the current I is very low, this movement remains very low. Typically, the bimetal stripe <NUM> changes its bending when heated.

The magnetic field sensor <NUM> detects a magnetic field generated by the magnet <NUM>. The magnetic field sensor <NUM> may be realized as a magnetic resistance sensor such as an anisotropic magnetic resistance sensor, abbreviated as AMR sensor. The magnetic field sensor <NUM> generates a sensor signal SE1 that is provided to the control circuit <NUM>. The control circuit <NUM> generates a detection signal SD1 and provides it to the first output terminal <NUM>. The detection signal SD1 is an electrical detection signal. The detection signal SD1 may be realized as a pulse width modulated signal. A duty cycle of the pulse width signal depends on the sensor signal SE1 and thus depends on the position of the magnet <NUM>.

In case the current I changes the position of the magnet <NUM> via a temperature rise of the bimetal stripe <NUM>, the duty cycle of the detection signal SD1 is changed. The duty cycle of the detection signal SD1 represents the position of the magnet <NUM> and thus a temperature of the bimetal stripe <NUM>. <FIG> only shows a schematic of the circuit breaker <NUM>, wherein several parts of the circuit breaker <NUM> are omitted. In the example as shown in <FIG>, the circuit breaker <NUM> can switch and control one current path.

The control circuit <NUM> may evaluate the sensor signal SE1 regarding at least one of the following features:.

In an alternative embodiment, not shown, the detection device <NUM> comprises a voltage converter that converts the supply voltage VDD to a lower voltage (e.g. <NUM> Volt) that is provided to the control circuit <NUM> and/or to the magnetic field sensor <NUM>.

In an alternative embodiment, not shown, the detection device <NUM> comprises a relay or solid state contact that is connected on the output side to the first output terminal <NUM>. In this case, the output may not be realized as an "active output".

<FIG> shows a further example of the circuit breaker <NUM> that is a further development of the example shown in <FIG>. The circuit breaker <NUM> comprises a switch <NUM> having a first and a second contact <NUM>, <NUM>. The first contact of the switch <NUM> is coupled to the first conduction line <NUM>. The second contact <NUM> of the switch <NUM> is coupled to the second breaker terminal <NUM>. In a typical embodiment, the circuit breaker <NUM> comprises a coil <NUM> that is also included in the conduction path between the first breaker terminal <NUM> and the second breaker terminal <NUM>. For example, the coil <NUM> couples the first conduction line <NUM> to the switch <NUM>. Thus, the first breaker terminal <NUM> is electrically connected via a series circuit of the first conduction line <NUM>, the coil <NUM> and the switch <NUM> to the second breaker terminal <NUM>. However, the order of the elements - the first conduction line <NUM>, the coil <NUM> and the switch <NUM> - can be interchanged in this series connection.

Moreover, the circuit breaker <NUM> comprises a triggering device <NUM>. The movable end <NUM> of the bimetal stripe <NUM> is mechanically connected to the triggering device <NUM>. The triggering device <NUM> is mechanically connected to the switch <NUM>. For example, the switch <NUM> comprises an operating shaft <NUM> and at least one movable contact <NUM>. The triggering device <NUM> is mechanically coupled via the operating shaft <NUM> to the at least one movable contact <NUM>.

In the embodiment shown in <FIG> the switch <NUM> has a first and a second fixed contact. The first and the second contact <NUM>, <NUM> of the switch <NUM> are realized as the first and the second fixed contact. Moreover, the switch <NUM> comprises a first and a second movable contact <NUM>, <NUM> and a contact bridge <NUM> that connects the first movable contact <NUM> to the second movable contact <NUM>. In the case that the switch <NUM> is set in a closed position (which is a conducting state), the first contact <NUM> is in electrical contact to the first movable contact <NUM> and the second contact <NUM> is in electrical contact to the second movable contact <NUM>. In the case that the switch <NUM> is set in an open position, the first and the second contact <NUM>, <NUM> are separated from the first and the second movable contact <NUM>, <NUM>. The operating shaft <NUM> sets the switch <NUM> in the open and in the closed position. In the embodiment shown in <FIG> the magnet <NUM> is connected to the operating shaft <NUM>. The magnetic field sensor <NUM> is placed in the vicinity of the magnet <NUM>.

Moreover, the circuit breaker <NUM> comprises an operating handle <NUM> that is mechanically coupled to the triggering device <NUM>. A movement of the operating handle <NUM>, for example by an operator, can set the circuit breaker <NUM> from the open to the closed position or vice versa.

The current I flowing from the first breaker terminal <NUM> to the second breaker terminal <NUM> can generate a temperature rise of the bimetal stripe <NUM> that results in a triggering of the triggering device <NUM> such that the circuit breaker <NUM> is set in the open position. This is achieved by a movement of the operating shaft <NUM> that sets the switch <NUM> in the open position. Due to the mass of the bimetal stripe <NUM> and the time constants for heating of the bimetal stripe <NUM> a very short pulse in the current I does not result in a movement of the movable end <NUM> of the bimetal stripe <NUM> that triggers the triggering device <NUM>. However in case the current I is over a first predetermined value over a longer time (e.g. a predetermined time) the movement of the bimetal stripe <NUM> results in a movement of the operating shaft <NUM> which can be detected by the magnetic field sensor <NUM>. The movement of the operating shaft <NUM> results in triggering the circuit breaker <NUM>.

The coil <NUM> and the triggering device <NUM> are configured such that the current I above a second predetermined value instantly triggers the triggering device <NUM> such that the switch <NUM> is set in the open position. The coil <NUM> is designed for the triggering of the triggering device <NUM> in case of a short circuit. Thus, a short circuit protection is realized by the coil <NUM>.

In an example, the magnetic field sensor <NUM> detects whether the circuit breaker <NUM> is in the open or the closed position.

In an alternative embodiment, the magnet <NUM> is attached to a movable part of the triggering device <NUM>. This movable part is mechanically arranged between the bimetal stripe <NUM> and the operating shaft <NUM> of the switch <NUM>. The magnet <NUM> may be attached to such a movable part of the triggering device <NUM> that is moved as a reaction to the movement of the movable end <NUM> of the bimetal stripe <NUM> before the operating shaft <NUM> is moved for setting the switch from the closed to the open position. Thus, the magnetic field sensor <NUM> is able to detect the closed and the open position of the switch <NUM> and also intermediate states of the circuit breaker <NUM>. Thus, the magnetic field sensor <NUM> is configured to detect that the current I is in an interval below the first predetermined value. In this interval the circuit breaker <NUM> is still in a closed position. However, the detection device <NUM> is able to generate the detection signal SD1 with the information that the sensor signal SE1 rises from a normal value to an interval that is close to the first predetermined value.

Thus, the detection device <NUM> can be used for providing a warning message.

In an embodiment, the magnet <NUM> and the magnetic field sensor <NUM> are located as shown in <FIG> or <FIG> or as described above and detect the movement of the bimetal stripe <NUM> and/or of the movable part of the triggering device <NUM> and/or of a movable bridge of the triggering device <NUM>. The circuit breaker <NUM> may comprise a further magnet and the detection device <NUM> may comprise a further magnetic field sensor. The further magnet and the further magnetic field sensor detect whether the circuit breaker <NUM> is in the open or the closed position and may be located e.g. as shown in <FIG>.

<FIG> shows a further example of the circuit breaker <NUM> which is a further development of the examples shown in <FIG> and <FIG>. The circuit breaker <NUM> comprises a first and a second housing <NUM>, <NUM>. The second housing <NUM> encloses the detection device <NUM>. The first housing <NUM> encloses the bimetal stripe <NUM>, the first conduction line <NUM>, the switch <NUM>, the triggering device <NUM> and the magnet <NUM>. The operating handle <NUM> is located at a front side of the first housing <NUM>. The operating handle <NUM> is connected via a not-shown shaft through an opening of the first housing <NUM> to the triggering device <NUM>. The first and the second breaker terminal <NUM>, <NUM> are located such that they can be contacted from the outside. Moreover, the circuit breaker <NUM> comprises a third to a sixth breaker terminal <NUM> to <NUM>. The additional breaker terminals <NUM> to <NUM> are also located at the surface of the first housing <NUM> such that they can be contacted from the outside. The second and the first housing <NUM>, <NUM> are formed such that the second housing <NUM> can easily be attached to the first housing <NUM>.

<FIG> shows an example of the magnetic field sensor <NUM> which can be used in the circuit breaker <NUM> as shown in <FIG>. Such a magnetic field sensor <NUM> may be provided for example by Murata Manufacturing Company, Japan. In <FIG>, a conventional magnetic field sensor <NUM> is explained. The magnetic field sensor <NUM> is implemented as a magnetic resistance sensor. The magnetic field sensor <NUM> is realized as anisotropic magnetic resistance sensor, abbreviated as AMR. Thus, the magnetic field sensor <NUM> comprises a first to a fourth resistor <NUM> to <NUM> that are connected to each other in the form of a Wheatstone bridge. The first and the second resistor <NUM>, <NUM> form a first series circuit and the third and the fourth resistor <NUM>, <NUM> form a second series circuit. Both series circuits are connected between a supply terminal <NUM> and the internal reference potential terminal <NUM>. A first tap <NUM> is formed between the first and the second resistor <NUM>, <NUM>. A second tap <NUM> is formed between the third and the fourth resistor <NUM>, <NUM>. The first and the second tap <NUM>, <NUM> are connected to a sensor circuit <NUM> that may be fabricated as integrated circuit. The sensor circuit <NUM> may be realized as a complementary metal oxide semiconductor circuit, abbreviated as CMOS circuit.

The sensor circuit <NUM> comprises an amplifier <NUM> having two inputs that are connected to the first and the second tap <NUM>, <NUM>. The output of the amplifier <NUM> is coupled to a signal output <NUM> of the magnetic field sensor <NUM>. The supply voltage terminal <NUM> of the detection device <NUM> may be coupled to the supply terminal <NUM>, for example via a switch <NUM>. The sensor circuit <NUM> may comprise a latching circuit <NUM> and a further circuit <NUM> that couple the output of the amplifier <NUM> to the signal output <NUM> of the magnetic field sensor <NUM>. A sampling circuit <NUM> of the sensor circuit <NUM> is connected to a terminal of the switch <NUM>, to the supply voltage terminal <NUM> and to an input of the latching circuit <NUM>.

Advantageously, the magnetic field sensor <NUM> realized as AMR sensor has a small sensor package, a high sensitivity and a high reliability. The magnetic field sensor <NUM> may be provided in a Small Outline Transistor package, abbreviated SOT package.

<FIG> shows an example of a characteristic of the magnetic field sensor <NUM> as shown in <FIG>. In <FIG>, the output voltage VOUT is shown as a function of a magnetic field strength Hy that is measured in the y-direction. Moreover, an auxiliary magnetic field Hx is applied to the magnetic field sensor <NUM> in the x-direction. The magnetic field sensor <NUM> may be configured to detect linear movements of the magnet <NUM>.

In an alternative embodiment, not shown, the magnetic field sensor <NUM> can be realized using another sensor, such as for example a Hall-effect sensor.

<FIG> shows an example of an arrangement <NUM> comprising the circuit breaker <NUM> as explained in the figures above. The arrangement <NUM> additionally comprises a control device <NUM>. The control device <NUM> may be realized as a programmable logic controller or memory programmable controller, abbreviated as PLC. The control device <NUM> comprises an input terminal <NUM> connected to the first output terminal <NUM> of the circuit breaker <NUM>. Moreover, the control device <NUM> comprises a supply voltage terminal <NUM> and a reference potential terminal <NUM>. The supply voltage terminal <NUM> is connected via connection lines to the supply terminal <NUM> of the circuit breaker <NUM> and to a non-shown supply voltage source. The reference potential terminal <NUM> of the control device <NUM> is connected via connection lines to a ground potential terminal and to the reference potential terminals <NUM>, <NUM> of the detection device <NUM>.

The input terminal <NUM> is a digital input. The input terminal <NUM> receives the detection signal SD1. The control device <NUM> is configured to evaluate the pulse width modulated detection signal SD1. The detection signal SD1 has a low frequency. Thus, the control device <NUM> is able to evaluate the detection signal SD1. Due to the low frequency of the detection signal SD1, the timing in the control device <NUM> is not critical. Advantageously, the circuit breaker <NUM> can communicate the detection signal SD1 to the control device <NUM>. Thus, an increase of the current I can be detected by the detection device <NUM> and can be provided to the control device <NUM>. Thus, the control device <NUM> or a further controller connected to the control device <NUM> can make amendments in an apparatus connected to this arrangement <NUM>, for example by amending a condition of a motor connected to the circuit breaker <NUM>. Thus, the arrangement <NUM> can react on a rise of the current I before the triggering device <NUM> of the circuit breaker <NUM> interrupts the flow of the current I.

The control device <NUM> processes the detection signal SD1 that indicates an overload warning and may provide a warning information, a maintenance information and/or a switch off signal. The ZMR function could be realized also with a standard circuit breaker and a contactor (which may be named e.g. DILM contactor). The control device <NUM> may comprise a standard interface connected to the input terminal <NUM>. A software of the control device <NUM> is configured to evaluate the detection signal SD1, especially a pulse-width modulated detection signal SD1.

<FIG> shows a further example of the circuit breaker <NUM> that is a further development of the examples shown above. As explained above, the circuit breaker <NUM> may comprise a first to a sixth breaker terminal <NUM>, <NUM>, <NUM> to <NUM>. Thus, the circuit breaker <NUM> additionally comprises a further and an additional bimetal stripe <NUM>, <NUM>, a second and a third conduction line <NUM>, <NUM> and a further and an additional switch <NUM>, <NUM>. The third breaker terminal <NUM> is coupled via the second condition line <NUM> and the further switch <NUM> to the fourth breaker terminal <NUM>. Correspondingly, the fifth breaker terminal <NUM> is coupled via the third conduction line <NUM> and the additional switch <NUM> to the sixth breaker terminal <NUM>.

The triggering device <NUM> is connected on its input side not only to the bimetal stripe <NUM>, but also to the further and the additional bimetal stripe <NUM>, <NUM>. On its output side the triggering device <NUM> is connected not only to the switch <NUM> but also to the additional and the further switch <NUM>, <NUM>. To reduce the complexity of <FIG>, further parts of the circuit breaker <NUM> such as the three coils, the operating handle <NUM> and most parts of the triggering device <NUM> are omitted.

The three bimetal stripes <NUM>, <NUM>, <NUM> are connected in an OR combination by the triggering device <NUM>. Thus, a movement of one of the three bimetal stripes <NUM>, <NUM>, <NUM> is sufficient to trigger the triggering device <NUM> such that the triggering device <NUM> sets the three switches <NUM>, <NUM>, <NUM> in an open position. The magnet <NUM> may be fixed at the triggering device <NUM>.

The triggering device <NUM> comprises a movable bridge <NUM>. The movable bridge <NUM> connects the three bimetal stripes <NUM>, <NUM>, <NUM>. The movable bridge <NUM> performs an OR-function of the movement of the three bimetal stripes <NUM>, <NUM>, <NUM>. The movable bridge <NUM> is coupled via other parts (not shown) of the triggering device <NUM> to the operating shafts of the three switches <NUM>, <NUM>, <NUM>. Thus, the circuit breaker <NUM> includes three current paths which are connected in parallel and can be switched on and off by the three switches <NUM>. The three switches <NUM> are simultaneously operated.

In <FIG>, the three bimetal stripes <NUM>, <NUM>, <NUM> are differently bended. A small force F is exerted on the movable bridge <NUM>. Thus, the bimetal stripe which has the highest temperature of the three bimetal stripes <NUM>, <NUM>, <NUM> determines the position of the movable bridge <NUM> (in <FIG>, the bimetal stripes <NUM> and <NUM> determine the position of the movable bridge <NUM>). The magnet <NUM> is fixed at the movable bridge <NUM>. Thus, the position of the bimetal stripe which has the highest temperature is detected by the detection device <NUM>.

The motor-protective circuit breaker <NUM> protects motor or transformer loads against overload and short circuit. The operating principle for overload detection is based on the mechanical force effect of bimetals. Due to the excessive current, the bimetals in the circuit breaker <NUM> (three pieces due to three-phases) are moved mechanically, which causes the circuit breaker <NUM> to trip. After the mechanical overload tripping, the main current paths are separated by the circuit breaker <NUM> and thus e.g. the motor load is switched off. Advantageously, the overload status and/or the time to tripping of the circuit breaker <NUM> can be detected with the detection device <NUM>. The detection device <NUM> alone or the detection device <NUM> in combination with the control device <NUM> may determine at least one of:.

The circuit breaker <NUM> provides an information about the overload situation using the detection device <NUM>. The detection and evaluation of the overload situation is achieved by the magnet <NUM> that is a permanent magnet and the AMR sensor <NUM>. The magnet <NUM> may be fixed at the movable bridge <NUM> that connects the three bimetal stripes <NUM>, <NUM>, <NUM> and is part of the triggering device <NUM>. The magnetic field sensor <NUM> (e.g. an AMR sensor) is located in the second housing <NUM> that may optionally include further circuit parts. The magnetic field sensor <NUM> is located such that it senses the movement of the magnet <NUM> and thus also the movement of the movable bridge <NUM>. The movement per time can be related to the overload state of the circuit breaker <NUM> (e.g. by the detection device <NUM> itself or by the control device <NUM>) and thus realizes a measurement.

The magnetic field sensor <NUM> is connected to the control circuit <NUM> for evaluation. The detection device <NUM> can be inserted in the second housing <NUM> that may be similar to a housing of an auxiliary switch. The detection device <NUM> can be optionally retrofitted. The magnet <NUM> has to be retrofitted also or is fixed in the circuit breaker <NUM> regardless of whether a customer intends to add the detection device <NUM>. The detection device <NUM> may, for example, provide the overload status by the detection signal SD1 in form of a PWM signal at the first output terminal <NUM> that is a digital output. The detection signal SD1 can be evaluated by a higher-level control device <NUM>.

Alternatively, the detection device <NUM> comprises two output terminals which provide the detection signal SD1 and a further detection signal e.g. at <NUM>% and <NUM>% overload. The detection signal SD1 and the further detection signal may be static signals.

Alternatively, the circuit breaker <NUM> includes exactly one current path (as shown in <FIG>) or includes two or more than three current paths.

Claim 1:
Circuit breaker, comprising
- a first and a second breaker terminal (<NUM>, <NUM>),
- a bimetal stripe (<NUM>),
- a first conduction line (<NUM>),
- a switch (<NUM>) with a first and a second contact (<NUM>, <NUM>), wherein the first conduction line (<NUM>) is electrically coupled to the first breaker terminal (<NUM>) and to the first contact (<NUM>) of the switch (<NUM>),
- a triggering device (<NUM>) mechanically coupling the bimetal stripe (<NUM>) to the switch (<NUM>),
- a magnet (<NUM>) connected to at least one of the bimetal stripe (<NUM>), the triggering device (<NUM>) and the switch (<NUM>),
- a detection device (<NUM>) comprising a magnetic field sensor (<NUM>) configured to detect a magnetic field of the magnet (<NUM>) and a control circuit (<NUM>) connected to the magnetic field sensor (<NUM>), and
- a first housing (<NUM>) which at least encloses the bimetal stripe (<NUM>), the first conduction line (<NUM>), the switch (<NUM>), the triggering device (<NUM>) and the magnet (<NUM>),
characterized in that
the first conduction line (<NUM>) is wound around the bimetal stripe (<NUM>),
wherein the circuit breaker (<NUM>) comprises a second housing (<NUM>) which at least encloses the detection device (<NUM>), and wherein the magnetic field sensor (<NUM>) is outside of the first housing (<NUM>) and is configured to detect a movement of the magnet (<NUM>) inside the first housing (<NUM>).