JO/le
Applicant: ABB Technology Ltd
A method for manufacturing a plurality of switchboards
TECHNICAL FIELD OF THE INVENTION AND PRIOR ART
The present invention concerns a method for manufacturing a plurality of low- or medium-voltage switchboards having different dimensions, which are particularly but not exclusively intended for compact secondary substations. The present invention also relates to a low- or medium-voltage switchboard manufactured by such a method.
Low- or medium-voltage switchboards are widely used in technical fields concerning the generation, distribution and use of electrical energy. They can be used as main and sub- distribution boards for energy, motor current supply for Motor Control Centres (MCCs) or electronic cabinets for open and closed-loop control purposes. They are used in power plants, oil refineries, on sea-going vessels, production facilities and buildings.
Low- or medium-voltage switchboards are usually implemented as floor-standing cubicles. Frames are constructed for the various cubicle types and the cubicles are then subdivided into different compartments/functional areas such as an equipment compartment that holds the equipment modules, a busbar compartment that accommodates busbars and distribution bars that interconnect the busbars and the modules, and a cable compartment that contains incoming and outgoing cables and the wiring required for connecting the modules. The cubicles' panels are usually made of surface-treated and/or painted steel plate.
As well as containing busbars a low voltage switchboard also comprises neutral (N) and protective neutral bars (PEN). The neutral conductor (N) is insulated while the protective conductor (PE) or common neutral- and protective conductor (PEN) is mounted in contact with the cubicle construction.
The width, height, depth, structural design and interior arrangement of a low- or medium-voltage switchboard are very flexible due to the switchboard's framework construction. It is possible to manufacture low- or medium-voltage switchboards of any desired size and type ranging from low- or medium-voltage switchboards including only a few components and covering only the basic requirement, which is the supply of power to low- or medium-voltage switchboards providing sophisticated and space-demanding additional functions. Not only are low- or medium-voltage switchboards available in different dimensions but there are also several different busbar systems and a number of different frameworks, different busbar profiles and different busbar fasteners.
This adds up to a large number of variables making it very difficult to manufacture different types of low- or medium-voltage switchboards on an industrial scale. Low- or medium-voltage switchboards are therefore usually custom-built and fitted with the components required for a particular application. Such a one-off manufacturing process is however time-consuming and not cost effective and it is necessary to have a different assembly line for each low- or medium-voltage switchboard in a manufacturing plant.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an improved method for manufacturing a plurality of low- or medium-voltage switchboards of different dimensions (i.e. different widths, heights or depths) in a cost-effective and efficient way.
This object is fulfilled using a method having the features of claim 1 , namely a method which comprises:
a number of steps of a first production line A comprising:
A1 ) manufacturing a first mounting plate for busbars,
A2) providing said first mounting plate with means to mount a number of different busbar holders thereon, A3) providing said first mounting plate with a pattern of fixture holes to allow busbars with a predetermined number of different profiles to be mounted thereon, A4) mounting one or more busbars on said first mounting plate,
a number of steps of a second production line B carried out in parallel with said steps of the first production line and com¬ prising:
B1 ) manufacturing a second mounting plate for PEN-bars, B2) providing said second mounting plate with means for mounting a PEN-bar that is earthed or insulated thereon and/or for mounting a PE-bar and an N-bar, each earthed and insulated, thereon,
B3) mounting one or more PEN-bars and/or PE-bars and N- bars on said second mounting plate,
whereupon said first and second mounting plates are mounted on a support in common, such as a framework.
This method with steps in two parallel production lines for preparing said first and second mounting plates makes it possible to easily manufacture a plurality of switchboards of different dimensions. By the feature of providing the first mounting plate with a pattern of fixture holes to allow a predeter- mined number of busbar profiles to be mounted thereon, this mounting plate will have the capability of being utilized in any type of low- or medium-voltage switchboard having the same dimension as the mounting plate.
The first and second mounting plates not only simplify the fabri¬ cation and assembly process but make it simple to upgrade or modify an existing product by adding additional functions or extra features for example.
According to an embodiment of the invention the method comprises the step of manufacturing the first and second mounting plates in a predetermined number of different dimensions, such as a number of different widths, so as to suit a plurality of different applications, such as to suit all compact secondary substations in which the mounting plates will be used.
Either one, or preferably two basic construction elements for the power supply and the DIN-rail system are therefore produced in a plurality of different dimension variants to cover the entire range of low- or medium-voltage switchboards that are required. By mass-producing these common components lead-times and production costs are reduced. Furthermore, the total number of different components is reduced, thus reducing stock and capital invested in the stock. The velocity of circulation of stock also increases, resulting in better economic figures overall. Using a low- or medium-voltage switchboard manufactured using the method according to the present invention in a compact secondary substation reduces the lead-time for the entire assembly.
According to a further embodiment of the invention the method comprises the step of providing the second mounting plate for
PE/N-bars with an integrated cable support clamp. The cable support clamp is usually an individual component that is mounted separately in the compact secondary substation.
Integrating this component with the second mounting plate reduces the assembly time and consequently assembly costs.
According to another embodiment of the invention the method comprises a step in a third production line C carried out in pa¬ rallel with said steps of said first and second production line of manufacturing a framework for the low- or medium-voltage switchboard having the required dimensions for mounting said first and second mounting plates thereon. By this third production line in parallel with said first and second production lines low- or medium-voltage switchboards corresponding to an intermediate category of known switchboards may easily be produced with a high flexibility.
According to another embodiment of the invention the method comprises the steps in a fourth production line carried out in pa¬ rallel with said steps of said first, second and third production lines of mounting at least one DIN-rail and mounting DIN-rail components thereon, and then mounting said DIN-rail with said components on said framework. This involves a flexible and effi¬ cient way of manufacturing low- or medium-voltage switchboards corresponding to an upper category of such switchboards already known.
According to another embodiment of the invention a DIN-rail with a length proportional to a dimension of the low- or medium- voltage switchboard is mounted on said framework. This allows more functions to be built into a wider range of variants of switchboards, and a DIN-rail with a length being substantially equal to a dimension of the low- or medium-voltage switchboard is preferably mounted on said framework. This provides for a higher flexibility in providing the switchboard with different further functions.
According to another embodiment of the invention the method comprises the step of mounting an incoming switchboard supply breaker on a said carrier in the form of a framework. The compartment for such an incoming switchboard supply breaker may be centrally placed on said framework, for example above the first mounting plate for busbars.
The invention also concerns a low- or medium-voltage switch¬ board produced by using a method according to any of the embo¬ diments of the invention described above as well as a compact secondary sub-station which contains a low- or medium-voltage switchboard produced using the method according to any of the embodiments of the invention.
Further advantages as well as advantageous features of the in- vention appear from the following description and the other de¬ pendent claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 shows a first and a second mounting plate according to an embodiment of the invention,
Fig. 2 represents part of a low voltage switchboard comprising a first and a second mounting plate according to an embodiment of the invention, and
Fig. 3 is a flow chart showing a method according to a preferred embodiment of the invention.
It should be noted that the figures are not drawn to scale and that the size of certain features has been exaggerated for the sake of clarity.
The following description and drawings are not intended to limit the present invention to the embodiment disclosed. The embodiment disclosed merely exemplifies the principles of the present invention.
DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION
Figure 1 shows a first mounting plate 1 for busbars and a second mounting plate 2 for PE/N-bars intended for a low voltage switchboard for use in a compact secondary substation.
The first mounting plate 1 has a width, W1, and three busbar holders 3 have been mounted thereon using the fixture holes 4 that have been pre-drilled in the mounting plate 1. The busbar holders are horizontal in the example shown but they could have any orientation.
The second mounting plate 2 also has a width of W1. It has been equipped with means 5 to mount one PEN-bar that is earthed or insulated thereon. It also comprises a pattern of pre- drilled fixture holes 4.
Figure 2 shows part of a low- or medium-voltage switchboard comprising mounting plates 1 and 2. The mounting plates 1 ,2, are mounted in a frame 6 having the required height, h, and depth, of, for the compact secondary substation in which the low- or medium-voltage switchboard will be used. The frame 6 is provided with one or more DIN-rails 7 having a length W1 on which additional functions may be added. The switchboard in figure 2 constitutes part of a floor-standing unit, however the present invention is equally applicable to wall-mounted units.
Figure 3 is a flow chart outlining the steps of a method of assembling a low-voltage switchboard of width W1. Alternatively the method could be applied to construct a switchboard of a certain height or depth. The method for assembling any type of low- or medium-voltage switchboard having a width W1, W2, W3, W4 or W5 is carried out in a streamlined way on four assem¬ bly or production lines A, B, C and D. One-off production me- thods according to the prior art would require one assembly line for each switchboard.
A frame of the required height and depth is constructed on assembly line C. A first mounting plate 1 having the required width, W1 , is produced on assembly line A. The mounting plate 1 is provided with mounting means so that it may be mounted in any low- or medium-voltage switchboard of width W1. It is also provided with fixture holes so that any of the busbars used in any of the different types of low- or medium-voltage switchboards may be mounted thereon.
A second mounting plate 2 having the required width, W1 , is produced on assembly line B. The mounting plate 2 is provided with mounting means so that it may be mounted in any low- or medium-voltage switchboard of width W1. It is also provided with fixture holes so that any of the PE/N-bars necessary for any of the different types of low- or medium-voltage switchboards may be mounted thereon.
On assembly line D one or more DIN-rails are mounted on the framework or on one or both of the mounting plates and the necessary switchboard components are mounted thereon. A low- voltage switchboard is then assembled by mounting the mounting plates 1 and 2, DIN-rails and switchboard components on the frame 6 and securing steel plates to the frames for example.
The four parallel assembly lines shown A, B, C, D, may be used to manufacture any number of low- or medium-voltage switchboards of widths W1, W2 W3, W4 or W5 efficiently and cost-effectively. The widths may for example be 70cm, 80cm, 100cm, 1 10cm and 120cm respectively.
The invention is of course not in any way restricted to the embodiments thereof described above, but many possibilities to modifications thereof would be apparent to a man with ordinary skill in the art without departing from the basic idea of the invention as defined in the appended claims.
For example the mounting plates do not necessarily have to be of the shape and structure shown in the figures but may be constructed in any shape of form that can be mounted in a low- or medium-voltage switchboard and support the switchboard's components.