GB2589714A

GB2589714A - Switch

Info

Publication number: GB2589714A
Application number: GB2014529.8A
Authority: GB
Inventors: Clifford-Smith Richard
Original assignee: Ash Wireless Electronics
Current assignee: Ash Wireless Electronics
Priority date: 2019-11-05
Filing date: 2020-09-15
Publication date: 2021-06-09
Also published as: GB202014529D0; GB201916072D0

Abstract

A switch comprises: a first contact 111 that is moveable relative to a second contact 133,135 to make or break an electrical connection. First contact 121 has a taper 113 and the second contact has a second taper 123. The two tapers together engage in a mated configuration to define a taper that can be self-holding and that makes the electrical connection. One taper can be a male taper having a frusto-conical portion and the other can be a female taper. An actuator can move the contacts relative to each other and can be: a piston (fig 11, 515) and cylinder; a rotating cam (fig 11, 415); a varying ratio linkage (fig 9, 313); or an electromagnetic actuator comprising coils (fig 5, 211,213) that move an impactor such as slide hammer 219 sliding on an armature 215 against a first stop to close the contacts and a second stop 117 to open the contacts. First taper 113 can make or break an electrical connection between first 133 and second 135 contact portions of the second contact, the portions having an insulator or gap 131 between them. The two contact portions 133,135 and insulator 131 can be clamped together by an insulating frame.

Description

SWITCH

FIELD OF THE INVENTION

The present invention relates to a switch, and to a method of operating a switch.

BACKGROUND

Electrical switchgear is used in power distribution (for example in relays and contactors) and is responsible for making and breaking contacts between electrical circuits. it is desirable for a switch to operate rapidly, and to have a low contact resistance when the switch is closed.

SUMMARY

According to the invention, there is provided a switch, comprising: a first contact and a second contact, wherein the first contact is moveable relative to the second contact to make or break an electrical connection between the first and second contact; wherein the first contact comprises a first taper, the second contact comprises a second taper, the first and second taper together defining a taper that engages in a mated configuration to make the electrical connection.

The taper enables an increased contact force between the first and second contact, and a high contact area, reducing contact resistance and enabling high currents to be handled by the switch.

The first and second taper may together define a self-holding taper that engages in a mated configuration to make the electrical connection. A self-holding taper enables a bi-stable switch configuration, with the switch biased the open position, but also stable in the closed position due to the self-holding taper. In addition, the self-holding taper produces high interfacial forces between the tapers when engaged, resulting in reduced contact resistance.

The first taper may be a male taper, and the second taper may be a female taper. The male tape may have reduced mass compared with the female taper/socket, which may enable faster switching.

The first taper is a female taper, and the second taper is a male taper. A stationary male taper and moveable female taper may be particularly advantageous in the context of a split second contact (described below in more detail).

The male taper may comprise a frusto-conical portion. The circular cross section of a frusto-conical taper provides a large contact area, and results in a self-centring engagement.

The switch may further comprise an actuator configured to move the first contact relative to the second contact to make or break an electrical connection between the first contact and the second contact. The actuator may be electrically operated.

The actuator may comprise an impactor configured make or break a connection between the first contact and the second contact by impact. An impactor is an elegant way to provide high forces over a short duration that are particularly suitable for disengagement of a taper (and engagement).

The actuator may comprise a slide hammer, the slide hammer comprising: the impactor; an armature connected to the first contact, along with the impactor is configured to slide; a first stop, configured to receive an impact from the impactor to make an electrical connection between the first contact and the second contact; a second stop. configured to receive an impact from the impactor to break an electrical connection between the first contact and the second contact.

The first stop and impactor may be configured to provide a lower impact stiffness than the second stop and so that, for a specific amount of impact momentum, the impactor striking the first stop will cause a smaller peak force than the impactor striking the second stop. This difference in force between engagement and disengagement may improve the reliability of disengagement of the tapers by the impactor.

The first stop may comprise a buffer configured to reduce the peak force resulting from an impact between the first stop and the impactor.

The buffer may comprise a compressible washer. The buffer may be placed on either the impactor or the first stop The actuator may be an electromagnetic actuator.

The actuator may comprise a drive coil configured to drive the first contact towards the second contact and a retract coil configured to separate the first contact from the second contact.

The drive coil and retract coil may act to move the impactor, and the impactor may act to make or break an electrical connection between the first and second contact.

The drive coil and retract coil may be configured to drive a different type of actuator element than the impactor.

The switch may comprise an alternative actuator, operated in a different way (for example, pyrotechnic actuator, hydraulic actuator or pneumatic actuator).

The actuator may comprise a linkage, the linkage having a drivable input and an output coupled to the first contact. The linkage may have a motion ratio that varies between contact make and contact break positions of the first and second contacts.

For example, the actuator may comprise a four-bar linkage. The actuator may comprise a toggle clamp-type arrangement. The output of the linkage may be configured to apply a clamping force to the moving contact to push the moving contact into a mated configuration with the other contact. A toggle clamp-type arrangement may be provided for each contact where each contact is moveable.

Where both the first and second contacts are moveable, a linkage may be provided coupled to each contact. The linkage may be driven, and motion of the linkage may be transferred to the first contact (or second contact where both contacts are moveable).

The actuator may have a motion ratio that varies over actuation from a first position to a second position. The motion ratio is the ratio of movement between an input of the linkage (i.e. a driven part of the linkage) and an output of the linkage (i.e. coupled to the contact). For example, the input of the linkage may move more quickly than the output of the linkage, or vice versa.

The first position may be a contact break position -the contacts may be 'open i.e. the first and second contacts may not be in electrical communication.

The second position may be a contact make position -the contacts may be 'closed', i.e. the first and second contacts may be in electrical communication.

The actuator may comprise a cam arrangement, comprising a cam configured to actuate the first contact and a shaft on which the cam is configured to rotate, wherein the cam is configured to place the first contact into electrical communication with the second contact in a first orientation and wherein the cam is configured to cause or allow the first contact to break electrical communication from the second contact in a second orientation.

The cam arrangement may act like a continuously-variable-transmission and allow for the moving contact to move at high velocity with low force over part of its travel but high force with lesser velocity over the portion of travel where the first and second tapers are mated. In this way, the actuator comprising the cam arrangement may have a variable motion ratio as with the linkage described above.

The cam arrangement may include a follower, movement of which is driven by the cam, and the follower may be in communication with the first contact to operate the contact. The cam may be arranged in communication with the first contact directly to drive movement of the contact. In some examples, both contacts are moveable and a cam arrangement may be provided to operate each contact.

As with the impactor above, these example actuators may not be operated by the drive and retract coils and may otherwise be electromagnetically, electrically or mechanically operated, for example The actuator may comprise a pyrotechnically driven approach, e.g. use of commercially available firearms blanks to actuate the switch via a piston and cylinder arrangement. The actuator may comprise a piston and cylinder, wherein the piston is coupled to the first contact and configured to operate the first contact.

The pyrotechnic actuator may optionally additionally be used with the impactor approach, the linkage or the cam approach, giving both the advantage of much higher speed of operation. Any example actuators described herein may be used to drive another of the example actuators, for example.

Where each of the first and second contacts are moveable, each contact may be operated differently. Any of the example actuators may be used in combination -for example, the first contact may be operated by an impactor and the second contact may be operated by a linkage.

The second contact may include an electrically insulating portion or gap arranged between a first and second electrically conducting portion, the insulating portion or gap electrically insulating the first and second electrically conducting portions from one another. The first contact may be configured to: establish electrical contact between the first electrically conducting portion and the second electrically conducting portion when the first and second tapers are engaged in a mated configuration, and break an electrical connection between the first electrically conducting portion and the sccond electrically conducting portion when the first and second tapers are disengaged from the mated configuration.

The switch may further comprise a frame configured to retain the first and second electrically conducting portions in contact with the insulating portion, or to maintain a specific gap between the first and second electrically conducting portions.

The frame may comprise a first insulating plate in contact with the first electrically conducting portion and a second insulating plate in contact with the second electrically conducting portion, the first insulating plate and second insulating plate clamped about the second contact so as to secure the first electrically, conducting portion and second electrically conducting portion in position.

A taper angle of the first and second taper may be 7 degrees or less (half cone angle). Such a taper angle is generally self-holding (for typical contact materials). The taper angle may be less than 5 degrees, less than 3 degrees or less than 1.5 degrees. There is a compromise between contact forces and the required actuation distance to open and close the switch (with a sufficient contact gap to stand-off the current).

The taper angle may exceed 7 degrees, where self-holding (also known as self-locking) of the taper may not be necessary or desirable -for example, where the actuator comprises a cam arrangement or is otherwise configured to hold the tapers in place. A greater taper angle (i.e. above 7 degrees) may be beneficial in height-restricted designs of the switch.

The switch may further comprise an arc reduction system configured to reduce arcing between the first and second contact. The arc reduction may comprise a semiconductor switch connected in parallel with the mechanical switching arrangement formed by the first and second contact.

The semiconductor switch may comprise a triac and/or one or more thyristors, and may be configured to short circuit the first and second contact as the first and second contact move to engage or separate.

DETAILED DESCRIPTION

Examples embodiments will be described, with reference to the accompanying drawings, in which: Figure 1 is a sectional view of a switch according to an embodiment; Figure 2 illustrates a taper angle and parameters of a taper; Figure 3 is a sectional view of a further switch, comprising a split second contact; Figures 4 and 5 are sectional views of the switch of Figure 3 including an actuator, respectively in an open and closed condition; Figure 6 is an alternative exploded view of the switch of Figures 3 to 5, excluding actuator coils; Figures 7 and 8 are sectional views of a switch in which the second (stationary) contact comprises a male taper; Figure 9 shows an alternative actuator according to an example; Figure 10 shows an alternative actuator according to an example; and Figure 11 shows an alternative actuator according to an example.

Referring to Figure 1, a switch 101 is shown, comprising a first contact 111 and a second contact 121. The first contact 111 is moveable (vertically in the example embodiment) relative to the second contact 112 to make or break an electrical connection between the first contact 111 and the second contact 112. When the first contact 111 is touching the second contact 112, there is an electrical connection between the first contact 111 and 112, and when the first and second contact 111, 112 are separated, the electrical connection is broken The first contact 111 comprises a first taper 113. In this embodiment the first taper 113 of thc first (moveable) contact is a male taper. Sidcwalls of the male taper 113 arc angled with respect to a longitudinal axis of the male taper 113. In other embodiments (see Figures 7 and 8) the first taper 113 may instead be a female taper that is moveable to engage and disengage with a male taper of the second contact 121.

The first taper 113 is preferably frusto-conical, and tapers with the narrow end facing thc second contact 121. In othcr embodiments, other taper geometries may bc uscd (e.g. wedge taper, square taper, etc).

The second contact 121 comprises a second taper 123 configured to mate with the first taper 113 (i.e. with the respective sidewalls of the first taper and second taper substantially parallel). in this example the first taper 113 is male, and the second taper 123 consequently comprises a female taper defining a socket that is configured to receive the male taper in a mating configuration.

The tapering geometry of the first and second contact 111, 121 results in an enhancement of contact force between the contacting surfaces thereof, as well as providing a large surface area of contact. The high contact forces between large surface areas of the first and second contact 111, 121 result in reduced contact resistance, thereby increasing the current capacity of the switch 101. Furthermore, embodiments provide rapid switching, for example on a millisecond timescale, which is suitable for use in circuit breakers and load switching.

The switch 101 may be part of an electrical circuit, in use, in which electrical connection between the first and second contacts 111,121 completes the circuit and allows current to flow. Conductors (e.g. wires) 151, 161 form electrical connections to the respective contacts 111, 121. In the example of Figure 1, conductor 151 may be flexible, so as to accommodate movement of the first contact 111.

Embodiments may be configured for low voltage (<I kV), medium voltage (> kV and <75kV (and high voltage (>751(V) switching. The switch 101 may be configured to provide part of switchgear in a power system, and may be configured to protect electrical equipment (e.g. as part of a consumer unit or distribution board). The switch 101 may, for example, form part of a switchgear and transformer fine up.

The first and/or second contact 111, 121 may comprise copper, silver, copper alloy, silver alloy or another suitable electrical conducting material (such a material preferably comprising the contacting faces of the tapers).

An actuator (e.g. an electromagnetic actuator, such as a solenoid) may be provided to move the first contact Ill. The switch 101 may be configured to detect a fault condition (e.g. a residual current or an overcurrent) and automatically actuate the first contact 111 to break an electrical connection between the first and second contact 111, 121 in response to the fault condition. The switch 101 may be manually operable (as an alternative, or in addition to electromagnetic actuation).

The first contact 111 may be connected to a stem 115. The stem 115 may be used to move and/or retain the first contact 111 in a position with respect to the second contact 121. For example, the stem 115 may be in communication with an actuator. An illustrative example of this will be described with reference to Figures 4 and 5.

The female taper 123 may define a cavity or socket 125 with an opening 127 for receiving the male taper 113. The male taper 113 may have a length that is equal or substantially equal to the length of the female taper 123, in certain embodiments, the male and female tapers 113,123 together define a self-holding taper (i.c one that requires a force to overcome the friction of engagement before there is any relative movement between the first and second contacts 111, 121). Example self-holding tapers are Morse tapers and Jacobs tapers -these arc widely used in machine tool couplings for transmitting rotational mechanical power. The angle required for a self-holding taper depends on the co-efficient of friction of the surfaces thereof, but as a general rule, a (half-cone) taper angle of 7 degrees or less will result in a self-holding taper.

The male taper 113 has a major diameter and a minor diameter, at the larger and smaller ends of the taper respectively. The female taper 123 may have the same major diameter and minor diameters as the male taper 113.

The taper angle (in degrees or radians) may be calculated using the taper T, from the following equations: T (D-d)/L (1) A = arctan(0.5T) (2) where D = larger diameter. d = smaller diameter. L is taper length and A is taper angle. These dimensions are illustrated in Figure 2.

The male and female tapers 113, 123 may have a taper angle of less than 5 degrees, less than 3 degrees or less than 1.5 degrees.

The male taper 113 and female taper 123 may be defined by a substantially solid material layer that is at least 2mm thick (or at least 3mm, or 5mm, or lOmm thick). It should be understood that the interlocking tapers of the present invention are not formed from one or more elements mounted on a spring-loaded elastic member for transverse movement (like a banana plug), but are defined from a substantially solid material.

In the embodiment of Figure 1, movement of the first contact III results in movement of the conductor 151. In some circumstances, it may be desirable for the conductors 151, 161 not to be required to accommodate movement or deformation when the switch is operated.

Figure 3 shows an example embodiment in which the second contact 121 is split by an electrically insulating portion 131, so that there is a first electrically conducting portion 133 on one side of the electrically insulating portion 131 and a second electrically conducting portion 135 on the other side of the electrically insulating portion 131. In other embodiments, the first and second electrically conducting portions 133, 135 may be separated by a gap 131, and the first and second electrically conducting portions supported at the required separation to define the taper by an external frame. The first and second electrically conducting portion 133, 135 together define the female taper 123 for receiving the male taper 113 of the first contact 111.

Conductors 151 and 161 are connected to the first and second conducting portion 133, 135 respectively. When the male taper 113 of the first contact 111 is not in contact with the female taper 123 of both the first and second conducting portion 133, 135 of the second contact 121, there is no electrical contact between conductors 151, 161.

When the male taper 113 is engaged with the female taper 123, electrical current can flow between the conductors 151, 161, via the contact that is made between the first and second conducting portions 133, 135 by the male taper 113 of the first contact 111 The appropriate separation between the first and second conducting portions 133, 135 depend on the voltage that the switch is required to isolate, and the breakdown field for the material separating the first and second conducting portions. Higher voltages will require higher standoff distances, or materials with higher breakdown fields.

The split second contact 121 allows the conductors 151, 161 to remain stationary while the switch 101 is opened and closed, which may improve reliability of the switch.

As discussed above, movement of the first contact 111 may be controlled using an actuator. The actuator may be coupled to the first contact 111 -for example at the stem 115 or the head 117 -and may be configured to drive the first contact 111 mechanically. in the embodiment of Figure 3, the stem 115 comprises a flange 117 at the head of the stem 115, which may be useful for actuation.

Figures 4 and 5 show a sectional view of a further switch 101 according to an embodiment, comprising an actuator 211. In this example there are many elements in common with Figure 3, and these will not be described and labelled again for concision, but it should be understood that elements common to Figure 3 operate in the same way as described with reference to Figure 3, and like reference numerals will consequently be used in this description. In Figure 4 the switch 201 is open with no electrical connection between conductors 151 and 161, and in Figure 5 the switch 201 is closed, forming an electrical connection between conductors 151, 161.

The actuator 211 is an electromagnetic actuator, comprising a drive coil 213 and retract coil 215 enclosing the stem 115 of the first contact III. The coils 213, 215 each form an annular winding around the stem 115 The actuator 211 further comprises an impactor 219, which is an annular element that encloses the stem 115. The stem 115 forms an armature along which the impactor 219 slides. The impactor 219 is configured to strike a surface of the taper 113 at one end of its stroke, and to strike a surface of the flange 117 at the head of the stem 115 at the other end of its stroke. The impactor 219 striking the taper 113 will cause the male taper 113 to engage with the female taper 123 and create a low contact resistance (due to high contact forces and large surface area contact). The impactor 219 striking the flange 117 will disengage the male taper 113 from the female taper 123, opening the switch contacts. A biasing means (e.g. a spring) may be provided to hold the first contact 111 in the open switch position (disengaged from the second contact 121).

The impactor 219 forms a slide hammer arrangement (with the stem 115, male taper 113 and flange 117), in which the impactor 219 is actuated by the drive coil 213 and retract coil 215. The drive coil 213 is configured to drive the impactor 219 to strike a surface of the male taper 113 to engage the tapers (and close the switch), and the retract coil 215 is configured to drive the impactor 217 to impact the flange 117 to disengage the tapers (and open the switch).

In order to ensure that the impactor 219 is capable of disengaging the tapers, the switch may be configured to cause a peak force from the impactor 219 engaging the tapers to be lower than a peak force from the impactor 219 disengaging the tapers. One way to do this is to provide an impact interface for engagement that has reduced contact stiffness than an impact interface for disengagement. An impact interface that is stiff will result in higher peak forces (with shorter duration) as a result of an impact. A compressible washer (e.g. a spring washer) on the impact face of the taper 113 may be used to reduce peak forces from the impactor 219 striking the taper 113 to engage the switch.

In Figures 4 and 5 a frame is shown around the second contact 121, which may be used to maintain the first conducting portion 133 and second conducting portion 135 at the appropriate separation to form the female taper, and assist with reacting the engagement forces of the tapers (which will urge elements forming the female taper apart). The frame comprises insulating plates 171, 172, which may be clamped around the second contact 121 (by fasteners for example bolts, which are not shown in Figures 4 and 5).

Figure 6 shows an alternative (exploded) view of the embodiment of Figures 4 and 5 with the coils removed, in which the frusto-conical shape of the taper 113 is more clearly shown.

Figures 7 and 8 show a switch according to an embodiment in which the first (moveable) contact 111 comprises a female taper 113, and the second (stationary) contact 121 comprises a male taper 123. The second contact 121 comprises a first and second conducting portion 133, 135, separated by a non-conducting portion 131, as in the embodiment of Figures 3, 4, and S. and operates in a similar way. in this embodiment, the interfacial forces resulting from engagement of the tapers 113, 123 will tend to urge the conducting portions 133, 135 together. Furthermore, magnetic forces arising from current through the switch will tend to expand the male taper in the socket/female taper, thereby keeping contact resistance low.

Figure 9 shows an alternative actuator 311. Figures 9, 10 and 11 show the first and second contacts 111,121 and features thereof, some of which are not labelled for concision.

The actuator 311 comprises a linkage 313 in communication with the first (moveable) contact 111. The linkage 313 may include an input link 315 configured to be driven. The linkage 313 may include an output link 317 communicatively coupled to the first contact 111. The input link 315 and the output link 317 may be connected by a hinged joint (revolute) or a sliding joint (prismatic) or another suitable joint. The input link 315 and output link 317 may be connected by way of one or more further links (for example, the linkage 313 may be a four-bar linkage), and connection may be by a hinged, sliding or other joint.

The output link 317 may be configured to apply a clamping force to the first contact 111 in the manner of a toggle clamp.

The input link 315 may be mechanically or electrically driven, for example driven by a motor. The input link 315 may be hydraulically or pneumatically driven, for example. The input link 315 may be driven electromagnetically, for example by drive and retract coils as discussed above or by an electric motor. As the input link 315 is driven, motion may be transferred to the output link 317 and so to the first contact 111.

The output link 317 may be configured to drive the first contact 11 I and to retract the first contact 111. For example, the output link 317 may be configured to press the first contact 111 into a mating configuration with the second contact 121 and, at another time, to pull the first contact 111 away from the second contact 121. The pulling force exerted by the output link 317 on the first contact 111 may overcome the self-hold of the tapers 113,123 in order to break contact.

The linkage 313 may have a motion ratio that varies over actuation. The motion ratio may be defined as the instantaneous ratio of movement of the input link 315 and the output link 317, with a motion ratio >1 meaning that there is more movement at the output link 317 than the input link 315.

The linkage 317 may be configured with a low motion ratio (effectively providing high leverage for the actuator) when the tapers 113,123 are in the mated configuration, compared with a higher motion ratio (effectively providing high movement velocity for the contact 111 and low leverage for the actuator) as the tapers are separated. The higher force may be sufficient to overcome the self-hold of the tapers 113,123.

Figure 10 shows an alternative actuator 411. The actuator 411 comprises a cam arrangement 413, comprising a cam 415 and shaft 417. The cam 413 may be arranged to make direct physical contact with the first contact 111 to drive the contact 111 -as shown in Figure 10 -or the cam arrangement 413 may further comprise a follower (not shown) which may be in communication with the first contact 111 and configured to transfer motion to the first contact 111. The cam 413 is shown having a generally circular shaped cross-section, with an eccentric pivot (but other forms, including teardrop shaped, may be used). The cam 413 may be any suitable shape for driving the first contact 111 towards the second contact 121 and allowing the first contact 111 to retract, as the cam 413 rotates about the shaft 417.

The first contact 111 may be spring-loaded or otherwise biased to return to a contact break position (as shown in Figure 10 -where the tapers 113,123 are not mated).

Where a follower is provided, the follower may be biased in order to retract the first contact 111 when the cam 415 is not pressing the first contact 111 into the mated configuration.

As with the actuator 313 described above, the cam arrangement 413 may be driven mechanically or electrically, hydraulically or pneumatically, for example. The cam arrangement 413 may be driven by a motor, which may be configured to drive rotation of the shaft 417.

Figure 11 shows an alternative actuator 511. The actuator 511 comprises a piston arrangement 513, comprising a piston 515 and a cylinder 517. The piston 515 may be coupled to the first contact 111; for example, the piston 515 may be attached to the first contact 111 or integrally formed with the first contact 111. The piston 515 may be configured to push and pull the first contact I 11. The piston 515 may be configured to drive movement of the first contact 111 towards the mated configuration. The piston 515 may be configured to pull the first contact 111 to retract the first contact 111 from the mated configuration. The pulling force exerted by the piston 515 on the first contact 111 may be sufficient to overcome the self-hold of the tapers 113,123.

The actuator 511 may comprise a pyrotechnic actuator, for example a Metron actuator from Chemring Energetics UK.

Where the actuator or part of the actuator contacts the first contact 111 (for example, the cam 413), insulation may be provided the prevent electrical conduction between the first contact 111 and the actuator. For example, the stem 115 and/or head 117 may be formed from an electrical insulator or otherwise be electrically insulating, for example by way of a coating. The actuator may be electrically insulated to prevent conduction between the actuator and the first contact 111. The same applies for the second contact 121 in examples where both the first and second contacts 111,121 are actuated.

Breaking contact when a current is flowing may result in an arc between the first and second contacts. In some embodiments, the switch may be configured to switch AC currents during a zero crossing of the current, so as to substantially prevent arcing. Provided the switch contacts separate in a few milliseconds (e.g. less than 5ms), this will effectively mitigate arcing (for a typical AC frequency of 50Hz or 60Hz). An alternative approach for mitigation of arcing (which may otherwise result in contact wear and reduced switch lifetime) is to use a semiconductor switch in parallel with the switch. As the switch opens or closes, the semiconductor switch may be placed in a conducting condition, so that any arc between the contacts of the mechanical switch is extinguished due to the conducting path through the semiconductor switch. Since the semiconductor switch is conducting only for a very small amount of time (corresponding with the opening or closing of the switch), it is typically able to deal with currents in excess of those it would be capable of accommodating in steady state conditions.

In some embodiments, the switch may be configured to switch DC currents. The switch may be used in parallel with a semiconductor switch as described above, which may be an insulated gate bipolar transistor (TGBT) for switching DC currents. More than one IGBT may be used in parallel with the switch.

Although specific embodiments have been described, it will be appreciated that other variations are possible, and the scope of the invention should be determined with reference to the appended claims.

Claims

CLAIMSA switch, comprising: a first contact and a second contact, wherein the first contact is moveable relative to the second contact to make or break an electrical connection between the first and second contact; wherein the first contact comprises a first taper, the second contact comprises a second taper, the first and second taper together defining a taper that engages in a mated configuration to make the electrical connection.
2. The switch of claim 1, wherein the first and second taper together define a self-holding taper that engages in a mated configuration to make the electrical connection.
3. The switch of claim 1 or 2, wherein the first taper is a male taper, and the second taper is a female taper.
4. The switch of claim 1 or 2 wherein the first taper is a female taper, and the second taper is a male taper.
5. The switch of claim 3 or 4, wherein the male taper comprises a frusto-conical portion.
6. The switch of any preceding claim, further comprising an actuator configured to move the first contact relative to the second contact to make or break an electrical connection between the first contact and the second contact.
7. The switch of claim 6, wherein the actuator comprises an impactor configured make or break a connection between the first contact and the second contact by 30 impact
8. The switch of claim 7, wherein the actuator comprises a slide hammer, the slide hammer comprising: the impactor; an armature connected to the first contact, along with the impactor is configured to slide; a first stop, configured to receive an impact from the impactor to make an electric& connection between the first contact and the second contact; a second stop, configured to receive an impact from the impactor to break an electrical connection between the first contact and the second contact.
9. The switch of claim 8, wherein the first stop and impactor are configured to provide a lower impact stiffness than the second stop and so that, for a specific amount of impact momentum, the impactor striking the first stop will cause a smaller peak force than the impactor striking the second stop.
10. The switch of claim 7, wherein the first stop comprises a buffer configured to reduce the peak force resulting from an impact between the first stop and the 15 impactor.
11. The switch of claim 10, wherein the buffer comprises a compressible washer.
12. The switch of any of claims 6 to 11, wherein the actuator is an electromagnetic 20 actuator.
13. The switch of claim 12, wherein the actuator comprises a drive coil configured to drive the first contact towards the second contact and a retract coil configured to separate the first contact from the second contact.
14. The switch of claim 13, including the subject matter of any of claims 8 to 11, wherein the drive coil and retract coil act to move the impactor, and the impactor acts to make or break an electrical connection between the first and second contact
15. The switch of claim 6, wherein the actuator comprises a linkage, the linkage having a drivable input and an output coupled to the first contact, wherein the linkage has a motion ratio that varies between contact make and contact break positions of the first and second contacts.
16. The switch of claim 6, wherein the actuator comprises a cam arrangement, comprising a cam configured to operate the first contact and a shaft on which the cam is configured to rotate, wherein the cam is configured to place the first contact into electrical communication with the second contact in a first orientation and wherein the cam is configured to allow the first contact to break electrical communication from the second contact in a second orientation
17. The switch of claim 6, wherein the actuator comprises a piston and cylinder, wherein the piston is coupled to the first contact and configured to operate the first contact.
18. The switch of any preceding claim, wherein the second contact includes an electrically insulating portion or gap arranged between a first and second electrically conducting portion, the insulating portion or gap electrically insulating the first and second electrically conducting portions from one another, and the first contact is configured to: establish electrical contact between the first electrically conducting portion and the second electrically conducting portion when the first and second tapers are engaged in a mated configuration, and break an electrical connection between the first electrically conducting portion and the second electrically conducting portion when the first and second tapers are disengaged from the mated configuration.
19. The switch of claim 18, further comprising a frame configured to retain the first and second electrically conducting portions in contact with the insulating portion, or to maintain a specific gap between the first and second electrically conducting portions.
20. The switch of claim 19, wherein the frame comprises a first insulating plate in contact with the first electrically conducting portion and a second insulating plate in contact with the second electrically conducting portion, the first insulating plate and second insulating plate clamped about the second contact so as to secure the first electrically conducting portion and second electrically conducting portion in contact with the electrically insulating portion.
21. The switch of any preceding claim, wherein a taper angle of the first and second taper is 7 degrees or less.
22. The switch of claim 21, wherein a taper angle of the first and second taper is 5 degrees or less.
23. The switch of any preceding claint further comprising an arc reduction system connected in parallel with the first and second contact, the arc reduction system configured to reduce arcing between the first and second contact.
24. The switch of claim 23, wherein the arc reduction system comprises a semiconductor switch, configured to short circuit the first and second contact as the first and second contact move to engage or separate.