Ultra-fast breaker

Abstract

The disclosure relates to a circuit breaker (100), comprising: a first axially movable electrical contact bar (106) configured to electrically connect stationary contacts (101, 108) in a closed position of the circuit breaker to enable a current flow (110) through the stationary contacts via the first axially movable electrical contact bar (106); an axially movable electrically insulating piston (105) attached to the first axially movable electrical contact bar; a second axially movable electrical contact bar (104) which is mechanically attached to the axially movable piston and electrically insulated from the first axially movable electrical contact bar; and electrically conductive axial rails (102, 107) being arranged to oppose each other. The second axially movable electrical contact bar is axially movable between the axial rails and electrically connects the electrically conductive axial rails. The electrically conductive axial rails are energizable by an activation current (121), thereby generating an electromagnetic field axially displacing the second axially movable electrical contact bar to displace the first axially movable electrical contact bar, whereby the stationary contacts are disconnected.

Description

[0001] ULTRA-FAST BREAKER

[0002] TECHNICAL FIELD

[0003] The disclosure relates to the field of ultra-fast interruption of fault currents in alternating current (AC) and direct current (DC) systems by using circuit breakers. The disclosure relates to a circuit breaker with electrically conductive axial rails which can be energized by an activation current for an ultra-fast interruption of fault currents.

[0004] BACKGROUND

[0005] Fast breakers are an emerging field. Normally such fast breakers are not needed since AC systems are dominant. However, due to the push of renewable energy technologies to reduce the emission of carbon dioxide gases, and increase efficiency, DC systems are becoming more and more important. Hence fast breakers are becoming very important. In many application scenarios, complete interruption speeds less than 1 ms are achieved by using solid-state breakers. However, solid-state breakers suffer from high conduction losses, they are expensive and less reliable and do not provide isolation. Since solid-state breakers are made of semiconductor materials, conductivity can be reduced resulting in high conduction losses. This often results in the need to use a cooling system such as water cooling which can be very expensive and less reliable. Lastly, semiconductors do not offer physical isolation and can have leakage currents limiting their use.

[0006] SUMMARY

[0007] This disclosure provides a solution for an ultra-fast circuit breaker for interrupting fault currents without suffering from the above-described problems. A reliable non-expensive circuit breaker is provided with an interruption speed less than 1 ms that does not suffer from conduction losses.

[0008] The disclosure presents an ultra-fast circuit breaker which is able to interrupt the circuit before any damage can happen to the circuit. In the event of a fault, the circuit breaker is able to open the electrical contacts very fast before the current has a chance to increase in magnitude and becomes harder to interrupt.

[0009] The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures. In this disclosure, the innovative use of an ultra-fast actuator is presented to drive the contacts of a circuit breaker really fast, in less than 500 us, or in less than 100 us.

[0010] Such ultra-fast actuator can be used to generate an impulsive force and interrupt a current in a system in the event of a fault. In embodiments, the contact system comprises two stationary contacts and a moving contact. The moving contact is attached to an armature, which can be made of aluminum, for example. The actuator consists of two stationary contacts that may be denoted as rails and a moving contact also called an armature. The rails can be made of copper, for example, and the armature can be made of any electrically conducting material, for example aluminum. Once the capacitor is discharged, a large current is produced that generates a force and drives the armature upwards. This armature is mechanically connected to the moving contact and hence causes the opening of the electrical circuit. Further details are described below with respect to Figure 1.

[0011] In order to describe the disclosure in detail, the following terms and notations will be used.

[0012] AC Alternating current

[0013] DC Direct current

[0014] PV Photovoltaic

[0015] LV Low voltage

[0016] According to a first aspect, the disclosure relates to a circuit breaker, comprising: a first axially movable electrical contact bar configured to electrically connect stationary contacts in a closed position of the circuit breaker to enable a current flow through the stationary contacts via the first axially movable electrical contact bar; an axially movable piston attached to the first axially movable electrical contact bar, wherein the axially movable piston is an electrical insulator; a second axially movable electrical contact bar which is mechanically attached to the axially movable piston and electrically insulated from the first axially movable electrical contact bar; and electrically conductive axial rails being arranged to oppose each other; wherein the second axially movable electrical contact bar is axially movable between the axial rails and electrically connects the electrically conductive axial rails; wherein the electrically conductive axial rails are energizable by an activation current, thereby generating an electromagnetic field axially displacing the second axially movable electrical contact bar to displace the first axially movable electrical contact bar, whereby the stationary contacts are disconnected.

[0017] Such a circuit breaker allows for an ultra-fast interruption of fault currents without suffering from the problems of solid-state circuit breakers as described above. The circuit breaker is a reliable non- expensive device with an interruption speed less than 1 ms that does not suffer from conduction losses. The circuit breaker is able to interrupt the circuit before any damage can happen to the circuit. In the event of a fault, the circuit breaker is able to open the electrical contacts very fast before the current has a chance to increase in magnitude and becomes harder to interrupt.

[0018] In an exemplary implementation of the circuit breaker, the electromagnetic field induces an impulsive force onto the second axially movable electrical contact bar to displace the first axially movable electrical contact bar. This impulsive force is generated very fast and urges the second axially movable electrical contact bar to displace the first axially movable electrical contact bar, resulting in fast actuation in the order of less than 1 us. Interruption speeds as fast as 100 us can be achieved.

[0019] In an exemplary implementation of the circuit breaker, the circuit breaker comprises: a capacitor electrically connected to the electrically conductive axial rails, wherein the capacitor is dischargeable over the electrically conductive axial rails to generate the activation current through the electrically conductive axial rails. Such capacitor, that can also be implemented as a capacitor bank, is able to provide the energy for energizing the electrically conductive axial rails when being charged.

[0020] In an exemplary implementation of the circuit breaker, the capacitor is discharged when the current flow through the stationary contacts reaches a fault current. This event can be precisely detected by a detection circuit, e.g., a semiconductor device, e.g., a FET.

[0021] In an exemplary implementation of the circuit breaker, the circuit breaker is configured to extinguish the fault current based on creation of at least one arc between the first axially movable electrical contact bar and the stationary contacts when the first axially movable electrical contact bar is displaced. By the arc, fast extinguishment of the fault current can be achieved in order to guarantee ultra-fast interruption of the current flowing through the stationary contacts.

[0022] In an exemplary implementation of the circuit breaker, splitter plates are electrically connected to the stationary contacts and configured to elongate a path of the at least one arc and to create further arcs between the first axially movable electrical contact bar and the stationary contacts. This results in larger arc voltages that eventually extinguish the arc and the fault current.

[0023] In an exemplary implementation of the circuit breaker, the circuit breaker is configured to drive the fault current down to zero based on the following relation: difaujt= - (Vsystem— Varc)dt where difau[tis the fault current derivative, Vsystemis a system voltage across the stationary contacts, Varcis an arc voltage between the first axially movable electrical contact bar and the stationary contacts and L is a system inductivity. This relation best describes the phenomenon of arc voltages. The higher the buildup of the arc voltage, the faster is the decay of the fault current.

[0024] In an exemplary implementation of the circuit breaker, the capacitor is electrically connected to the axial rails via a controllable semiconductor switch; wherein the capacitor is discharged by the controllable semiconductor switch. Such a controllable semiconductor switch provides an efficient mechanism for a controlled discharge of the capacitor upon detecting a fault current situation.

[0025] In an exemplary implementation of the circuit breaker, the circuit breaker comprises: a locking element configured to lock the axially movable piston after the disconnection of the stationary contacts in an open position of the circuit breaker to disable a current flow through the stationary contacts. Such a locking element provides a secure locking of the piston in a position in which the stationary contacts are in the open position.

[0026] In an exemplary implementation of the circuit breaker, the first axially movable electrical contact bar is moved back into the closed position of the circuit breaker to electrically connect the stationary contacts after the fault current has been extinguished. This allows for reusing the circuit breaker after the fault current has been extinguished.

[0027] In an exemplary implementation of the circuit breaker, the electrically conductive axial rails are energizable by a reverse activation current, thereby generating a reverse electromagnetic field axially moving the second axially movable electrical contact bar to electrically connect the first axially movable electrical contact bar with the stationary contacts. Such reverse activation current allows for a secure repositioning of the second axially movable electrical contact bar in its original position for reusing the circuit breaker.

[0028] In an exemplary implementation of the circuit breaker, the circuit breaker comprises: a second capacitor, electrically connected to the electrically conductive axial rails, wherein the second capacitor is dischargeable over the electrically conductive axial rails to generate the reverse activation current through the electrically conductive axial rails. Such second capacitor, that can also be implemented as a capacitor bank, is able to provide the energy for energizing the electrically conductive axial rails to move the second axially movable electrical contact bar in its original position for reusing the circuit breaker.

[0029] In an exemplary implementation of the circuit breaker, the activation current through the electrically conductive axial rails is in an order of kiloamperes or higher. Such high activation current allows an ultra-fast actuation to disconnect the stationary contacts very fast. For example, interruption speeds as fast as 100 us can be achieved.

[0030] In an exemplary implementation of the circuit breaker, the electrically conductive axial rails are made of Copper; and the second axially movable electrical contact bar is made of Aluminum or Copper. Copper has a high conductivity which results in excellent conductivity of the electrically conductive axial rails and thus fast reaction times. The second axially movable electrical contact bar is preferably made of Aluminum. However, Copper may also be used but is less favorable due to its higher mass.

[0031] In an exemplary implementation of the circuit breaker, the axially movable piston is made of glass fiber. Glass fiber is stable and elastic. Hence, displacement between the first axially movable electrical contact bar and the second axially movable electrical contact bar can be efficiently compensated.

[0032] In an exemplary implementation, the circuit breaker may be configured to drive the fault current down to zero in less than 100 microseconds. In other examples, more time may be required, e.g., 150, 200, 250, 300, 350, 400, 450, 500 or more microseconds.

[0033] According to a second aspect, the disclosure relates to a method for handling a circuit breaker according to the first aspect described above, the method comprising: detecting a fault current based on the current flow crossing a threshold; and generating the activation current upon detecting the fault current to disconnect the stationary contacts.

[0034] Such method allows an ultra-fast interruption of fault currents, thereby protecting the circuit from damage.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Further embodiments of the disclosure will be described with respect to the following figures, in which:

[0037] Figure 1 shows a schematic diagram illustrating a circuit breaker according to the disclosure; and

[0038] Figure 2 shows a schematic diagram illustrating a method for handling a circuit breaker according to the disclosure. DETAILED DESCRIPTION OF EMBODIMENTS

[0039] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the disclosure is defined by the appended claims.

[0040] It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

[0041] In the following, AC systems and DC systems as used in this disclosure are described.

[0042] Traditionally, AC systems dominated over DC systems mainly due to the reliance of transformers to deliver power over long distances. Transformers rely on AC and hence all electric utilities and most electric appliances relied on AC as an input. Phones or computers are such examples where they rely on an AC input that gets converted to DC to operate the PC. Datacenters are other such examples.

[0043] Another reason for the justification of AC systems is due to breakers. It is much easier to interrupt an AC system than a DC system. It is very difficult to interrupt a DC system due to the absence of a current zero crossing. In AC systems, the current crosses zero three times in one period. Hence, every 10 ms (for 50 Hz systems), the breaker has a chance to interrupt the current. However, in DC systems, since the current is constant, it poses a big challenge. The current has to be forced and taken down to zero artificially. Besides, in DC systems, the system inductance is much lower than comparable AC systems. Hence, fault currents can rise very rapidly leading to high current magnitudes and further away from a zero current crossing. This complicates the interruption process further and clearly shows the difficulty in interrupting a current that goes in the wrong direction.

[0044] In AC systems, the speed of the breaker is not so critical since the current will eventually go to zero regardless of the system and the breaker has a chance to interrupt fault currents every 10 ms. Consequently, AC breakers are not built for speed since it is expensive, complex, and unnecessary to do so. However, for DC systems, speed plays a major role. The faster the breaker, the faster it can react and limit fault currents. The smaller the short circuit current, the easier it is to interrupt, and the smaller is the energy that needs to be absorbed by the breaker. This results in a smaller footprint and leads to cost reduction in breaker design.

[0045] Another major advantage is maintenance and lifetime. The faster the mechanical breaker is at interrupting a fault current at low current magnitudes, the less are the contacts ablated. This results in a prolonged lifetime and much less maintenance increasing reliability.

[0046] The circuit breaker presented in this disclosure provides a solution to the above-described problems. It utilizes an ultra-fast actuator with high power density to accelerate the contacts of the breaker really fast. The breaker is so fast that even AC systems seem as a DC system to the breaker since it is able to completely interrupt fault currents within 100 us in a preferred embodiment. It does not wait for a current zero but creates its own by generating an arc voltage that is high enough to counteract the system voltage and drive the fault current down to zero. This principle can be used as a resettable fuse that is even faster and even more reliable.

[0047] The following figures illustrate the circuit breaker and a method for handling the circuit breaker in detail.

[0048] Figure 1 shows a schematic diagram illustrating a circuit breaker 100 according to the disclosure.

[0049] The circuit breaker 100 comprises: a first axially movable electrical contact bar 106 configured to electrically connect stationary contacts 101, 108 in a closed position of the circuit breaker 100 to enable a current flow 110 through the stationary contacts 101, 108 via the first axially movable electrical contact bar 106. The circuit breaker 100 comprises: an axially movable piston 105 attached to the first axially movable electrical contact bar 106. The axially movable piston 105 is an electrical insulator; a second axially movable electrical contact bar 104 which is mechanically attached to the axially movable piston 105 and electrically insulated from the first axially movable electrical contact bar 106; electrically conductive axial rails 102, 107 being arranged to oppose each other, as shown in Figure 1.

[0050] The second axially movable electrical contact bar 104 is axially movable between the axial rails 102, 107 and electrically connects the electrically conductive axial rails 102, 107. The electrically conductive axial rails 102, 107 are energizable by an activation current 121, thereby generating an electromagnetic field axially displacing the second axially movable electrical contact bar 104 to displace the first axially movable electrical contact bar 106, whereby the stationary contacts 101, 108 are disconnected. The electromagnetic field induces an impulsive force 120 onto the second axially movable electrical contact bar 104 to displace the first axially movable electrical contact bar 106.

[0051] The circuit breaker 100 may comprise a capacitor 103 electrically connected to the electrically conductive axial rails 102, 107 as shown in Figure 1. The capacitor 103 can be discharged over the electrically conductive axial rails 102, 107 to generate the activation current 121 through the electrically conductive axial rails 102, 107. The capacitor 103 can be discharged when the current flow 110 through the stationary contacts 101, 108 reaches a fault current, for example when the current flow 110 reaches a current threshold indicating a fault current.

[0052] The circuit breaker 100 may be configured to extinguish the fault current based on creation of at least one arc between the first axially movable electrical contact bar 106 and the stationary contacts 101, 108 when the first axially movable electrical contact bar 106 is displaced.

[0053] In one embodiment, splitter plates can be electrically connected to the stationary contacts 101, 108 and configured to elongate a path of the at least one arc and to create further arcs between the first axially movable electrical contact bar 106 and the stationary contacts 101, 108.

[0054] In an example, the circuit breaker 100 may be configured to drive the fault current down to zero based on the following relation: where difauitis the fault current derivative, Vsystemis a system voltage across the stationary contacts 101, 108 and Varcis an arc voltage between the first axially movable electrical contact bar 106 and the stationary contacts 101, 108.

[0055] The capacitor 103 may be electrically connected to the axial rails 102, 107 via a controllable semiconductor switch (not shown in Figure 1) which can be used to discharge the capacitor 103.

[0056] The circuit breaker 100 may comprise a locking element (not shown in Figure 1) that may be configured to lock the axially movable piston 105 after the disconnection of the stationary contacts 101, 108 in an open position of the circuit breaker 100 to disable a current flow 110 through the stationary contacts 101, 108. Such a locking element can be a spring, for example, or any other locking means. The first axially movable electrical contact bar 106 can be moved back into the closed position of the circuit breaker 100 to electrically connect the stationary contacts 101, 108 after the fault current has been extinguished.

[0057] The electrically conductive axial rails 102, 107 can be energized by a reverse activation current, for example, thereby generating a reverse electromagnetic field axially moving the second axially movable electrical contact bar 104 to electrically connect the first axially movable electrical contact bar 106 with the stationary contacts 101, 108.

[0058] In one example, the circuit breaker 100 may comprise a second capacitor (not shown in Figure 1), electrically connected to the electrically conductive axial rails 102, 107. The second capacitor can be discharged over the electrically conductive axial rails 102, 107, for example, to generate the reverse activation current through the electrically conductive axial rails 102, 107.

[0059] In some embodiments, the activation current 121 through the electrically conductive axial rails 102, 107 can be in an order of kiloamperes or higher, for example.

[0060] In some embodiments, the electrically conductive axial rails 102, 107 can be made of Copper, for example. In some embodiments, the second axially movable electrical contact bar 104 can be made of Aluminum or Copper, for example. The second axially movable electrical contact bar 104 is preferably made of Aluminum. However, Copper may also be used but is less favorable due to its higher mass.

[0061] In some embodiments, the axially movable piston 105 can be made of glass fiber, for example.

[0062] In an exemplary implementation, the circuit breaker 100 may be configured to drive the fault current down to zero in less than 100 microseconds. In other examples, more time may be required, e.g., 150, 200, 250, 300, 350, 400, 450, 500 or more microseconds.

[0063] Further embodiments of the circuit breaker 100 are described in the following.

[0064] The breaker (i.e. circuit breaker 100) consists of a pair of contacts. In the closed position, the contacts conduct the nominal current as shown in Figure 1 to the right. The nominal current path goes from current in (left side), then passes through the bridge, and goes out through the right copper terminal denoted by current out (right side). When a fault is detected, a trigger signal is sent to the breaker and the breaker opens the two contacts following a linear trajectory. Two arcs are created between the moving armature and the two stationary contacts. This arc is quickly elongated and ideally magnetically blown out towards magnetic splitter plates (not shown in Figure 1). The splitter plates elongate the path of the arc and create a magnitude of smaller arcs leading to higher voltages. As the moving contact moves further away, the arc gets elongated further and the number of smaller arcs increases further. This results in larger arc voltages that eventually extinguish the arc and the fault current. The equation that best describes this phenomenon is as follows:

[0065] The higher the build-up of the arc voltage, the faster is the decay of the fault current. Two contacts are used in this design to speed up the interruption process. Increasing the number of series connected contacts will increase the interruption speed further at the expense of adding resistance and more losses. This is a tradeoff.

[0066] To be able to open the contacts so rapidly, an ultra-fast actuator principle is used. In comparison to other actuators or motors, the disclosed ultra-fast actuator has a low inductance and relies on very high currents to generate large impulsive forces. Due to its low inductive nature, large current magnitudes can be generated that result in large magnetic fields. A magnetic field concentrates between the two stationary copper rails directed either inside or outside of the page depending on the current direction. The cross product of this magnetic field along with the radially directed current flow in the aluminum armature results in very large impulsive forces. A capacitor bank and a spark gap can be used to trigger the discharge of the capacitor bank to generate these currents. The spark gap can handle anywhere between 10 kA to 1 or 2 mega amperes, for example.

[0067] These impulsive forces repel the aluminum armature axially upwards. This aluminum armature is connected to the copper armature in the main current system via an insulating bar that is for example made of reinforced glass fiber. By utilizing such a breaker, interruption speeds as fast as 100 us, for example, can be achieved.

[0068] In the following, a further embodiment of the circuit breaker 100 is described that can be used as a preferred embodiment. Normally, during nominal operation when there is no fault, as shown in Figure 1, the current flows through “A” (101), then goes up to “F” (106) and goes back down to “H” (108) and leaves the breaker 100. “A” is the inlet copper busbar, “F” is the moving contact, and “H” is the outlet stationary contact.

[0069] A capacitor “C” (103) is used to store energy and sit idle waiting for fault. In the event of a fault, the capacitor can be triggered by a thyristor or any other semiconductor device to release its energy. A large impulsive current is formed in the order of kiloamperes, for example. The current flows through “B” (102) the left stationary rail that should be electrically conducting and may be made of copper ideally, and then passes through “D” (104) the armature and returns through “G” (107) the right stationary rail. “G” may also be ideally made of copper since it is highly conductive. “D” may be made of aluminum ideally since it is lighter than copper and is electrically conductive.

[0070] In the presence of high currents, in the order of hundreds of kiloamperes, for example, a large magnetic field is developed between the rails that will impact the armature. This will induce a large electromagnetic force that drives the armature forwards. Since the armature and the moving contact are coupled together by an insulating rod “E” (105), the moving contact also moves and interrupts the main current flow very rapidly. Thus “A” and “B” are now isolated and the main current path is interrupted.

[0071] As already described above, in AC systems, the current crosses zero every 10 ms. Every time it crosses zero, the circuit breaker has the potential to interrupt the fault current. Traditional AC breakers do not need to be fast. They just need to be reliable and robust. However new more efficient systems require DC and not AC. DC has numerous benefits and also low inductance and no current zero crossing. Due to the raw speed of the breaker described in this disclosure, it can interrupt both DC or AC currents extremely fast. Since it is so fast, it can act as a fault current limiter also protecting all equipment downstream. Moreover, since it is able to interrupt fault currents so fast, it does not have to be rated to absorb the full short circuit current and hence is able to interrupt the current while it is still small. This means the damage inflicted on the breaker is limited leading to more reliability and longer lifetimes without maintenance. This phenomenon can be compared to a snowball. It is much easier to stop a snowball at the top of the mountain before it starts to grow in size. On the other hand, stopping a snowball at the bottom of a mountain is very difficult since it will roll all the way increasing in both size and speed. Thus, the energy required to stop the snowball at the top of a mountain is much less than that at the bottom of a mountain.

[0072] The circuit breaker 100 presented in this disclosure has similar performance as a pure solid-state circuit breaker. However, it exhibits very low conduction losses and is able to conduct large currents. Furthermore, it has similar interruption speeds, is more reliable, and even provides galvanic separation. In principle, it can be made as fast as a semiconductor-based device while conducting large currents and not exhibiting any conduction losses. Moreover, this principle does not require a cooling system and costs a fraction of the cost of solid-state breakers.

[0073] Application scenarios of the circuit breaker 100 are datacenters, DC systems especially LVDC up to 1500 V, renewables such as PV, or electric vehicles and charging stations. The circuit breaker 100 is highly useful in DC systems or in any system where complete fault current interruption in less than 1 ms is mandatory.

[0074] The circuit breaker 100 presented in this disclosure thus provides a solution for a novel ultra-fast circuit breaker to interrupt fault currents in at least less than 1 ms. The circuit breaker 100 is a device for limiting and interrupting fault currents really fast with no (significant) conduction losses. The circuit breaker 100 can be deployed in datacenters, PV, battery systems, electric vehicles, or DC microgrids, for example.

[0075] Figure 2 shows a schematic diagram illustrating a method 200 for handling a circuit breaker according to the disclosure. The circuit breaker 100 may correspond to the circuit breaker 100 as described above with respect to Figure 1.

[0076] The method 200 comprises detecting 201 a fault current based on the current flow 110 through the stationary contacts 101, 108 (shown in Figure 1) crossing a threshold. The method 200 comprises generating 202 the activation current 121 for the electrically conductive axial rails 102, 107 (shown in Figure 1) upon detecting the fault current to disconnect the stationary contacts 101, 108 as shown in Figure 1. Such method allows an ultra-fast interruption of the fault current, thereby protecting the circuit from damage.

[0077] While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similarto the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms “coupled” and “connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other. Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

[0078] Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence.

[0079] Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the disclosure beyond those described herein. While the disclosure has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the disclosure. It is therefore to be understood that within the scope of the appended claims and their equivalents, the disclosure may be practiced otherwise than as specifically described herein.

Claims

CLAIMS:

1. A circuit breaker (100), comprising: a first axially movable electrical contact bar (106) configured to electrically connect stationary contacts (101, 108) in a closed position of the circuit breaker (100) to enable a current flow (110) through the stationary contacts (101, 108) via the first axially movable electrical contact bar (106); an axially movable piston (105) attached to the first axially movable electrical contact bar (106), wherein the axially movable piston (105) is an electrical insulator; a second axially movable electrical contact bar (104) which is mechanically attached to the axially movable piston (105) and electrically insulated from the first axially movable electrical contact bar (106); and electrically conductive axial rails (102, 107) being arranged to oppose each other; wherein the second axially movable electrical contact bar (104) is axially movable between the axial rails (102, 107) and electrically connects the electrically conductive axial rails (102, 107); wherein the electrically conductive axial rails (102, 107) are energizable by an activation current (121), thereby generating an electromagnetic field axially displacing the second axially movable electrical contact bar (104) to displace the first axially movable electrical contact bar (106), whereby the stationary contacts (101, 108) are disconnected.

2. The circuit breaker (100) of claim 1, wherein the electromagnetic field induces an impulsive force (120) onto the second axially movable electrical contact bar (104) to displace the first axially movable electrical contact bar (106).

3. The circuit breaker (100) of claim 1 or 2, comprising: a capacitor (103) electrically connected to the electrically conductive axial rails (102, 107), wherein the capacitor (103) is dischargeable over the electrically conductive axial rails (102, 107) to generate the activation current (121) through the electrically conductive axial rails (102, 107).

4. The circuit breaker (100) of claim 3, wherein the capacitor (103) is discharged when the current flow (110) through the stationary contacts (101, 108) reaches a fault current.

5. The circuit breaker (100) of claim 4,configured to extinguish the fault current based on creation of at least one arc between the first axially movable electrical contact bar (106) and the stationary contacts (101, 108) when the first axially movable electrical contact bar (106) is displaced.

6. The circuit breaker (100) of claim 5, wherein splitter plates are electrically connected to the stationary contacts (101, 108) and configured to elongate a path of the at least one arc and to create further arcs between the first axially movable electrical contact bar (106) and the stationary contacts (101, 108).

7. The circuit breaker (100) of any of claims 4 to 6, configured to drive the fault current down to zero based on the following relation:where difauitis the fault current derivative, Vsystemis a system voltage across the stationary contacts (101, 108) and Varcis an arc voltage between the first axially movable electrical contact bar (106) and the stationary contacts (101, 108).

8. The circuit breaker (100) of any of claims 4 to 7, wherein the capacitor (103) is electrically connected to the axial rails (102, 107) via a controllable semiconductor switch; wherein the capacitor (103) is discharged by the controllable semiconductor switch.

9. The circuit breaker (100) of any of claims 4 to 8, comprising: a locking element configured to lock the axially movable piston (105) after the disconnection of the stationary contacts (101, 108) in an open position of the circuit breaker (100) to disable a current flow (110) through the stationary contacts (101, 108).

10. The circuit breaker (100) of any of claims 4 to 9, wherein the first axially movable electrical contact bar (106) is moved back into the closed position of the circuit breaker ( 100) to electrically connect the stationary contacts (101, 108) after the fault current has been extinguished.

11. The circuit breaker ( 100) of any of the preceding claims, wherein the electrically conductive axial rails (102, 107) are energizable by a reverse activation current, thereby generating a reverse electromagnetic field axially moving the secondaxially movable electrical contact bar (104) to electrically connect the first axially movable electrical contact bar (106) with the stationary contacts (101, 108).

12. The circuit breaker (100) of claim 11, comprising: a second capacitor, electrically connected to the electrically conductive axial rails (102, 107), wherein the second capacitor is dischargeable over the electrically conductive axial rails (102, 107) to generate the reverse activation current through the electrically conductive axial rails (102, 107).

13. The circuit breaker ( 100) of any of the preceding claims, wherein the activation current (121) through the electrically conductive axial rails (102, 107) is in an order of kiloamperes or higher.

14. The circuit breaker (100) of any of the preceding claims, wherein the electrically conductive axial rails (102, 107) are made of Copper; and wherein the second axially movable electrical contact bar (104) is made of Aluminum orCopper.

15. The circuit breaker ( 100) of any of the preceding claims, wherein the axially movable piston (105) is made of glass fiber.

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