GB2531157A

GB2531157A - Cut-out assembly

Info

Publication number: GB2531157A
Application number: GB1516755.4A
Authority: GB
Inventors: Mennell Thomas
Original assignee: Schneider Electric Ltd
Current assignee: Schneider Electric Ltd
Priority date: 2014-10-07
Filing date: 2015-09-22
Publication date: 2016-04-13
Anticipated expiration: 2035-09-22
Also published as: GB201417713D0; GB2531157B; GB201516755D0

Abstract

A cut-out assembly 1 for use in an electricity distribution network comprises a housing 2 and a meter 17 attached to the housing. The housing includes a number of input terminals for connecting to single phase inputs of an electricity supply, and a number of output terminals for connecting to cables of a consumer electricity network. A current flow path between each of the input and output terminals includes a fuse and a current transformer. An output from the current transformer is fed to the meter. The cut-out assembly provides a compact device which incorporates all the necessary protection for metering and fuse protection. The components are able to be arranged within the housing so that the assembly has a significantly reduced height, thereby providing improved access for both incoming and outgoing cables.

Description

CUT-OUT ASSEMBLY

The present invention relates to a cut-out assembly, particularly, although not exclusively for use in electricity distribution networks with an electricity supply of greater than bOA.

Typically, in electricity supply networks where the supply is larger than 100 amps the supply provides a three-phase supply. The electricity supplier usually provides a three-phase cut-out incorporating fuse protection for the supply, and a point of isolation at the place of connection to a consumer's electricity network. Metering to measure the energy consumed is usually installed adjacent to the cut-out. This provides a measure of the electricity that is consumed by the consumer which is then billed to the consumer.

For practical reasons electricity meters are usually current transformer operated rather than being directly connected as is typical for supplies below 100 amps. Historically, the current transformers have been located in a separate enclosure with all the necessary connections to connect to the cut-out device and customer cables. This separate housing or enclosure is usually mounted directly above the cut-out device.

Meters are usually mounted on the hinged door of the current transformer housing. In addition, all the necessary fuses for protection of the meter and the test links to facilitate ready replacement of the meter for any reason, including calibration, are housed in the current transformer enclosure or located on the hinged door.

In some instances the cut-out device and the current transformer housing may be attached separately to a convenient wall or they may be provided as single unit on a suitable wall and/or floor mounting frame.

Electricity supply cables normally enter the cut-out at the bottom of the unit and the cables connecting the supply to the customer's network enter the top of the current transformer housing. Cables may approach the unit horizontally or vertically.

This conventional arrangement leads to a number of difficulties. The cut-out device and the current transformer housing are often tall and, as a result, limit the access for cables particularly when the cables approach horizontally.

If the cut-out device and meter housing are supplied as a single unit they are often heavy, large and difficult to handle particularly in confined spaces with limited access. Often, several people are required to locate the unit in its installed position.

If the cut-out and current transformer housing are supplied separately, different people are often required to install the different pieces of equipment. This is expensive and often results in multiple visits to the site being required over a period.

According to the present invention, there is provided a cut-out assembly for use in an electricity distribution network, the assembly comprising a cut-out housing and an electricity meter mounted on the cut-out housing, the cut-out assembly including a plurality of input terminals for connecting to single phase inputs of an electricity supply, a plurality of output terminals for connecting to cables of a consumer electricity network, a plurality of connecting members defining a current flow path between each one of the input terminals and a respective one of the output terminals, and a plurality of current transformers provided in at least one of the defined current flow paths to provide a transformed current to the electricity meter in response to current flow in the at least one of the defined current flow paths, with only one current transformer in any one current flow path, wherein the input terminals, output terminals, connecting members and the current transformer are provided within the cut-out housing.

The cut-out assembly may include a plurality of fuses provided in at least one of the defined current flow paths.

The current transformer may be provided in the at least one defined current flow path between the respective fuse in the defined current flow path and the respective output terminal. Alternatively, the current transformer may be provided in the at least one defined current flow path between the respective fuse in the defined current flow path and the respective input terminal.

The current transformer may be a toroidal current transfonner arranged around one of the connecting members of the respective defined current flow path.

The connecting members may include a pair of pins, one pair per current flow path, and configured for connection to respective terminals of the fuse, The connecting members may further include a further connector, connected between one pain of each pair of pins and a respective output terminal. The further connector may be a Y-shaped connector or an elongate connector.

The connecting members may further include a bridging connector connected between a two connecting plates.

The cut out housing may include a plurality of compartments, each compartment housing a selection of the plurality of connecting members such that there is defined a single current flow path between each one of the input terminals and a respective one of the output terminals in each compartment.

One or more of the compartments may include one of the current transformers.

The cut out housing may include a cover and the cut out housing may comprise a front portion and a rear portion.

The meter may be mounted on a meter housing, the meter housing being attached to the cut-out housing. The meter housing may house the required circuitry for coupling the output from the current transformer and a voltage from the current flow path to the meter.

The required circuitry may include meter voltage supply protection fuses, a unit incorporating current transfonner shorting links, secondary meter voltage supply protection fuses and terminals for connections to the meter. The meter voltage supply protection fuses may be supported within the meter housing by first support brackets. The unit may be supported by second support brackets.

The current transformer shorting links are configured to bridge the connections between the current transformer and the meter so as to short circuit the transformer.

The meter housing may include a front cover upon which the meter is housed. The meter may be hingedly mounted on the meter housing. The meter housing may include a pair of brackets to hold the cover in a closed position. The pair of brackets may include an anti-tamper seal.

The advantages of the present invention are a cut-out assembly which provides a compact device which incorporates all the necessary protection for metering and fuse protection.

The components are able to be arranged within the housing so that the assembly has a significantly reduced height, thereby providing improved access for both incoming and outgoing cables. It requires less space and has a significantly reduced mass that is much more readily handled into confined spaces.

By providing shortage links between the output circuitry from the current transformer, the meter can be removed without disrupting the power supply.

The invention will now be described, by way of example only with reference to the accompanying figures of which: Figure 1 is an isometric view of the cut-out assembly of the present invention; Figure 2 is an exploded view of the cut-out assembly of Figure 1; Figure 3 is an isometric view of the front portion of the housing of the cut-out assembly of Figure 2; Figure 4 is an isometric view of the rear portion of the housing of the cut-out assembly of Figure 2; Figure 5 is an isometric view of the assembly of Figure 1 including the meter and meter housing and the rear portion of the housing of Figure 4 showing the location of pairs of collinear pins, connecting members and current transformers; Figure 6 is a further isometric view of the assembly of Figure 1 but without the front cover on the housing; Figure 7 is a front view of the cut-out of assembly of Figure 1 without the cover in place; Figure 8 is a plan view of the cut-out assembly of Figure 1 in the direction of arrow VIII in Figure 7; is Figure 9is a side view of the cut-out assembly of Figure 1 in the direction of arrow IX in Figure 7; Figure 10 is a cross-section along the line A-A' of Figure 7; Figure 11 is a cross-section along the line B-B' of Figure 7; Figure 12 is an exploded view of the fuse holder for use in the cut-out assembly of Figure I; and Figure 13 is a circuit diagram of the cut-out assembly as integrated into an electricity supply network.

It should be noted that, for clarity, in Figures ito 12, not all parts of indicated in every Figure.

A cut-out assembly 1 comprises a housing 2 with a cover 3, into which the electricity supply cables (not shown) can be fed, and which are connected to the outgoing cables for a customer's supply. A meter 17 mounted on a meter housing 34 is attached to the housing 2.

The housing 2 has four adjacent longitudinally-extending compartments 4, 4' having substantially the same configuration.

The main body 5 of the housing 2 is made from two portions -a front portion 6 and a rear portion 7-shaped and configured to define the compartments 4,4'. The front and rear portions 6, 7 are detachable to allow access to the compartments 4, 4'.

Figure 3, illustrating the housing 2, does not include all features in all compartments 4, for clarity.

Each compartment 4, 4' has apertures 8 at each end to allow the electricity supply cables to be fed to, and out of, the compartments 4, 4'. Each compartment 4, 4' is provided with additional internal walls 9 for strength and to separate each phase and the neutral line from each other. Threaded screw holes 10 are provided to receive screw fort securing the front portion 6 to the rear portion 7.

Three of the compartments 4 are for the single phase input lines Ll, L2, L3 from the electricity supply and the fourth of the compartments 4' is for the neutral line, N. The outer face 11 of the front portion 6 of the main body 5 has a plurality of rectangular-shaped cavities 13, 13' defined by walls 12 extending from the outer face 11. There is one cavity 13, 13' for each compartment 4, 4'. Three of the cavities 13 have a pair of collinear longitudinal apertures 14, 15 in the outer face 11. In a fourth cavity 13', which corresponds to the fourth compartment 4', there is a single longitudinal slit 18 is provided intheouterface 11.

The three of the cavities 13 are configured to receive a fuse holder 30 in which is retained a fuse 16. Two opposing walls of the walls 12 include slots 46 which are used for cooling air to pass over the Ibse 16.

The fuse holder 30 has a body 51 with fuse mounts 49 into which the terminals 50 of the fuse are secured so that the fuse 16 is held in place, but can be manually removed. The fuse holder body 51 is configured to provide a handle portion 52 so that an operator can manually remove the fuse holder 30 to access the fuse 16 for replacement as required.

The fuse mounts 49 includes a fuse retention assembly 59a, 59b, 59c that secures the terminals 50 to the fuse body 51.

In this regard, the cavities 13, 13' and the fuse holder 30 are substantially similar to those of the Merlin Germ Shielded Heavy Duty Cutout TM manufactured and sold by Schneider Electric Limited and, as such, are known in the art and need not be described in any details herein.

Internally of the housing 2, within the compartments 4,4', an arrangement of connecting members 19, 20, 21, 25, 26, 27, made from an electrically-conducting material, are provided.

Specifically, the connecting members include pairs of collinear pins 19, 20 -one pair in each of the three of the compartments 4. The pins 19, 20 are aligned along an axis parallel to the longitudinal axis X of the compartment 4 and extend outwards of the compartment 4 in a direction substantially perpendicularly to longitudinal axis X. When the housing 2 is assembled, the pins 19,20 extend through a respective one of the pair of collinear longitudinal apertures 14, 15 and into the respective cavity 13.

The connecting members also include further connectors for connecting the proximal ends of one pin of the pairs of pins to consumer output terminals 22a.

The further connector may be a Y-shaped member 21, with the proximal end of the one pin 19 of the pair of pins 19 being retained within a recess 46 defined by the Y-shaped member 21. The other end of the Y-shaped member 21 is connected to the pair of consumer output terminals 22a.

The consumer output terminals 22a each comprise an aperture 23 and screw 24. The consumer output terminals 22a can be provided in pairs, or singly, and are used to connect the electricity supply cables (not shown) for a consumer's electricity supply. Such terminals are known to person skilled in the art.

As an alternative, the further connector may be a single elongate connecter 25 instead of the Y-shaped member 21, which is then connected to a single consumer output connector 22a. This is illustrated in Figure 2. Two of the compartments 4 are provided with a pair of consumer output terminal 22a and a Y-shaped member 21, and a third compartment 4 is provided with a single elongate connector 25 and one consumer output terminal 22a.

This provides an option of one or two consumer output terminals 22a for customer cables per phase and neutral, as two cables per phase are sometimes used in parallel to increase the current carrying capacity of the cables Different terminals are used for single and parallel cable arrangements.

As described above with regard to Figure 2 in which the two consumer output terminals 22a where two parallel cables are used and in the third of the compartment 4 a single elongate connector 25 is used for a single cable. The type of consumer output terminal 22a used is determined by the size of cable to be terminated and customer preference.

In a variation, but not shown, but it is also possible to have two cables (and terminals) per phase and neutral at the incoming to the cutout housing.

The other pin 20 of the pair of pins is also connected directly to a network supply terminal 22b which is the same as the consumer supply terminals 22b. These network supply terminals 22b are used to connect electricity supply cables (not shown) for an incoming electricity supply from a network supplier. In the embodiment described herein a single network supply terminal 22b is provided.

Recesses 29 can be provided for mounting the consumer network terminals 22a in the compartments.

In the fourth compartment 4' the connecting members comprise two connecting plates 26 connected by a bridging contact 27. An intermediate L-shaped connecting plate 53 is also provided which connects to an earth terminal 37 arranged externally of the housing 2. The L-shaped connecting plate 53 and earth terminal 37 are optional depending upon the earthing system used in the particular application Each compartment 4, 4' is provided with mounts 28 which are used to secure the respective connecting members 19, 20, 25, 26 to the housing 2.

Each of the end apertures 8 have a removable cover 31. Each removable cover comprises two, separate identical portions 31 a, 31 b with frusto-conical shaped grommets 54. The grommets 54 provide a seal at the cable entry points The grommets 54 are cut off at a position to suit the diameter of the cable, thereby allowing it to nip' onto the cable insulation and seal when the cable is pushed through the grommets 54. Two grommets 54 are provided at each entry point so as to allow one cable to be connected or disconnected with minimal disturbance to the second cable in the pair (if used).

The three of the compartments 4 for the single phase input lines Li, L2, L3 have a toroidaj current transformer 32 housed between the one 19 of the pair of pins and the consumer supply terminals 22a. The current transformer 32 is arranged so that the Y-shaped member 21, or elongate member 25, if used, runs through the centre of the current transformer 32.

The output (not shown) from the cwTent transformer 32 is fed, by wires (not shown), out through the rear portion 7 of the housing 2 through apertures 33 provided in the side of each of the compartments 4, 4'.

The fourth compartment 4' does not include a current transformer.

The current transformer 32 is dimensioned so that it can fit within the compartment 4, The current transformer 32 can be any suitable current transformer design as known to persons skilled in the art. The core dimensions, the number of turns and the gauge of the wire used for the secondary winding are selected to achieve the required ratios, output power and accuracy as required by the particular application.

When assembled the cut-out housing 2 is a single cut-out unit with four compartments 4, 4'. The three of the compartments 4 for the single-phase lines Li, L2, L3 all have a pair of pins 19,20 extending through the respective pairs of apertures 14, 15 into the respective one of the three cavities 13. The fourth compartment 4' includes the connecting plates 26 connected by a bridging contact 27 and these extend through the single longitudinal slit 18 and into the respective fourth cavity 13'.

Fuse holders 30 can be slotted into the first three cavities 13 so that the distal ends of the pins 19, 20 contact the fuse terminals 50, In this way, current flow pathways are defined which extend from the network supply terminals 22b, through respective pin 20 to the fuse 16 From there, the curi ent flow pathway runs through the fuse along the respective pin 19, along the Y-shaped member 21 to the consumer supply terminals 22a.

In respect of the fourth compartment 4', the current flow path is via the connecting plates 26 and bridging contact 27 instead of through a fuse.

Mounted onto the side of the housing 2, is a meter housing 34, and onto which the electricity meter 17 is hingedly mounted.

The meter housing 34 is secured to the housing 2 by means of screws through the side wall of the rear portion 7 and the meter housing 34. A spacer 35 is provided between the meter housing 34 and the main body 5 of the housing 2. The spacer 35 includes an aperture 44 through which wires from the current transformer 32 and the current flow path can be fed.

The meter housing 34 has a front cover 36 onto which the meter 17 is mounted. An additional meter support bracket 42 can be provided on the front cover 36. The front cover 36 is hingedly connected to the meter housing 34 by means of hinges 45.

A mating pair of brackets 55a, 55b are provide to hold the hinged front cover 36 closed on the meter housing 34. Cooperating holes 56 in the two mating brackets 55a, 55b can be used to provide an anti-tamper seal made of steel wire and a lead seal.

The meter 17 is a conventional meter known to persons skilled in the art. As with conventional meters, the meter 17 can include a display 58.

Within the meter housing 34 there are provided meter voltage supply protection ftises 39, a unit 40 incorporating current transformer shorting links 43, secondary meter voltage supply protection frises 57 and terminals for connections to the meter. The meter voltage supply protection fuses 39 are supported within the meter housing 34 by support brackets 38. The unit 40 is supported by support brackets 41 attached to the inside of the front cover 36.

By providing shortage links between the output circuitry from the current transformer, the meter can be removed without disrupting the power supply. The voltage supply can be isolated by removing the fuses 39.

An example of a suitable meter 17 is the Type A1700 as manufactured by Elster Metering Ltd. The output from each current transformer 32 is connected to a respective current transformer shorting link 56 and from there to the meter 17. A voltage output is also taken from each of the phase lines Ll, L2, L3 and the neutral line N to a respective meter voltage supply fuses 39 and secondary meter voltage supply fuses 57 to the meter 17. The wire connections coupling the voltage output to the meter 17 are also taken out through the apertures 33 through the wires connecting the output from the current transfonner 23 are fed.

The meter 17 is then able to measure electricity supply consumption in the usual way.

In use, the single phase cables for the network supply are introduced into the first three compartments 4, one phase line Li, L2, L3 to one of the compartments 4 via the apertures 8. The cables are connected to the lower terminal 22c. The neutral line is connected to the fourth compartment 4' in the same way.

Similarly, the consumer supply cables are connected to respective consumer supply terminals 22a. The consumer supply cables can be single cables or a pair of parallel cables as described above.

Current is able to flow through the cut-out assembly 1 along the current flow paths described above.

In the embodiment described herein, the cut-out assembly has a depth of around 270mm and total width of 623mm and a total height of 475mm. Each compartment 4, 4' is substantially similar in width.

Modifications are possible withrn the scope of the present invention In particular, it should be understood that each compartment 4, 4' and the arrangement of connecting members 19, 20, 21,25 can be varied. Any, or all, can be provided with consumer output terminals 22a can be provided singly, or in pairs. For example, each compartment can have Y-shaped connectors 2t, or the compartment 4, 4' can have all single elongate connectors 25, or combinations thereof can be provided.

The connectors can be configured to accommodate different cables or customer preference.

Additionally, the number of cable terminations could be increased to accommodate three or more cables per phase.

Claims

CLAIMS1. A cut-out assembly for use in an electricity distribution network, the assembly comprising a cut-out housing and an electricity meter mounted on the cut-out housing, the cut-out assembly including a plurality of input terminals for connecting to single phase inputs of an electricity supply, a plurality of output terminals for connecting to cables of a consumer electricity network, a plurality of connecting members defining a current flow path between each one of the input tenninals and a respective one of the output terminals, and a plurality of current transformers provided in at least one of the defined current flow paths to provide a transformed current to the electricity meter in response to current flow in the at least one of the defined current flow paths, with only one current transformer in any one current flow path, wherein the input terminals, output terminals, coimecting members and the current transformer are provided within the cut-out housing.
2. A cut-out assembly according to claim 1, including a plurality of fuses provided in at least one of the defined current flow paths.
3. A cut-out assembly according to claim 2, wherein the current transformer is provided in the at least one defined current flow path between the respective fuse in the defined current flow path and the respective output terminal.
4. A cut-out assembly according to claim 2, wherein the the current transformer may be provided in the at least one defined current flow path between the respective fuse in the defined current flow path and the respective input terminal.
5. A cut out assembly according to any of claims 1 to 4, wherein the current transformer is a toroidal current transformer arranged around one of the connecting members of the respective defined current flow path.
6. A cut out assembly according to any preceding claim, wherein the connecting members include a pair of pins, one pair per current flow path, and configured for connection to respective terminals of the fuse,
7. A cut out assembly according to claim 6, wherein the connecting members include a further connector, connected between one pain of each pair of pins and a respective output terminal.
8. A cut out assembly according to claim 7, wherein the further connector is a shaped connector.
9. A cut out assembly according to claim 7, wherein the further connector is an elongate connector.
10. A cut out assembly according to any of claims 6 to 9, wherein the connecting members further includes a bridging connector connected between a two connecting plates.
11. A cut out assembly according to any preceding claim wherein the cut out housing includes a plurality of compartments, each compartment housing a selection of the plurality of connecting members such that there is defined a single current flow path between each one of the input terminals and a respective one of the output terminals in each compartment.
12. A cut out assembly according to claim 11 wherein one or more of the compartments includes one of the current transformers.
13, A cut out assembly according to any preceding claim, wherein the meter is mounted on a meter housing, the meter housing being att ached to the cut-out housing and housing circuitry for coupling the output from the current transformer and a voltage from the current flow path to the meter.
14. A cut-out assembly according to claim 13, wherein the circuitry includes current transformer shorting links configured to bridge the connections between the current transformer and the meter so as to short circuit the transformer.