Circuit breaker

Abstract

A circuit breaker is specified herein, comprising: - an electrically controllable switch (2) for switching an electric current line between a first terminal (31) and a second terminal (32), wherein - the circuit breaker (1) is pluggable into a fuse holder (4).

Description

[0001] Description

[0002] Circuit breaker

[0003] A circuit breaker is speci fied herein .

[0004] Circuit breakers as well as fuses can be used for protecting electric circuits and / or devices from a short circuit or from an electric overload . In contrast to circuit breakers that comprise e . g . a controllable switch, a fuse is a single-use , sacri ficial electrical component comprising a metal wire or strip that melts in case of an electric overcurrent and needs to be physically replaced after it has operated . In particular, NH fuses are a class of standardi zed low voltage , high power fuses that have a speci fic form factor and are widely used in utility power applications , electrical substations , electrical distribution systems or house j unction boxes , for example .

[0005] In addition to revising over-aging equipment and replacing a vast base of single-use NH fuses , utilities face an increasing demand for monitoring and remote control of electrical substations . Moreover, utilities are confronted with continuously more challenging operating conditions for existing grid structures , e . g . due to reverse power flow from de-centrali zed renewable energy sources , or due to increased peak and / or permanent load due to demands from electric vehicles , for example . Accordingly, there might be a demand for a modern replacement of single-use fuses that can be readily installed in the existing electrical infrastructure and / or that can provide additional functionality compared to single-use fuses . At least one obj ect of certain embodiments is to provide a retrofittable circuit breaker . This obj ect is solved by the subj ect matter according to the independent claim . Further embodiments and further advantageous developments are speci fied in the dependent claims .

[0006] According to an aspect , the circuit breaker comprises an electrically controllable switch for switching an electric current line between a first terminal and a second terminal . In particular, an electric current can flow between the first terminal and the second terminal via the electric current line i f the electrically controllable switch is in a closed state , whereas no electric current can flow i f the electrically controllable switch is in an open state . For example , the electrically controllable switch can be switched by applying an electric voltage and / or an electric current to control terminals of the electrically controllable switch .

[0007] In particular, the circuit breaker is an alternating current (AC ) and / or a direct current ( DC ) circuit breaker that protects a load and / or an electric circuit from an electric overload or from a short circuit , for example . For example , the circuit breaker is rated for a maximum operating voltage of 1000 Volts AC, or 1500 Volts DC . For example , the circuit breaker is rated for a maximum operating current between 2 Ampere and 1250 Ampere .

[0008] According to a further aspect , the circuit breaker is pluggable into a fuse holder . In particular, the fuse holder is configured for mechanically fixing and electrically contacting a fuse . For example , the fuse holder comprises a clamping connector for mechanically fixing and electrically contacting a fuse . For example , the fuse holder is configured to hold a fuse with a standardi zed mounting type and / or with a standardi zed form factor . It is also possible that the fuse holder is configured to hold a fuse with a non-standardi zed mounting type and / or with a non-standardi zed form factor .

[0009] In particular, the circuit breaker is configured for easily replacing a fuse with a speci fic mounting type and / or form factor . For example , the first and second terminals of the circuit breaker have an identical geometric arrangement and / or an identical form factor than a corresponding fuse type . For example , the first terminal and the second terminal are configured for a clamping connection with the fuse holder . In particular, the first terminal and the second terminal are configured for a reversible clamping connection with the fuse holder .

[0010] According to an embodiment , the circuit breaker comprises :

[0011] - an electrically controllable switch for switching an electric current line between a first terminal and a second terminal , wherein

[0012] - the circuit breaker is pluggable into a fuse holder .

[0013] Among others , the circuit breaker described herein is based on the idea that a common fuse holder can be retrofitted with a modern circuit breaker, in particular with an electronic or digital circuit breaker . Advantageously, this allows to reuse the existing, well established electrical fuse holder infrastructure while adding functionality compared to standard single-use fuses . Accordingly, the circuit breaker disclosed herein advantageously saves installation costs and further is reusable . Furthermore , by using the circuit breaker described herein, a physical replacement of a fuse is no longer necessary after an electric overload or short- circuit event , for example , thereby reducing service costs .

[0014] Moreover, compared to a standard fuse , the circuit breaker described herein can add additional monitoring and / or remote controlling capabilities . Further, a safety of the load or electric circuit that is to be protected by the circuit breaker or fuse can be advantageously increased, as the circuit breaker can be triggered more precisely and / or under better defined circumstances compared to a single-use fuse , for example . Lastly, the circuit breaker can lead to a reduced power loss compared to a single-use fuse .

[0015] According to a further aspect , the circuit breaker further comprises a housing, and the first terminal and the second terminal are formed as metal blades that are arranged on opposite sides of the housing along a common axis . For example , the first terminal and / or the second terminal is formed as a kni fe blade or a tag . For example , the metal blades are configured for a clamping connection or a bolted tag fuse-link connection with the fuse holder or with a bus bar . For example , the metal blade of the first and / or second terminal comprises a through-hole or a cut-out for a screw or bolt connection of the circuit breaker with the fuse holder . It is also possible that the metal blades of the first terminal and the second terminal are of fset , e . g . in parallel , with respect to each other or with respect to the common axis .

[0016] According to a further aspect of the circuit breaker, the fuse holder is a NH fuse base or a NH fuse strip . In particular, the NH fuse base is configured to hold a standardi zed NH fuse . For example , the NH fuse base comprises fuse clamps for mechanically fixing and electrically contacting the metal blade of the first terminal and of the second terminal of the circuit breaker . For example , the circuit breaker comprises a housing with extraction lugs such that the circuit breaker can be installed into and / or removed from the fuse holder using a standardi zed NH fuse extraction handle .

[0017] According to a further aspect of the circuit breaker, the electrically controllable switch comprises a semiconductor switch and / or a mechanical switch . In particular, the semiconductor switch has no mechanically movable contacts for switching the electric current line between the first and second terminals . For example , the semiconductor switch is a unidirectional switch or a bidirectional switch . In contrast to the unidirectional switch, the bidirectional switch is configured for conducting an electric current in both directions and / or the bidirectional switch can sustain voltages of opposite polarities . For example , the semiconductor switch comprises or consists of one or more unipolar transistors , such as a field ef fect transistor, one or more bipolar transistors , in particular an insulated gate bipolar transistor ( IGBT ) , and / or one or more thyristors . Further, the semiconductor switch can comprise one or more diodes , for example . In particular, the semiconductor switch can be opened and / or closed by applying a gate voltage to the transistor and / or to the thyristor, for example .

[0018] In particular, the mechanical switch comprises at least one mechanically movable contact for opening and / or closing the electric current line between the first terminal and the second terminal . For example , the mechanical switch is an arcing switch without an arc quenching mechanism . Alternatively, the mechanical switch comprises an arc quenching mechanism for quenching an arc that can form between contacts of the switch upon opening and / or closing the switch under load . For example , the mechanical switch is electrically controlled via a magnetic actuator, such as a control coil , for opening and / or closing the mechanical switch .

[0019] According to a further aspect of the circuit breaker, the semiconductor switch and the mechanical switch are electrically connected in parallel . In particular, the circuit breaker comprises both, the mechanical switch and the semiconductor switch that are electrically connected in parallel between the first terminal and the second terminal . For example , the electrically controllable switch is a hybrid switch . In particular, an arc quenching mechanism may not be required i f the electrically controllable switch is a hybrid switch, wherein the electrically controlled switch is opened by first opening the mechanical switch while the semiconductor switch is closed and subsequently opening the semiconductor switch, for example . In particular, the mechanical switch can be configured as a bypass switch for bypassing the semiconductor switch during normal operation of the circuit breaker . Advantageously, by using a hybrid switch a switching time can be reduced and / or a li fetime of the electrically controllable switch can be increased compared to a circuit breaker that only consists of a mechanical switch, for example .

[0020] According to a further aspect , the circuit breaker further comprises a voltage clamping system electrically connected in parallel to the semiconductor switch . The voltage clamping system can be configured to limit a voltage increase due to an energy stored in the electric conduction line and / or in stray inductances when the semiconductor switch turns of f . For example , the voltage clamping system allows a voltage increase up to an allowed magnitude which is suf ficiently larger than a source voltage and less than a breakdown voltage of the semiconductor switch . For example , the voltage clamping system comprises or consists of a varistor, a transient voltage suppressor and / or a snubber .

[0021] According to a further aspect , the circuit breaker further comprises a control unit for controlling the electrically controllable switch . For example , the control unit comprises or consists of an integrated circuit , such as an application speci fic integrated circuit (AS IC ) . For example , the control unit comprises one or more input terminals for acquiring sensor or monitoring signals from one or more sensors , such as a current sensor, a voltage sensor, and / or a temperature sensor . For example , the control unit comprises one or more output terminals for sending control signals to the mechanical switch and / or the semiconductor switch .

[0022] According to a further aspect of the circuit breaker, the control unit is further configured for measuring an electric current flowing between the first terminal and the second terminal during operation . In particular, the circuit breaker comprises a current sensor that is electrically connected to an input of the control unit . For example , the current sensor comprises a Hall sensor and / or a coil for measuring the electric current flowing through the electric current line during operation of the circuit breaker .

[0023] For example , the circuit breaker can have an additional functionality as an on-board current meter or power meter for monitoring the electric current and / or the electric power used by a load that is connected to the circuit breaker during operation . Further, the circuit breaker can have an additional functionality for load switching or load shedding of low-voltage substations , for example . In particular, the circuit breaker or a plurality of the circuit breakers can be controlled to distribute loads among or between di f ferent utility substations , for example .

[0024] According to a further aspect of the circuit breaker, a timecurrent characteristic curve is stored in a memory of the control unit . In particular, the time-current characteristic curve speci fies a relation between the magnitude of the electric load current flowing along the electric current line and a melting time of a fuse , or analogously of an operating time or time-to-open of the circuit breaker . For example , the control unit stores one or more time-current characteristic curves of speci fic fuse types that the circuit breaker is supposed to replace . Accordingly, the circuit breaker can mimic the triggering behavior of an ordinary single-use fuse , for example .

[0025] Alternatively or in addition, the control unit can store one or more optimi zed time-current characteristic curves that are tailored for protecting a speci fic load and / or an electric circuit connected to the circuit breaker, for example . In particular, the optimi zed time-current characteristic curves can be designed for an increased safety of the load and / or of the electric circuit . For example , the optimi zed time-current characteristic curve can speci fy precise triggering times for given load currents that would not be achievable with standard single-use fuses . Advantageously, due to the electronic switching of the electric current line , the circuit breaker disclosed herein allows for an advanced selectivity with various current limiting options or settings compared to a standard single-use fuse . Further, by use of the circuit breaker described herein the protection of the load can be better compared to a melting fuse due to a reduced I2t energy of the circuit breaker, for example .

[0026] According to a further aspect of the circuit breaker, the control unit controls the electrically controllable switch according to the stored time-current characteristic curve . For example , the control unit measures the electric current flowing between the first and second terminals during operation and electrically disconnects the first and second terminals by opening the electrically controllable switch after a time corresponding to the measured electric current according to the stored time-current characteristic curve . According to a further aspect of the circuit breaker, the control unit is further configured for a bidirectional data trans fer with an external monitoring unit via a wired or wireless communication link . For example , the control unit is configured for a wireless data connection with a WiFi or Zigbee network . Alternatively or in addition, the control unit can comprise a serial bus plug, such as a RJ45 connector, for a wired connection to the external monitoring unit . In particular, for utilities applications a wired connection can be advantageous due to its increased data security compared to a wireless connection, while a wireless connection advantageously does not require an additional wiring infrastructure .

[0027] For example , the monitoring unit receives data from one or more sensors of the circuit breaker, such as a current sensor, a voltage sensor, and / or a temperature sensor . Further, the monitoring unit can receive data about the state of the electrically controllable switch, such as i f and / or when the circuit breaker has triggered, for example .

[0028] According to a further aspect of the circuit breaker, the control unit is further configured for a remote switching of the electrically controllable switch . For example , the monitoring unit can control the circuit breaker by sending signals to the control unit for remote switching of the electrically controllable switch . Advantageously, the circuit breaker can thus be remotely switched for load shedding and / or load switching applications , for example . Accordingly, the circuit breaker has an increased functionality compared to a single-use fuse . For example , the control unit utili zes a standard gateway, such as a substation automation gateway ( short : SMP gateway) , for remote operation and / or monitoring of the circuit breaker .

[0029] According to a further aspect of the circuit breaker, electric power for operating the control unit is supplied via the first and second terminals . For example , the circuit breaker comprises a voltage trans former, such as a coil wound around the electric current line that connects the first and second terminals via the electrically controllable switch, for supplying electric power to the control unit and the sensors , for example . Alternatively or in addition, the circuit breaker can comprise a battery, preferably a rechargeable battery, for at least a temporary electrical power supply of the control unit .

[0030] According to a further aspect , the circuit breaker is hot pluggable . In particular, the circuit breaker can be installed under load and / or while an electric voltage is applied to the fuse holder . For example , the electrically controllable switch is in the open state per default , e . g . before the circuit breaker is plugged into the fuse holder . Accordingly, the formation of an arc can be avoided when the circuit breaker is plugged into the fuse holder, thereby increasing an installation safety . For example , the control unit comprises a timer or time delay that closes the electrically controllable switch after a given time interval following the installation of the circuit breaker .

[0031] Further advantageous embodiments and further embodiments of the circuit breaker become apparent from the following exemplary embodiments described in connection with the figures .

[0032] Figure 1 shows a schematic perspective view of a circuit breaker 1 according to an exemplary embodiment .

[0033] Figure 2 shows a schematic circuit diagram of a circuit breaker according to an exemplary embodiment .

[0034] Elements that are identical , similar, or have the same ef fect , are denoted by the same reference signs in the figures . The figures and the proportions of the elements shown in the figures are not to be regarded as true to scale . Rather, individual elements may be shown exaggeratedly large for better representability and / or better understanding .

[0035] The circuit breaker 1 according to the exemplary embodiment in Figure 1 is an electronic or digital circuit breaker 1 comprising an electrically controllable switch 2 ( c . f . Fig . 2 ) for switching an electric current line connecting a first terminal 31 and a second terminal 32 of the circuit breaker 1 . For example , the electrically controllable switch 2 is a semiconductor switch 21 , a mechanical switch 22 or a hybrid switch that combines a semiconductor switch 21 with a mechanical switch 22 that are electrically connected in parallel ( c . f . Fig . 2 ) . The circuit breaker 1 further comprises a control unit 6 ( c . f . Fig . 2 ) for controlling the electrically controllable switch 2 . For example , during operation the control unit 6 measures the electric current flowing between the first and second terminals 31 , 32 and electrically disconnects the first terminal 31 from the second terminal 32 by opening the electrically controllable switch 2 i f a magnitude of the electric current exceeds a maximum allowed value .

[0036] The circuit breaker 1 has a form factor of a standardi zed NH fuse and is configured for easily replacing a standardi zed NH fuse by simply plugging the circuit breaker 1 into an existing NH fuse holder 4 . Speci fically, the circuit breaker 1 comprises a housing 5 wherein the first terminal 31 and the second terminal 32 are arranged on opposite sides of the housing 5 . The first terminal 31 and the second terminal 32 are formed as metal blades that are arranged parallel to each other along a common axis A. For example , the metal blades are bus bars configured for carrying large electrical currents up to e . g . 10 Ampere , 100 Ampere , or 1250 Ampere . The metal blades of the first terminal 31 and the second terminal 32 are configured for a clamping connection with an NH fuse holder 4 , a NH fuse base or a NH fuse strip . In particular, the NH fuse holder 4 comprises two clamps that mechanically hold an NH fuse or the circuit breaker 1 by clamping the metal blades of the first terminal 31 and the second terminal 32 . Further, the clamps of the NH fuse holder 4 establish an electric contact with the first and second terminals 31 , 32 , respectively . In particular, existing NH fuse bases 4 can be easily retrofitted with the circuit breaker 1 without requiring any installation of speci fic connectors or further components .

[0037] The circuit breaker 1 further comprises a network port 9 , such as a serial port , for connecting the control unit 6 to an external monitoring unit 7 ( c . f . Fig . 2 ) . Alternatively or in addition, the control unit 6 can be configured for connecting to the monitoring unit 7 via a wireless network . For example , the monitoring unit 7 can receive sensor data from the circuit breaker 1 , such as a current data, voltage data and / or temperature data . In particular, the circuit breaker 1 can be configured as a current meter that monitors the electrical current flowing between the two terminals during operation and can send respective data to the monitoring unit 7 , for example . Further, the monitoring unit 7 can remotely control and / or switch the electrically controllable switch 2 of the circuit breaker 1 for load switching or load shedding applications , for example .

[0038] The circuit breaker 1 also comprises status indicators 10 , such as light-emitting diodes , that indicate i f the circuit breaker is ready, operational , has tripped, and / or indicates a trip reason, for example . Further one of the status indicators 10 can indicate i f the circuit breaker is remote controlled or in an automatic mode , for example . It is to be noted that the present disclosure is not limited to the example of a circuit breaker 1 with the form factor of an NH fuse as shown in Figure 1 . Rather, the circuit breaker 1 can have the form factor of any standardi zed or non-standardi zed fuse , such as a bolted tag fuse-link, for example . Figure 2 shows a schematic circuit diagram of the circuit breaker 1 according to the exemplary embodiment described in connection with Figure 1 . The electrically controllable switch 2 is a hybrid switch comprising a semiconductor switch

[0039] 21 electrically connected in parallel to a mechanical switch

[0040] 22 and to a voltage clamping system 8 in the form of a varistor .

[0041] The semiconductor switch 21 comprises two IGBTs that are electrically connected in series such that their respective emitters are directly connected to one another . Further, each IGBT has a freewheeling diode electrically connected antiparallel to its controlled section . The gates of the two IGBTs are separately connected to the control unit 6 for electrically switching the respective IGBT . It is to be noted that the present disclosure is not limited to the example of the semiconductor switch 21 shown in Figure 2 . Rather, any suitable semiconductor switch 21 comprising or consisting of bipolar transistors , unipolar transistors , thyristors and / or diodes , for example , can be alternatively used .

[0042] A current sensor 11 is connected to the control unit 6 for measuring the current flowing between the first and second terminals 31 , 32 during operation . The control unit 6 transmits sensor data and / or status data, such as the value of the electric current measured by the current sensor 11 and / or a state of the electrically controllable switch 2 , to the external monitoring unit 7 via a wired or wireless network connection . Further, the monitoring unit 7 can remotely control the electrically controllable switch 2 by sending respective signals to the control unit 6 . This patent application claims the priority of German patent application DE 102024120832 . 5 , the disclosure content of which is hereby incorporated by reference . The invention is not restricted to the exemplary embodiments by the description on the basis of said exemplary embodiments . Rather, the invention encompasses any new feature and also any combination of features , which in particular comprises any combination of features in the patent claims and any combination of features in the exemplary embodiments , even i f this feature or this combination itsel f is not explicitly speci fied in the patent claims or exemplary embodiments .

[0043] References

[0044] 1 circuit breaker

[0045] 2 electrically controllable switch 21 semiconductor switch

[0046] 22 mechanical switch

[0047] 31 first terminal

[0048] 32 second terminal

[0049] 4 fuse holder 5 housing

[0050] 6 control unit

[0051] 7 monitoring unit

[0052] 8 voltage clamping system

[0053] 9 network port 10 status indicator

[0054] 11 current sensor

[0055] A common axis

Claims

Claims1. A circuit breaker (1) , comprising:- an electrically controllable switch (2) for switching an electric current line between a first terminal (31) and a second terminal (32) , wherein- the circuit breaker (1) is pluggable into a fuse holder (4) .

2. The circuit breaker (1) according to claim 1, wherein- the circuit breaker (1) further comprises a housing (5) , and- the first terminal (31) and the second terminal (32) are formed as metal blades that are arranged on opposite sides of the housing (5) along a common axis (A) .

3. The circuit breaker (1) according to any of claims 1 or 2, wherein the fuse holder (4) is a NH fuse base.

4. The circuit breaker (1) according to any of claims 1 to 3, wherein the electrically controllable switch (1) comprises a semiconductor switch (21) and / or a mechanical switch (22) .

5. The circuit breaker (1) according to claim 4, wherein the semiconductor switch (21) and the mechanical switch (22) are electrically connected in parallel.

6. The circuit breaker (1) according to any of claims 1 to 5, further comprising a control unit (6) for controlling the electrically controllable switch (2) .

7. The circuit breaker (1) according to claim 6, wherein the control unit (6) is further configured for measuring anelectric current flowing between the first terminal (31) and the second terminal (32) during operation.

8. The circuit breaker (1) according to claim 7, wherein- a time-current characteristic curve is stored in a memory of the control unit (6) , and- the control unit (6) controls the electrically controllable switch according to the stored time-current characteristic curve .

9. The circuit breaker (1) according to any of claims 6 to 8, wherein the control unit (6) is further configured for a bidirectional data transfer with an external monitoring unit (7) via a wired or wireless communication link.

10. The circuit breaker (1) according to any of claims 6 to9, wherein the control unit (6) is further configured for a remote switching of the electrically controllable switch (2) .

11. The circuit breaker (1) according to any of claims 6 to10, wherein electric power for operating the control unit (6) is supplied via the first and second terminals (31, 32) .

12. The circuit breaker (1) according to any of claims 1 to11, wherein the circuit breaker (1) is hot pluggable.

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