GB2561219A

GB2561219A - Electrical Terminal

Info

Publication number: GB2561219A
Application number: GB1705551.8A
Authority: GB
Inventors: Singhal Sanjaya; Kumar Pawan; Sardana Sanjeev
Original assignee: Secure International Holdings Pte Ltd; Secure Int Holdings Pte Ltd
Current assignee: Secure International Holdings Pte Ltd; Secure Int Holdings Pte Ltd
Priority date: 2017-04-06
Filing date: 2017-04-06
Publication date: 2018-10-10
Anticipated expiration: 2037-04-06
Also published as: GB201705551D0; GB2561219B

Abstract

An electrical terminal includes a locking mechanism such as a movable cage 150, an actuator such as a spring 145, and a holding mechanism such as a nylon screw 155. The locking mechanism is held in an unclamped position allowing easy insertion of a conductor 135. The holding mechanism is then released, and the locking mechanism moves under the force of the actuator to clamp the conductor. This prevents removal of the electric cable conductor, creating a tamper proof configuration post installation. It also reduces the likelihood of a poor electrical connection forming between the electrical cable conductor and the current busbar as a result of an incorrect or poor quality installation. The terminal may be used on an electrical meter, where it may allow the load and supply terminals to be one over the other.

Description

(54) Title of the Invention: Electrical Terminal Abstract Title: Electrical terminal (57) An electrical terminal includes a locking mechanism such as a movable cage 150, an actuator such as a spring 145, and a holding mechanism such as a nylon screw 155. The locking mechanism is held in an unclamped position allowing easy insertion of a conductor 135. The holding mechanism is then released, and the locking mechanism moves under the force of the actuator to clamp the conductor. This prevents removal of the electric cable conductor, creating a tamper proof configuration post installation. It also reduces the likelihood of a poor electrical connection forming between the electrical cable conductor and the current busbar as a result of an incorrect or poor quality installation. The terminal may be used on an electrical meter, where it may allow the load and supply terminals to be one over the other.

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FIG. 5

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Before wire clamping

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FIG. 6

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FIG. 9

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After wire clamping

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FIG. 10

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Electrical Terminal

Field of invention

The invention relates to an electrical terminal, especially an electricity meter terminal for an electricity meter, the terminal comprising a cable locking device.

Background

Electrical terminals with contact elements made as tension springs, often called tension spring terminals, have been used for decades in industrial connection technology. In addition, electrical terminals with a screw-type terminal have been used for decades. The clamping principle for tension spring terminals is similar to that of screw technology. While in screw-type terminals a tension sleeve pulls the lead against a conductor bar by actuating the clamping screw, for a tension spring terminal this task can be assumed by a tension spring bent into a loop shape. The pretensioned tension spring is opened with an actuating tool, such as a screwdriver, so that the lead can be inserted into a through opening in the clamping leg of the tension spring into the terminal space. After removing the actuating tool, the lead is pulled by spring force against the conductor bar, which adjoins the contact leg of the tension spring.

One modification of the above described tension spring terminals is represented by electrical terminals with at least one strain-relief clamp connection as a spring force clamping terminal. With these electrical terminals, based on the special configuration of the strain-relief clamp connection, electric leads with a relatively large cross section of preferably 35 mm² to 150 mm²can be connected. In contrast, generally leads with cross sections of 1.5 mm², 2.5 mm², 4 mm², 6 mm², and 10 mm² to 35 mm², and those with special configurations, are connected to normal tension spring terminals. Since higher currents can be transmitted via electric leads with a larger cross section, electrical terminals made for connecting to leads with a large cross section are often also called high current terminals.

High current terminals are made both with a screw-type terminal and with a spring force clamping terminal. The high clamping forces of the screw-type terminal or spring force clamping terminal are achieved in the prior art by the respective clamping terminals, i.e. the contact element, which is designed to be thicker, extending from the electrical terminals for connection of normal leads. However, since high current terminals must also be manually actuated for opening the clamping sites against the respective clamping force of the clamping terminal, maximization of the type of construction of conventional terminals is limited, since lead cross sections starting with 50 mm² often require excessive handling forces.

Electrical terminals for use as high current terminals have been developed that have strainrelief clamp connections, which consist of a generally U-shaped strain-relief clamp and a compression spring. The compression spring is located in the strain-relief clamp such that it pulls or biases the bottom end of the strain-relief clamp against the bottom of a conductor bar that extends through openings in the clamping leg of the strain relief clamp. By this, an electric lead inserted through the through opening in the clamping leg of the strain-relief clamp is clamped fast against the bottom of the conductor bar. In electrical terminals designed for leads with large cross sections, the clamping site of this strain-relief clamp connection, for which the compression spring must be axially compressed, can only be opened using support measures.

One known electrical terminal is disclosed in DE 198 17 924 C2. In this high current terminal, the actuating element for opening and closing the strain-relief clamp connection is a feed rotation cylinder, which is supported in the insulating housing above the strain-relief clamp and coaxially with the compression spring of the strain-relief clamp connection. The rotation cylinder has an outside thread so that it can be screwed into an inside thread formed on the insulating housing by means of a rotary tool that can be axially inserted into the cylinder. When the feed rotation cylinder is screwed in, the strain-relief clamp is pressed against the compression spring. The compression spring is thus compressed, by which the strain-relief clamp connection is opened so that an electric lead to be connected can be inserted between the lower edge of the through opening in the clamping leg of the tension spring and the conductor bar.

US20070141910 A1 discloses an electrical terminal including an insulating housing, a conductor bar, strain-relief clamp connections and actuating elements located in the insulating housing for opening and closing the strain-relief clamp connections. The electrical terminal enables manual opening of the clamping site even when the strain-relief clamp connection is designed for leads with large cross section since the actuation element is made as an actuating cam that is eccentrically supported in the insulating housing. The actuating cam can be pivoted by an actuating tool out of a first position in which the strain-relief clamp connection is closed into a second position in which the strain-relief clamp connection is opened so that an electric lead can be inserted between the conductor bar and a through opening in the strain relief clamp connection.

These traditional terminal arrangements come with several drawbacks. The ability to alternate a clamp between an open and closed position enables users to alter the connections of “supply side” cables with an intention to tamper. This is especially an issue in the case of electricity meters, where users may attempt to conceal their utility usage. A drawback with screw type terminals is that the installation process can take time, and unless the screws are tightened properly, there can be a risk of terminal heating, potentially leading to a fire. Typically the width of electric terminal cannot be smaller than the space required by the terminals in a row, which limits its compactness.

Summary of the Invention

An object of embodiments of this invention is for an electrical terminal that once installed, provides a permanent clamp on an electrical cable conductor in contact with a current busbar. This prevents removal of the electric cable conductor, creating a tamper proof configuration post installation. It also reduces the likelihood of a poor electrical connection forming between the electrical cable conductor and the current busbar as a result of an incorrect or poor quality installation.

In a first aspect, the present invention provides an electrical terminal according to appended claim 1.

In one embodiment, the electrical terminal includes an insulating housing comprising at least one current busbar at least partially within the insulating housing, at least one first electrical cable termination point at which an electrical coupling is formed, also within the insulating housing and comprising a cable insertion opening for inserting an electrical cable conductor for electrical connection. Within the insulating housing is also a clamping mechanism comprising an actuation opening, an actuation spring, a locking mechanism and a holding mechanism. The electrical cable conductor is positioned adjacent to and parallel with the current busbar within the locking mechanism such that the spring force of the actuation spring is in a direction perpendicular to the length of both the electrical cable conductor and the current busbar. The locking mechanism is held against a holding structure via the holding mechanism opposing the spring force of the actuation spring. The locking mechanism is configured so that upon release of the holding mechanism, the locking mechanism moves into the actuation opening, permanently clamping the electrical cable conductor onto the current busbar due to the spring force of the actuation spring.

The holding mechanism can comprise an actuation element. Embodiments of the holding mechanism take on a variety of forms, including a holding screw, a holding pin, or a holding latch. The holding mechanism may be characterised such that it can be released from outside of the insulating housing, thus maintaining an insulating barrier between the electrical components within the electrical terminal and the installing personnel. The position of the holding mechanism within the terminal also influences its effectiveness. The holding mechanism may be positioned such that the majority of the component of the force on the holding mechanism opposing the spring force is parallel with the spring force. This reduces the force on the holding mechanism due to the spring force of the actuation spring prior to its release, reducing the required size and/or strength from the holding mechanism and therefore reducing the size and cost of the resultant electrical terminal.

The actuation spring within the electrical terminal can also form a variety of embodiments, including but not limited to a compression spring, extension spring, or torsion spring. The spring force acts in a direction substantially perpendicular to the length of both the electrical cable conductor and the current busbar. This ensures an effective contact between the electrical cable conductor and the current busbar. It will be apparent to the skilled person with the benefit of this disclosure that the position of the actuation spring within the insulating housing can vary whilst continuing to provide this function, and depends on the type of actuation spring used.

The electrical terminal can include embodiments consisting of primary and secondary termination points electrically connected via the current busbar which provides a current path between two sets of electric cable conductors. In this embodiment, the at least one first cable termination point is the primary termination point. The sets of electric cables can include either a set of load or a set of supply cables. In this embodiment, the primary and secondary termination points can both be configured as the permanent clamping mechanism termination described above. Conversely the embodiment can be configured such that the primary termination point is configured as the permanent clamping mechanism termination described above, with the secondary termination point is configured as a removable termination. An example of a removable termination could include a conventional screw type terminal or strainrelief type terminal.

A further alternative embodiment can include an electrical terminal comprising only primary electrical cable terminations points within the electrical terminal, wherein the current busbar is in direct electrical connection to the load or a main busbar, an example of which includes but is not limited to transformer, motor or generator terminations, a distribution board busbar or switchboard busbar. The use of this embodiment extends to any electrical cable termination where a permanent fixture is desirable.

In one embodiment, a method of connecting an electrical cable conductor to an electrical terminal is provided, comprising: receiving an electric cable conductor into a first cable termination point, through a first cable insertion opening, the opening being provided in an insulator housing for the terminal, releasing a holding mechanism, so as to cause a locking mechanism that is in cooperation with the holding mechanism to clamp the electric cable conductor onto a current busbar due to the a force of an actuation spring that cooperates with the locking mechanism. The holding mechanism may comprise a holding member such a screw that can be accessed from outside the housing can be moved such that movement of the screw causes the locking mechanism to clamp the electric cable conductor on the current busbar.

The method can be adapted from the aforementioned method for embodiments in which the electric terminal comprises primary and secondary termination points electrically connected via the current busbar, providing a current path between two sets of electric cable conductors, wherein the first cable termination point is the primary termination point, wherein an electric cable set is a set of either supply or load cables, to further comprise, installing the primary termination points using the aforementioned method, followed by then installing the secondary termination points using the aforementioned method.

The method can be adapted for embodiments in which the electric terminal comprises primary and secondary termination points electrically connected via the current busbar, providing a current path between two sets of electric cable conductors, wherein the first cable termination point is the primary termination point, wherein an electric cable set is a set of either supply or load cables, wherein the primary termination point is configured as the permanent clamping mechanism termination described above, wherein the secondary termination point is configured as a removable termination, to further comprise, installing the primary termination points using the original method, then inserting an electric cable conductor into a secondary cable termination point, through a secondary cable insertion opening. Then apply a removable holding mechanism, so as to clamp the electric cable conductor onto the current busbar until the removable holding mechanism is released to remove the cable. Where terminals comprise of multiple secondary cable termination points, repeat the previous steps for each for each termination point.

In a second aspect, the present invention provides an electricity meter comprising means for monitoring the consumption of electricity and at least one aforementioned electrical terminal.

In a third aspect, the present invention provides an electrical relay comprising at least one aforementioned terminal and a means for disconnecting a supply side cable termination from a load side cable termination.

Brief Description of the Drawings

Embodiments of the present invention are now described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic showing a size cutaway view of an electricity meter that comprises an electrical terminal according to an embodiment, where an electrical conductor is clamped within the terminal (after clamping);

FIG. 2 is a schematic of a clamping mechanism for a primary electrical cable termination point prior to the release of the locking mechanism (before clamping);

FIG. 2a, 2b are schematics of a holding mechanism used in the clamping mechanism of Fig. 2; FIG. 3 is a schematic view of an example locking cage that forms part of the locking mechanism of the terminal in Fig. 1 and Fig. 2;

FIG. 3a is a schematic view of a permanent clamping mechanism for the primary electrical cable termination point prior to the release of the locking mechanism (before clamping);

FIG. 3b is a schematic view of the permanent clamping mechanism of Fig. 3a following the release of the locking mechanism (after clamping);

FIG. 4 is a schematic of the primary electrical cable termination point of Fig. 2 within a terminal insulating housing prior to the release of the locking mechanism (before clamping);

FIG. 5 is a schematic view of the electricity meter of Fig. 1 with electrical conductors inserted but not yet clamped in a plurality of electrical terminals in the meter;

FIG. 6 shows a view of one terminal in the bottom section of the meter in figure 5 from the front of the meter, a side view of the terminal, and a cross section taken along line A-A;

FIG. 7 is a schematic of the primary electrical cable termination point after the release of the locking mechanism (clamped);

FIG. 8 is a schematic of the primary electrical cable termination point of Fig. 5 within an insulating housing after the release of the locking mechanism (clamped);

FIG. 9 is a schematic view of an electricity meter of Fig. 1 with electrical conductors inserted and clamped in a plurality of electrical terminals in the meter;

FIG. 10 shows a view of one terminal in the bottom section of the meter in figure 9 from the front of the meter, a side view of the terminal, and a cross section taken along line B-B; and

FIG. 11 is a perspective schematic of an electricity meter from below showing an electrical terminal block that comprises a plurality of electrical terminals.

Detailed Description of Embodiments

FIG. 1 shows an electrical terminal 100 located within an electricity meter 105, the terminal 100 being located in an electrical terminal block insulating housing 110 positioned at a bottom section of the electricity meter 105. A top section of the electricity meter comprises electronics including a detector (not shown) for monitoring the consumption of electricity and the functionality of the top section of an electricity meter will be known to those in the art and will not be described in detail here. In particular, the features housed in the top section of the electricity meter and relating to how the meter detects consumption of electricity are conventional and will not be described in detail here. The inventors have arrived at an advantageous arrangement for connecting one or more cables to an electricity meter as will be described in more detail below. It will be appreciated that although the embodiments are described in relation to an electricity meter, the terminal could be adapted for use in other products with the benefit of the disclosure herein with the necessary changes having been made.

Contained inside the insulating housing 110, is a current busbar 115 which is a form of electrical conductor comprising a conductor bar having a conductive body, and a holding structure 120. The busbar 115 is fixedly attached to the holding structure 120. Note that the busbar 115 may instead be attached to another fixed part of the terminal. Also within the insulating housing 110, is a primary electrical cable termination point for each primary electrical cable 125 termination, comprising a primary electrical cable insertion opening 130 for inserting a primary electrical cable conductor 135, an actuation opening 140, an actuator which in this embodiment is an actuation spring 145, a locking mechanism comprising a locking cage 150 and a holding mechanism 155. The locking cage 150 is spring-loaded in the sense that it cooperates with the spring 145 and can be kept in a locked position based on the spring position. Movement of the spring will cause movement of the cage 150. The locking cage 150 can move relative to the fixed current busbar 115 and holding structure 120. The insulating housing 110 further contains a secondary termination point for each secondary electrical cable 160 termination, comprising a secondary electrical cable insertion opening 165 for inserting a secondary electrical cable conductor 170 and a removable fastening mechanism 175. Both the primary electrical cable termination point and the secondary electrical cable termination point are electrically connected via the current busbar 115.

As shown in the figures 2 and 4-6, when the primary electrical cable 125 is inserted through the primary cable insertion opening 130, it is positioned adjacent to and parallel with the current busbar 115. The actuation spring 145 in this embodiment is a compression spring located between the current busbar 115 and the locking cage 150, and positioned such that the spring force is acting in a direction substantially perpendicular to the longitudinal axis or length of one of or both the primary cable conductor 135, and the current busbar 115. The holding mechanism in this embodiment comprises a holding screw 155 which is preferably nonconductive (made from nylon, for example) located between the holding structure 120 and the locking cage 150 to hold a section of the locking cage that is distal from the spring 145 adjacent to the holding structure 120 until released. The holding screw 155 can be released via the holding mechanism release 180 located outside the electrical terminal block insulating housing

110. An appropriate release instrument such as a screwdriver can be used to release the holding screw 155.

As illustrated in the embodiment of FIG. 2a, 2b the holding screw 155 consists of three portions; the head portion 155a, the body portion 155b and the base portion 155c. The head portion 155a is distal to a first end of the body portion 155b and consists of a disk with a trenchlike depression across the diameter of one face of the disk, such that it resembles the features of a flat-head screw. It is this portion of the holding screw 155 that acts as the holding mechanism release 180, and is accessible from outside the insulator housing 110. The body portion 155b of the holding screw 155 is a cylinder extending from the head portion 155a to the base portion 155c, wherein its length is at least equal to the combined thickness of both the holding structure 120 and the locking mechanism 150. That is, the combined thickness of the side walls of the holding structure 120 and locking mechanism 150 that receive the screw 155. The base portion 155c is distal to a second end of the body portion 155b and consists of a rectangular plate, the plate having at least a portion protruding out past the width of the body portion 155b. It will be appreciated that geometries other than rectangular plates may be used (e.g. elliptical plate). It will also be appreciated that other designs of the holding screw may be used to cooperate with the locking mechanism to provide the holding functionality described herein. The screw could instead be a form of hook to attach to a surface of locking mechanism in the unlocked position and to release from the surface in the locked position.

As shown in FIG. 4, the electrical terminal 100 has an insulator housing 185 and a plurality of insulating housings can form the electrical terminal block insulating housing 110 (see FIG. 5 and 11, for example, where four insulating housings 185 of an electricity meter are shown). Once released, the locking cage 150 moves in direction X (shown in FIG. 2) and within the actuation opening 140 created by the holding structure 120. In this embodiment, direction X is substantially perpendicular to the longitudinal axis of the conductor 135 and bus bar 115. The openings (described in more detail below) in the locking cage 150 that correspond substantially to the openings in the holding structure 120 through which the cable conductor 135 is located, clamp the conductor 135 to the bus bar 115. Once released, the cage 150 is locked in the locking position and cannot be reset without destruction to the terminal thus providing a permanent clamping mechanism for the supply side cables 125 in the electricity meter.

The locking mechanism in this embodiment comprises a locking cage 150 such as that shown in more detail in FIG. 3. Once released, the cage 150 is forced away from the holding structure 120 and into the actuation opening 140, clamping the primary electrical cable conductor 135 down onto the current busbar 115, as shown in FIGs. 7 to 10.

Referring to FIG. 3, the locking cage 150 that is part of the locking mechanism according to this embodiment is shown and described in more detail. The dimension and size of the various aspects of the cage are not shown to scale but drawn for ease of explanation.

In this embodiment, the cage 150 has two parallel sides 151, 152 that are parallel to sides of the holding structure 120 and can slide within the holding structure 120. The cage 150 includes one or more openings that are through holes at various locations in the cage 150. The cage 150 is formed from a plate-like member that may be a single unitary member that has been bent to form the cage 150 or may be formed of a plurality of members joined (e.g. welded) to form the shape of the cage 150.

Each of the sides 151, 152 have openings 151a, 152a that are arranged to receive the electrical cable conductor 135 and the current busbar 115 (see FIG. 2, for example). The opening 151a has dimensions that are at least the thickness and width of the current busbar 115, and the diameter of conductor 13 but slightly larger so that one edge (such as a top edge) of the opening 151a can clamp one side of the conductor 135 onto the busbar 115 after the holding mechanism release 180 is activated. Similarly, the opening 152a has dimensions that are at least the thickness and width of the current busbar 115, and the diameter of conductor 13 but slightly larger so that one edge of the opening 152a can clamp one side of the conductor 135 onto the busbar 115 after the holding mechanism release 180 is activated. It will be appreciated that the openings 151a, 152a in this embodiment are axially aligned but the skilled person will appreciate with the benefit of this disclosure that other relative arrangements may be provided.

In this embodiment, the side 151 is connected, at one end, to an oblique section 153 of the cage 150 that is at an angle to the side 151. Section 153 has an opening 153a, the opening 153a having dimensions such that in a certain orientation the base portion 155c of the holding screw 155 fits through said opening, but in other orientations, does not. The embodiment illustrated in FIG. 3 includes the opening 153a that matches the shape of the base portion 155c of the holding mechanism 155. This has the advantage of preventing rotation of the holding screw 155 while the base portion 155c is located within the opening 153a (eg. when the locking cage 150 is in the locked position). The other end of the side 151 is connected to a bottom section 154 that connects to the parallel side walls 151, 152. Although reference is made to connections between 151, 152, 153, 154, it will be appreciated that these could be bends in the single unitary member as mentioned above rather than identifiable connections.

The embodiment illustrated in FIG. 2 and 3 shows a curved portion on the edge of openings 151a, 152a nearest face 153. This is to create a larger contact area around the cable when the locking mechanism is in the clamping position. The skilled person will appreciate with the benefit of this disclosure that other relative arrangements may be provided. In addition, although a cage is referred to in this embodiment, other constructions could be provided to permanently lock a conductor in a terminal.

FIG. 3a, 3b illustrate the operation of the permanent clamping mechanism. The locking cage 150 is in a first, unstable, unlocked position in Fig. 3a. It is unstable in the sense that the locking cage is held by the holding mechanism against the force of the spring. This is the position that the locking cage is arranged at manufacture when cable conductors have not been placed in the meter. Once a conductor 135 is inserted in an opening in the clamping mechanism such that it is adjacent the current busbar 115, the holding screw 155 is released by rotating the head portion 90 degrees (a quarter turn of the holding mechanism) and the base portion of the holding screw 155 fits through opening 153a in the locking mechanism 150. Upon release of the holding screw 155, the actuation spring 145 expands into its more stable position, forcing the locking cage 150 away from the holding structure 120 and into the actuation opening 140. The locking cage 150 moves away from the holding structure until the locking mechanism openings 151a and 152a make contact with the primary cable conductor 135, clamping it onto the current busbar 115. With the locking cage in this second, stable, locked position, in which the conductor 135 in direct contact with the conductive body of the current busbar 115, the spring 145 provides a force on one side of the bus bar (the side opposite to where the conductor 135 is located) which is turn can provide a better clamping connection between the busbar 115 and the conductor 135. Once the locking cage is in its second, locked position, the holding mechanism cannot be reset (without destroying thel terminal). The locking cage of the locking mechanism is therefore unidirectional by allowing for only a singular movement from a first unlocked position to a second locked position but not the reverse. In this way, a permanent clamping mechanism can be provided.

In other embodiments, the holding mechanism may be operated differently to lock the locking mechanism depending on the configuration of the holding mechanism (for example, more or less than a quarter turn of the screw to release the holding mechanism).

Other embodiments of the locking mechanism 150 can exist that perform the same function. An alternative embodiment includes replacing the locking cage for a locking plate with a compression spring between the locking plate and the holding structure. Once the holding mechanism 155 is released, the locking plate would be forced down onto the primary electrical cable conductor 135, clamping it to the current busbar 115.

In other embodiments different types of actuation springs 145 can be used in a variety of different positions within the primary electrical cable termination point, so long as they are positioned such that the spring force is acting in a direction perpendicular to the length of both the primary cable conductor 135, and the current busbar 115.

In other embodiments various types of holding mechanisms 155 can be used, so long as they perform the function of holding the locking mechanism 150 adjacent to the holding structure 120 until released. An example of this is replacing the holding screw for a holding pin or a holding latch. Although the type and positions of the holding mechanism 155 can vary between embodiments, by positioning the holding mechanism 155 such that the majority of the component of the force on the holding mechanism opposing the spring force is parallel with the spring force, the force acting on the holding mechanism 155 will be minimized. This has the effect of reducing the required size and/or strength of the holding mechanism 155.

FIG. 1 and 11 shows the secondary termination point for each of the secondary electrical cable 160 terminations. As shown particularly in figure 1, when the secondary electrical cable conductor 170 is inserted through the secondary cable insertion opening 165, it is positioned substantially parallel with the part of current busbar 115 that cooperates with the conductor 135 and in front of the current busbar 115 when looking from the front of the meter 105. Once inserted, the secondary electrical cable conductor 170 is connected to another part of the current busbar 115 via a removable fastening mechanism 175 to ensure an effective electrical connection is made. In this embodiment, the removable fastening mechanism 175 is a screw type termination. Other embodiments include replacing the screw type terminal for a strainrelief clamp terminal or any other removable terminal, for example. An extension of the illustrated embodiment of FIG. 1 is an electrical terminal where both the primary and secondary electrical cable termination points use the permanent clamping mechanism termination. This will ensure that once installed, all electrical cable terminations are permanent and no tampering with the electrical terminal is possible.

The arrangement of the embodiment illustrated in FIG. 1 is such that the load and supply side terminals are positioned one over the other, thereby allowing the meter width to be much smaller than traditional connections. This arrangement includes the further advantage of obscuring access to the holding mechanism release 180 at the supply side terminals post installation, making the terminals further tamper proof.

A further alternative embodiment includes an electrical terminal comprising only primary electrical cable 125 terminations points within the electrical terminal, wherein the current busbar is in direct electrical connection to the load or a main busbar, an example of which includes but is not limited to transformer, motor or generator terminations, a distribution board busbar or switchboard busbar.

Although an actuation spring is referred to in embodiments herein, it will be appreciated that other equivalent actuators (eg. pneumatic) could be provided to provide a locking force on the cable to permanently clamp the conductor of an electrical cable.

It will be appreciated that although a 3-phase electricity meter is described and shown in the embodiments discussed herein, it will be appreciated that a different number of supply side and or load side terminals may be provided depending on the type of meter. For example, there may be two incoming (supply side) terminals for live and neutral and two outgoing (load or consumer side) terminals for neutral and live.

In embodiments of a 3-phase electricity meter 105 as described, the supply side cables 125 can be permanently installed for example by an energy installation engineer with a low likelihood of tampering due to the permanent secure nature of the connection with the cable using the electrical terminal 100. The releasable load side cables 160 can be installed separately at a later time and are located parallel and above a respective load side cable when viewing the electricity meter from the front. Figure 1 shows a side view but it would be clear that if viewed from the front of the meter 105, the conductor portion 170 of the load side cable 160 is located parallel and above the conductor portion 135 of the supply side cable 125 (also see figure 8 which shows a clamped supply side cable 125 and the opening 165 to receive a load side cable - not shown in fig. 8 - and figure 11 which shows the respective insertions openings for the supply side and load side cables). If viewed from the bottom of the meter, the supply side insertion openings 130 are positioned in a row along an imaginary x-axis and the load side insertion openings 165 are positioned in a row set back in the a y-axis direction from the from the supply side insertion opening 130 and above respective supply side insertion openings 130 (in a z-axis direction. The terminal configuration can provide a more compact meter compared to, for example, conventional arrangements where all of the supply side and load side openings are in a single row.

As is also evident from figure 1 and 11 for example, when the load side cable 160 is positioned within a load side cable insertion opening 165, access to the holding mechanism release 180 is prevented as the release is concealed by the cable 160. The release 180 is located between the load side cable insertion opening 165 and the supply side cable insertion opening 130.

It will be appreciated that the electrical terminal may be provided in an electrical relay (not shown) which includes a means for disconnecting a supply side cable termination from a load side cable termination. Similarly to a meter, the relay has the supply side and load side terminations. However, the relay comprises the disconnecting mechanism (conventional) as oppose to the electricity consumption monitoring or measuring means of a utility meter. Therefore, the electrical terminal can be used in many types of devices but is particularly suited to a utility meter such as an electricity meter.

Numerous modifications, adaptations and variations to the embodiments described herein will become apparent to a person skilled in the art having the benefit of the present disclosure, and such modifications, adaptations and variations that result in additional embodiments of the present invention are also within the scope of the accompanying claims.

Claims

1. An electrical terminal, comprising:

at least one first electrical conductor;

a conductor insertion opening for receiving a second electrical conductor for connection with the first electrical conductor, a clamping mechanism, comprising: an actuation means;

a unidirectional locking mechanism cooperating with the actuation means and comprising means for clamping the second electrical conductor to the first electrical conductor based on the position of the actuation means, and a holding mechanism comprising means for releasably holding the clamping means in a first, unclamped position, whereby in use, the locking mechanism is configured such that upon release of the holding mechanism, the clamping means moves to a second, clamped position through cooperation with the actuation means thereby clamping the electrical second conductor onto the first electrical conductor and remaining in the second, clamped position.

2. The electrical terminal as claimed in claim 1, wherein the clamping mechanism further comprises an actuation opening and, in use, upon release of the holding mechanism, the clamping means moves into the actuation opening to clamp the second electrical conductor onto the first electrical conductor.

3. The electrical terminal as claimed in claim 1 or 2, wherein the spring force of the actuation spring is in a direction substantially perpendicular to the length of at least one of the second electrical conductor and the first electrical conductor.

4. The electrical terminal as claimed in any one of claims 1, 2, or 3 wherein terminal comprises an insulating housing and the holding mechanism is releasable from outside the insulating housing.

5. The electrical terminal as claimed in any preceding claim, wherein the holding mechanism is positioned such that the majority of the component of the force on the holding mechanism opposing the spring force is parallel with the spring force.

6. The electrical terminal as claimed in any preceding claim, wherein the holding mechanism includes any one of a holding screw, a holding pin or a holding latch.

7. The electrical terminal as claimed in any preceding claim, further comprising a holding structure that is fixedly positioned relative to the locking mechanism that is movable with respect to the holding structure.

8. The electrical terminal as claimed in any preceding claim, wherein the locking mechanism comprises a locking cage.

9. The electrical terminal as claimed in any preceding claim, wherein the actuation means comprises an actuation spring.

10. The electrical terminal as claimed in claim 9, wherein the actuation spring is a compression spring.

11. The electrical terminal as claimed in claim 10, wherein the compression spring is located within the locking mechanism.

12. The electrical terminal as claimed in any of claims 1 to 11, wherein the spring is located between the locking mechanism and the holding structure.

13. The electrical terminal as claimed in any one of claims 1 to 9, wherein the actuation spring is an extension spring.

14. The electrical terminal as claimed in claim 13, wherein the extension spring is located outside the locking mechanism.

15. The electrical terminal of any preceding claim wherein the first electrical conductor is a current busbar.

16. An electricity meter comprising means for monitoring the consumption of electricity and at least one electrical terminal according to any preceding claim.

17. The electricity meter of claim 16 comprising supply side and load side cable terminations electrically connected via the first electrical conductor, providing a current path between the second electrical conductor acting as the supply side conductor and a load side conductor.

18. The electricity meter as claimed in claim 17, wherein the the supply side termination is arranged to receive a supply cable and the load side termination is arranged to receive a load cable.

19. The electricity meter as claimed in claim 18, wherein the supply side cable termination includes a supply side cable insertion opening and the load side cable termination includes a load side insertion opening, wherein the load side insertion opening is positioned above the supply side cable insertion opening when viewed from below the meter.

20. The electricity meter as claimed in claim 19, wherein the load side insertion opening is positioned above the supply side cable insertion opening when viewed from below the meter and set back from the supply side cable insertion opening.

21. The electricity meter as claimed in any of claims 16 to 20, wherein meter is a three phase meter and there are four electrical terminals arranged in a row to form a terminal block arrangement.

22. The electricity meter as claimed in any of claims 17 to 21 wherein the load side termination is configured as a removable termination.

23. The electricity meter as claimed in claim 22, wherein a removable termination is a screw type termination or a strain-relief type termination.

24. The electricity meter as claimed in any of claims 16 to 23, wherein the monitoring means is coupled to the first electrical conductor in order to monitor the consumption of electricity.

5

25. An electrical relay comprising an electrical terminal according to any of claims 1 to

15, and means for disconnecting a supply side cable termination from a load side cable termination.

26. An electrical terminal, an electricity meter or electrical relay as hereinbefore

10 described with reference to the attached drawings.