EP3987558B1

EP3987558B1 - Switch-disconnector with current detection

Info

Publication number: EP3987558B1
Application number: EP20732580.4A
Authority: EP
Inventors: Kris BEDNARSKI; Asad Mujawar; Varsha SABALE
Original assignee: Eaton Intelligent Power Ltd
Current assignee: Eaton Intelligent Power Ltd
Priority date: 2019-06-18
Filing date: 2020-06-12
Publication date: 2023-10-18
Anticipated expiration: 2040-06-12
Also published as: EP3987558A1; GB201911075D0; GB2585098A; WO2020254198A1

Description

Field

This relates to a switch-disconnector for opening, or interrupting, a current conduction path. In particular, this relates to a switch-disconnector with current detection for interrupting a current conduction path, optionally for interrupting a current conduction path in dependence on a detected current.

Background

A switch-disconnector, disconnect switch or isolator switch is used to break a current conduction path to ensure that an electrical circuit is de-energized and safe for service or maintenance. Such switch-disconnectors or switches are often found in electrical distribution and industrial applications. Switch-disconnectors can be operated either manually or automatically.
One approach to determining an overcurrent condition is to use an additional measurement module, external to the switch-disconnector but electrically connected to contact terminals of the switch-disconnector, to measure a current through the contact terminals. However, the use of an additional measurement module can increase overall dimensions and device complexity. It is desirable to provide an improved switch-disconnector for applications which require the rapid and reliable detection of an overcurrent condition, or for applications where switch-disconnector size or weight is a limiting factor.
GB 2 275 541 A discloses an electrical contactor 20 which has first 25 and second contacts movably mounted to engage for achieving continuity in an electrical circuit, via an electromagnet 22 and armature 24 defining a magnetic circuit with an air gap that closes in a first position of the contactor and opens in a second position of the contactor. A controller 30 switches an alternating current voltage to the coil 23 of the electromagnet during a timed portion of each AC half cycle, and senses 68 the current level in the coil in a feedback loop. The controller adjusts the voltage-on time to achieve a predetermined average current as needed for accelerating the armature or coasting during a closing operation, for holding the armature in place when closed, etc. In order to sense whether the contractor is presently open or closed, the controller monitors and stores the phase angle between the previous voltage zero crossing and the time of voltage turn-on. When the inductance of the magnetic circuit changes rapidly due to opening or closing of the air gap the controller detects a corresponding variation in the phase angle.

Summary

The matter for protection is set out in the enclosed claims.
The term "switch-disconnector" is used herein, but it will be understood that the principles described herein can apply equally to other disconnectors or disconnector devices such as circuit breakers, load disconnectors or any other form of electrical disconnection device.
Disclosed herein is a disconnector device of the first aspect, according to the invention, having a switch, the switch comprising: a first, fixed, contact terminal of a first conductor, a second, fixed, contact terminal of a second conductor, and a moveable bridge contact. The disconnector further comprises an actuating mechanism configured to open and close the switch by actuation of the moveable bridge contact, wherein the actuating mechanism is configured to move the bridge contact in a direction from a first position to a second position, wherein in the first position the switch is closed and the bridge contact is in electrical contact with the first and second contact terminals to define a current conduction path, and wherein in the second position the switch is open and the bridge contact is electrically separate from the first and second contact terminals. The disconnector further comprises: a detection coil disposed around the first contact terminal or the second contact terminal of the switch, the detection coil configured to output a signal indicative of a current through the respective contact terminal; and a communication module communicatively coupled to the detection coil and configured to receive the signal indicative of a current through the respective contact terminal and provide an output signal in dependence on the received signal. By placing the detection coil around the contact terminal, and so within the disconnector itself, a smaller and more robust disconnector may be provided, since auxiliary measurement units are not required.
The disconnector further comprises a housing, where the switch is disposed within the housing. In this way, the coil is integral to the disconnector, rather than included in an auxiliary module. The housing comprises a front portion which is accessible to a user in normal use. The communication module is external to the housing, optionally coupled to the front portion of the housing. The detection coil can be accessible (for example to a user) through the front of the housing.
The respective first or second contact terminal around which the detection coil is disposed can be non-linear, i.e. can comprise one or more angled portions. In some examples, the respective contact terminal comprises a "U" shaped portion having a first bend and a second bend, and wherein the detection coil is disposed on the respective contact terminal between the first and second bends. This arrangement can facilitate placement of the detection coil within the disconnector, since the geometry of the contact can accommodate the coil, without requiring a larger disconnector to be provided.
In some examples, an end of the first contact terminal extends parallel to one end of the bridge contact and an end of the second contact terminal extends parallel to the other end of the bridge contact, and wherein the ends of the bridge contact and the ends of the first and second contact terminals are inclined away from the direction of movement of the bridge contact. Optionally, the ends of the bridge contact are inclined away from the direction of movement of the bridge contact by an angle, a. Optionally, the angle, α, is between 15 degrees and 75 degrees, optionally the angle is between 30 degrees and 60 degrees, optionally the angle is 45 degrees. In some examples, the housing comprises ventilation openings substantially aligned with the ends of the bridge contact, or aligned along a direction which extends away from the ends of the bridge contact, optionally aligned along a direction perpendicular to the direction of movement of the bridge. This arrangement can facilitate improved arc suppression. In some examples, vents and improved efficacy of venting of the hot gases from the disconnector.
In some examples, the signal indicative of a current comprises a voltage value indicative of a current through the respective contact terminal. Optionally, the detection coil comprises a Rogowski coil and the voltage value is proportional to a rate of change of current through the respective contact terminal.
The detection coil is electrically connected to the communication module. Optionally, the communication module is a wireless communication module configured to wirelessly provide the output signal to one or more external devices, and the detection coil is electrically connected to a transmitter of the communication module. The transmitter can be configured to wirelessly transmit the output signal from the communication module to the external device(s). This arrangement may allow for easier retro-fitting of the communication module. Moreover, some processing tasks can be delegated to a central processing device which services multiple disconnectors; material and manufacturing costs may be reduced by having fewer processing electronics at the disconnector.
The communication module can be configured to determine a current through the respective contact terminal based on the voltage value, and to output an (output) signal in dependence on the determined current. The output signal can be indicative of a current through the respective contact terminal, optionally, the output signal can be a warning signal indicating a current through the respective contact terminal satisfies a predetermined threshold. By providing pre-emptive warnings, for example when a current exceeds a pre-determined threshold, safety may be improved.
In some examples the actuating mechanism is automatically controlled, in dependence on the output signal, to actuate the bridge contact. Alternatively, the disconnector can be manually actuated.
In some examples, a second detection coil is disposed around the other of the first contact terminal or the second contact terminal, the second detection coil configured to output a second signal indicative of a current through the respective contact terminal. The communication module is communicatively coupled to the second detection coil (for example, connected via an electrical or galvanised connection) and is configured to receive the second signal and output a signal in dependence on the received signal and/or the received second signal.
Disclosed herein is a disconnector of the second aspect, not according to the invention, the disconnector comprising: a first, fixed, contact terminal; a second, fixed, contact terminal; and a bridge contact moveable in a direction between a first position and a second position upon actuation. The first, second and bridge contacts define a switch of the disconnector. In the first position the bridge contact is in electrical contact with the first and second contact terminals to define a current conduction path, and in the second position the bridge contact is electrically separate from the first and second contact terminals (the switch can be open/closed or closed/open, as appropriate). An end of the first contact terminal extends parallel to one end of the bridge contact, and an end of the second contact terminal extends parallel to the other end of the bridge contact, wherein the ends of the bridge contact and the ends of the first and second contact terminals are inclined away from the direction of movement of the bridge contact.
The ends of the bridge contact and the ends of the first and second contact terminals can be inclined away from the direction of movement of the bridge contact by an angle, a. Optionally, the angle, α, is between 15 degrees and 75 degrees, optionally the angle is between 30 degrees and 60 degrees, optionally the angle is 45 degrees.
The disconnector can comprises a housing, the switch disposed within the housing (i.e. the first and second contact terminals disposed within the housing). The housing can comprise ventilation openings or vents, which may optionally be substantially aligned with the ends of the bridge contact or in a direction perpendicular to the direction of movement of the bridge contact. These vents draw away the gases created during the arc formation, providing a safer and more robust disconnector.
The housing can comprise a front portion which is accessible (for example to a user) in normal use. The ends of the bridge contact and the ends of the first and second contact terminals can extend in a direction away from the front portion of the housing, such that venting of the gases generated during arc formation occurs at the back of the device. This can improve safety.
Disclosed is an electrical apparatus comprising any embodiment of the disconnector.

Brief Description of the Drawings

The following description is with reference to the following Figures:

Figure 1 illustrates a perspective view of an exterior of a switch-disconnector;
Figure 2: Figure 2A illustrates a side view of an interior of a switch-disconnector, and Figure 2B shows a side view of a portion of Figure 2A (portion A, bounded by the dashed box);
Figure 3 illustrates a side-on perspective view of an interior section of a switch-disconnector;
Figure 4 illustrates a side-on plan view of a contact terminal comprising a detection coil;
Figure 5 shows a schematic illustration of a switch-disconnector;
Figure 6A illustrates a side-on plan view of an interior of switch-disconnector; and
Figure 6B shows a detail view of the switch within the switch-disconnector of Figure 6A.

Detailed Description

With reference to Figure 1 and Figure 2 (Figures 2A and 2B), a switch-disconnector 100 for opening a current conduction path is described. Switch-disconnector 100 is described herein as a switch-disconnector to isolate an electrical component (typically after a current has been interrupted by another control device due to the low load capability of the switch-disconnector), although it will be understood that the principles described herein could be applied to a load or switch switch-disconnector or circuit breaker or any other form of electrical disconnection device. Due to the low load capability of switch-disconnectors, the size and dimensions of such devices are typically reduced as compared to high load devices like circuit breakers; it can therefore be particularly desirable to provide an improved switch-disconnector for applications where switch-disconnector size or weight is a limiting factor.
Switch-disconnector 100 comprises a switch 142, the switch comprising a first contact terminal 104 of a first conductor, a second contact terminal 106 of a second conductor, and bridge contact 108. These components are separate, conducting, components of the switch, arranged to define a current conduction path (when the contact terminals 104, 106 are electrically connected to an external circuit upon installation of the switch-disconnector 100) by way of electrical contact between the first and second contact terminals 104, 106 and the bridge contact 108.
The first and second contact terminals 104, 106 are fixed, rigid, components of the switch 142, and the bridge contact 108 is a moveable switching component. For example, in a first position of the bridge contact 108, the bridge contact and first and second contact terminals 104, 106 are in electrical contact and define the current conduction path. In this position, the switch is closed and current can flow through the switch 142. In this example, movement of the bridge contact 108 in a direction 116 towards a second position, in which the bridge contact and first and second contact terminals 104, 106 are electrically separate, opens the switch 142. Opening the switch 142 breaks the current conduction path and isolates from its power source any apparatus which is connected to the electrical circuit on which the switch-disconnector is arranged. In particular, actuation of the bridge contact 108 in the direction 116 causes this electrical separation to occur by way of the physical separation of the bridge contact 108 from the first and second contact terminals. This actuation is reversible, in that the bridge contact can move between the first and second directions in response to appropriate actuation; an apparatus may thus be disconnected or connected to a power source, as appropriate.
Switch-disconnector 100 further comprises a housing 112, enclosing the components of switch 142. In particular, the first and second contact terminals 104, 106 of conductors and the bridge contact 108 are disposed within the housing 112 of the switch-disconnector 112. In other words, the first and second contact terminals 104, 106 are the end portions of conductors via which the device is connected to an external circuit and are the portions which are used within the switching mechanism of a switch-disconnector, i.e. the portions which make or break the circuit. Connection of the conductors associated with the first and second contact terminals to an external circuit outside of the housing 112 of the switch-disconnector can be by way of any suitable electrical connection, and suitable openings in the housing 112 can allow for such connection.
With further reference to Figure 3, actuation of the bridge contact is controlled by an actuating mechanism 114 of the switch-disconnector 100. In one example, a rotational movement of rotary component 114a (here shown as a manually operated knob, but any other suitable component may be used) of the actuating mechanism 114 causes actuation of the bridge contact 108 in direction 116 (i.e. from the first position to the second position), and vice versa. This linear actuation can be by way of a linear component 114b of the actuating mechanism 114, shown here as comprising a resilient member 114b in the form of a spring, or coil. However, it will be understood that any suitable actuating mechanism 114 can be used for moving the bridge contact 108 away from the first and second contact terminals 104, 106 in order to electrically separate the components.
With further reference to Figures 3 and 4, one or more detection coils 110 are disposed around the first contact terminal 104 and/or the second contact terminal 106 to measure the current through the contact terminal. In this way, the detection coil 100 is disposed directly onto the contact terminals of the switch 142, rather than in a separate module. By placing the detection coil directly on the switch, rather than in a separate module, a smaller device may be provided and the device may therefore be more easily deployed in space limited environments. In the example described herein, one detection coil 110 is disposed around the first contact terminal 104, but there may be one detection coil 110 disposed around either of the first or second contact terminals, or two detection coils 110, one disposed around each of the first and second contact terminals. The operation of the detection coil will be described in more detail below, with reference to Figure 5.
By placing the detection coil 110 directly onto the contact terminals of the switch 142, rather than on a portion of the conductor associated with the contact terminals or on an auxiliary conductor electrically connected to the switch-disconnector, a more compact switch-disconnector may be provided, which can be advantageous in applications where weight and/or size is limited.
The contact terminal (terminal 104 and/or 106) around which the detection coil 110 is disposed can be shaped so as to accommodate inclusion of the coil not only within the housing 112 of the detector, but directly onto the contact terminal. This arrangement facilitates a more compact switch-disconnector, which is cost effective in terms of manufacturing and allows for direct measurement of the current through the contact terminal, without the need for intermediary conductors; more reliable results may therefore be provided. In one example, the contact terminal (104 and/or 106) is non-linear, and for example, comprises one or more angled portions along the length of the terminal. The angled portions can be arranged to accommodate the coil 100 around the contact terminal itself.
In a particular implementation of this example, the first and/or second contact terminal (s) may be provided in a "U" shaped arrangement, or comprising a "U" shaped portion. This "U" shaped portion comprises first 138 and second 140 bends and the detection coil 110 can be clipped onto or otherwise disposed around the portion of the contact terminals between the two bends 138, 140 (as illustrated in Figure 4). In this arrangement the first and second bends are substantially 90 degree bends, but it will be understood that the bends may be arranged at any suitable angle. In some examples, the first and/or second bend may be between 45 degrees and 90 degrees, optionally between 60 degrees and 90 degrees. The particular angle of the first and second bends will be dependent on the size and geometry of the switch-disconnector 100.
The housing 112 comprises a front portion 112a (see e.g. Figure 1) which, in normal use of the switch-disconnector, for example when the switch-disconnector 100 is installed on a device or within a cabinet, is accessible to a user. For example, the front portion 112a can be accessible for a user to actuator rotary component 114a. The interior of the housing 112 can be moulded to support the bent or shaped contact terminals of switch 142 and to provide access to the detection coil 110 via the front portion 112a of the housing. For example, when the contact terminal(s) comprise a "U" shaped portion, the portion between the first and second bends may be orientated towards the front portion of the housing, and the open portion may be orientated away from the front of the housing. This arrangement can facilitate improved retro-fitting of a detection coil 110 in suitable devices, whilst also enabling a compact switch-disconnector to be provided. Alternatively, any other suitable contact terminal geometry may be used to facilitate provision of one or more detection coils 110 directly around the contact terminal(s) and within the housing 112.
With further reference to Figure 5, detection coil 110 is communicatively connected to a communication module 102 associated with the switch-disconnector 100 (here through an electrical/galvanised connection). The detection coil no is configured to output a signal 124 indicative of a current through the respective contact terminal; the communication module 102 is configured to receive the signal indicative of a current through the respective contact terminal and provide an output signal 126 in dependence on the received signal. In one example, the detection coil 110 is arranged such that the signal 124 it outputs is a voltage, or voltage value, which is indicative of a current through the first contact terminal 104 (i.e. the current through the contact terminal induces a voltage in the detection coil 110).
In some examples, the detection coil 110 has a direct electrical connection, i.e. via a wire or other conductor, to the communication module 102 for passing of signal 124 from the coil 110 to the communication module 102. This direct electrical connection may be made by way of openings 128 in a moulding of the housing 112 (see Figure 3) using e.g. an electrical or galvanised connection. In other examples, the detection coil 110 may be electrically connected (again, via openings 128) to the communication module by any other suitable connection. The communication module 102 is configured to process the signal 124 and produce the output signal 126 in dependence on the received signal 124. The output signal 126 can be provided to one or more external devices 150 for monitoring purposes (which external device(s) may be, for example, a laptop or other mobile computing device, or a remote server system).
Optionally, the device 100 may further comprise a transmitter 122, which is integral to the communication module and configured to transmit the output signal 126 from the communication module 102 via a wireless connection to the one or more external devices. The transmitter 122 may be a Bluetooth or other short range transmitter, or may be a long range transmitter. The transmitter 122 can communicate the output signal 126 to the external devices 150 using any suitable communication protocol. Transmitter 122 can be a transceiver, arranged to receive signals at communication module 102, for example from external device(s) 150.
In some example implementations, the switch-disconnector 100 comprises a second detection coil 110 disposed around the other of the first contact terminal 104 or the second contact terminal 106 in the same way as is discussed above. The second detection coil is configured to output a second signal 124 indicative of a current through the respective terminal. The communication module 102 is communicatively coupled to both detection coils 110 and is configured to receive the signals 124 from the contact terminals 104, 106 and output a signal 126 in dependence on the received signal and/or the received second signal. For example, the communication module 102 can provide the output signal 126 when one of the signals 124 indicates a predetermined criterion is satisfied, such as the current through one of the contact terminals exceeding a threshold. In another example, the communication module 102 can provide the output signal 126 based on processing of both the signals 124; for example, an average of signals 124 may be compared to predetermined threshold or used in another decision process, which approach may provide for a more resilient and robust device since minor measurement or detection errors can be at least partly mitigated against.
In some examples, the detection coil is a Rogowski coil, and the voltage value output by the detection coil 110 is proportional to a rate of change of current through the respective contact terminal. A Rogowski coil is an electrical device for measuring alternating current (AC) or high-speed current pulses, and consists of a helical coil of wire (without a ferromagnetic core) with the lead from one end returning through the centre of the coil to the other end (so that both terminals are at the same end of the coil). The Rogowski coil 110 is placed around the straight first contact terminal 104 to measure the current through the contact terminal. In some examples, the output 124 of the Rogowski coil can be connected to an electrical (or electronic) integrator circuit configured to determine the current through the respective contact terminal by integration of the signal proportional to a rate of change of current through the respective contact terminal. The communication module 102 can comprise such a circuit. The output signal 126 from the communication module can be a signal which is proportional to the current, or proportional to the rate of change of current, or can be any other signal produced in dependence on the signal 124 received from the detection coil 110.
The output signal 126 can thus be indicative of a current through one or both of the respective contact terminals, depending on the arrangement of detection coils 110. In some embodiments, the output signal is a warning signal indicating a current through the respective contact terminal satisfies a predetermined threshold. For example, the output signal 126 can indicate an overcurrent condition of the electrical circuit to which the switch-disconnector 100 is electrically connected to. The warning signal can be provided to a user for manual operation of the switch-disconnector. In other embodiments, the switch-disconnector can be designed to trip (perform a mechanism OFF operation based on an electrical/mechanical signal). In such disconnector mechanisms, output signal 126 can be received (either via a wired or wireless connection) by the actuating mechanism 114 or another component of the switch-disconnector; the actuating mechanism can be controlled, in dependence on the signal 126, to actuate the bridge contact to break the current conduction path. This approach can allow for improved overcurrent protection of electrical devices, since the time before isolation of the device may be reduced as compared to a manually actuated switch-disconnector.
In some embodiments, each switch-disconnector 100 may be associated with its own communication module 102, which can simplify the manufacture and assembly of the device. In the examples described herein, the communication module 102 is mounted to the front portion or face 112a of the housing 112 of the switch-disconnector 100. This mounting can be via a clip on or clip fit arrangement, or the communication module can be screwed to the front face 112a, or the mounting can by any other suitable means. By mounting the communication module 102 onto a front of the switch-disconnector 100, the height and width of the switch-disconnector is not increased, which can improve retrofitting of the system to existing switch-disconnectors (which may be placed in locations of a restricted size, or in banks where it is not possible to add additional modules to a top/bottom or side of the switch-disconnector). Moreover, by manufacturing the communication module as a removable component, the module 102 can be more easily retrofit.
In the examples illustrated in Figures 1 and 2, the communication module 102 is arranged to be mounted integral with the actuating mechanism 114; for example, rotary component 114a can be removed in order to place the communication module 102 on a front of the switch-disconnector housing 112, and then the rotary component can be connected to the actuating mechanism 114 through the communication module 102 (for example, the module may comprise one or more openings to accommodate the components of the actuating mechanism 114). The proximity of the communication module 102 to the detection coil 110 can reduce materials and costs in manufacturing, since shorter electrical connections and/or lower power transmitters can be used.
However, it will be understood that aspects of the communication module 102 described herein may be located remote from the switch-disconnector 100. For example, transmitter 122 may forward or transmit signal 124 to a central processing device (which can be one of external device(s) 150) without performing any processing; the central processing device may process the signal to determine the output signal 126. In this way, multiple switch-disconnectors 100 may be associated with a single processing device; this may reduce the amount of electronics required and so facilitate provision of a cheaper switch-disconnector, since only a single processing system for the received signals 124 is required.
Breaking of the electrical contact between the first 104 and second 106 contact terminals and the moveable bridge contact 108 when opening switch 142 can lead to formation of an arc between the ends of the bridge contact 108 and respective ends of the first and second conductor terminals 104, 106. This arc formation can occur whenever conductors physically separate from one another. However, the geometrical arrangement of the bridge contact 108 and respective ends of the first and second conductor terminals 104, 106 can facilitate a reduction in the duration of this electric arc (or arc discharge) by directing the arc away from the conducting contacts and towards a cooler region of the interior of the switch-disconnector housing 112. It is important to dissipate the arc effectively, since the high temperature environment created by the arc can destroy the electrical contacts. A switch-disconnector of a second aspect configured to reduce arc formation will now be discussed with reference to Figure 6 (Figures 6A and 6B), though the description herein can apply equally to the switch-disconnector of the first aspect.
In the switch-disconnector described herein, an end 104a of the first contact terminal 104 extends parallel to one end 108a of the bridge contact 108, as illustrated by extension lines 120a and 120b of Figure 6. Similarly, an end of the second contact terminal 106a extends parallel to the other end 108b of the bridge contact 108, as illustrated by extension lines 118a and 118b of Figure 6. Furthermore, the ends 108a, 108b of the bridge contact and the ends 104a, 106a of the first and second contact terminals are inclined away from the direction of movement 116 of the bridge contact 108. For example, end 108a of the bridge contact and end 104a of the first contact terminal are both inclined away from the direction of movement 116 of the bridge contact 108 by an angle α₁, and end 108b of the bridge contact and end 106a of the second contact terminal are both inclined away from the direction of movement 116 of the bridge contact 108 by an angle α₂.
In other words, the ends 108a, 108b of the bridge contact and the ends 104a, 106a of the first and second contact terminals extend at an angle relative to the direction of movement 116 of the bridge contact (each angle is defined as the angle between an axis extending parallel to the direction 116 and the direction of extension 118, 120 of the relevant contact end, as illustrated in Figure 6A). The angles α₁ and α₂ can be different from one another, or can be equal angles, a. Angles α₁ and α₂ can each be between 15 degrees and 75 degrees. Optionally, angles α₁ and α₂ can each be between 30 degrees and 60 degrees. Optionally, angles α₁ and α₂ are equal, and are both 45 degrees. In some examples when α₁, and α₂ are both 45 degrees, the contact terminals may form a "U" shaped portion, as described above, wherein the first and second bends 138, 140 are each arranged to be 90 degrees. The direction of extension of the ends of the 108a, 108b of the bridge contact and the ends 104a, 106a of the first and second contact terminals can thus be away from a front portion 112a of the housing.
The parallel extensions of the first/second contact terminal and the ends of the bridge contact 108 can facilitate a good contact between the different conducting components, improving the performance of the switch-disconnector 100. In some embodiments, good electrical contact can be facilitated by additional electrical contacts 132 disposed between the end 104a of the first contact terminal 104 and the end 108a of the bridge contact 108, and disposed between the end 106a of the second contact terminal 106 and the end 108b of the bridge contact 108.
By combining this parallel extension of contact ends with the inclination discussed above, the handling of arc formation can be improved without increasing a size of the switch-disconnector. In some particular implementations, as the bridge contact 108 moves along direction 116, the substantially "U" shaped path formed by the ends of the contact terminals and of the bridge contact (see e.g. the combination of components 108a, 104a and 132 of Figure 6B) provides a direction for the arc to travel in (rather than the arc remaining between the two contacts until its extinction) which is free from electrical contacts or other components. As the bridge contact 108 moves further along direction 116, this geometrical path arrangement drives the arc 134 away from the contacts along direction 136, effectively dissipating the arc whilst maintaining a compact switch-disconnector. Moreover, the symmetrical arrangement allows for effective arc dissipation, regardless of a direction of current flow through the current conduction path. A safer and more robust switch-disconnector may therefore be provided.
In some embodiments, vents or ventilation openings 130 may also be provided in the housing 112 to vent the hot air/gas created by the arc formation. These ventilation openings can be substantially aligned with the ends of the bridge contact (i.e. the ventilation is orientated substantially along lines of extension 118, 120, or along direction 136). Alternatively, these ventilation openings 130 can be inclined or bent away from this direction 136 by an angle β, optionally bent away at an obtuse angle β (β > 90°)optionally inclined away into a direction 152 perpendicular to the direction of movement of the bridge 116, in order to improve the efficacy of the venting. In particular, the arc is drawn towards the cooler region of the switch-disconnector 100, away from the contact ends 104a, 106a and 108a, 108b. A safer and more robust switch-disconnector may therefore be provided. Both these positions of vents 130 are shown in Figure 6A - it will be understood that the vents may be arranged symmetrically, or may be placed in different locations, for example one aligned along direction 136 and one along direction 152, as appropriate.
It is noted herein that while the above describes various examples of the isolating switch of the first aspect, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

A disconnector (100) comprising:
a switch, the switch comprising:
a first, fixed, contact terminal (104) of a first conductor,

a second, fixed, contact terminal (106) of a second conductor, and

a moveable bridge contact (108);

an actuating mechanism (114) configured to open and close the switch by actuation of the moveable bridge contact, wherein the actuating mechanism is configured to move the bridge contact in a direction (116) from a first position to a second position, wherein in the first position the switch is closed and the bridge contact is in electrical contact with the first and second contact terminals to define a current conduction path, and wherein in the second position the switch is open and the bridge contact is electrically separate from the first and second contact terminals;

a detection coil (110), the detection coil configured to output a signal (124) indicative of a current through the respective contact terminal;

a communication module (102) communicatively coupled to the detection coil and configured to receive the signal indicative of a current through the respective contact terminal and provide an output signal (126) in dependence on the received signal; and characterised in that said detection coil is disposed around the first contact terminal or the second contact terminal of the switch; the circuit breaker further comprising

a housing (112) comprising a front portion which is accessible to a user in normal use, wherein the switch is disposed within the housing and the communication module is external to the housing, and wherein:
the communication module is coupled to the front portion of the housing, and/or

the detection coil is accessible through the front of the housing.
The disconnector of any preceding claim, wherein the respective first or second contact terminal around which the detection coil is disposed comprises one or more angled portions.
The disconnector of claim 2, wherein the respective contact terminal comprises a "U" shaped portion having a first bend (138) and a second bend (140), and wherein the detection coil is disposed on the respective contact terminal between the first and second bends.
The disconnector of any preceding claim, wherein an end of the first contact terminal extends parallel to one end of the bridge contact and an end of the second contact terminal extends parallel to the other end of the bridge contact, and wherein the ends of the bridge contact and the ends of the first and second contact terminals are inclined away from the direction of movement of the bridge contact.
The disconnector of claim 4, wherein the ends of the bridge contact are inclined away from the direction of movement of the bridge contact by an angle, a;
optionally, wherein the angle, α, is between 15 degrees and 75 degrees, optionally wherein the angle is between 30 degrees and 60 degrees, optionally wherein the angle is 45 degrees.
The disconnector of any preceding claim, wherein the signal indicative of a current comprises a voltage value indicative of a current through the respective contact terminal.
The disconnector of claim 6, wherein the detection coil comprises a Rogowski coil and wherein the voltage value is proportional to a rate of change of current through the respective contact terminal.
The disconnector of claim 6 or claim 7, wherein the communication module is further configured to determine a current through the respective contact terminal based on the voltage value, and to output a signal in dependence on the determined current.
The disconnector of any preceding claim, wherein the detection coil is electrically connected to the communication module.
The disconnector of any preceding claim, wherein the communication module is a wireless communication module configured to wirelessly provide the output signal to one or more external devices.
The disconnector of claim 10, wherein the detection coil is electrically connected to a transmitter (122) of the communication module, the transmitter configured to wirelessly transmit the output signal from the communication module.
The disconnector of any preceding claim, wherein the actuating mechanism is automatically controlled, in dependence on the output signal, to actuate the bridge contact.
The disconnector of any preceding claim, wherein the output signal is indicative of a current through the respective contact terminal, optionally, wherein the output signal is a warning signal indicating a current through the respective contact terminal satisfies a predetermined threshold.
The disconnector of any preceding claim, wherein a second detection coil (110) is disposed around the other of the first contact terminal or the second contact terminal, the second detection coil configured to output a second signal indicative of a current through the respective contact terminal, and wherein the communication module is communicatively coupled to the second detection coil and is configured to receive the second signal and output a signal in dependence on the received signal and/or the received second signal.
An electrical apparatus comprising the disconnector of any preceding claim.