Feature Panel Building


conomic times are tough and companies, particularly those in the manufacturing and produc- tion sectors, are under constant pressure to be more efficient. Processes and manpower require- ments within these environments can be examined in order to squeeze out costs. However, there is one area intrinsic to production capability that offers a simple and effective route to expenditure sav- ings and speedier application - low volt- age motor control centres (MCCs).


MCCs


The basis of any industrial application is formed by MCCs as they are used to centralise the distribution of power and control to the electric motors utilised in manufacturing and produc- tion - from car production plants to the process industries.


Usually an assembly of one or more enclosed sections, they have a common power bus and contain motor control units. A motor control centre can include variable frequency drives, pro- grammable controllers and are used for low voltage three-phase alternating cur- rent motors from 230V to 600V. An MCC is a key element in power- ing and controlling motor architecture, so the associated time and cost consid- erations of any MCC development and installation are important factors when looking at the overall cost and effectiveness of production processes. There are different types of MCC panels depending on the complexity of the systems they are required to control. The simplest is an ‘open wardrobe’ type panel (Forms 1 and 2), while Forms 3 and 4 refer to compart- mentalised panels where different aspects of a process have to be physically separated to allow individual control and isolation. Traditionally, the long established Form 4 approach has been the basis for the design and build of the MCC. The reason for this is due to the principle of ‘separation’ which is overseen by British Standard EN 60439-1. It states that Form 4 assembly should, for


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Form a queue for significant savings E


With organisations constantly looking for ways to reduce costs and increase efficiency, Mark Harrison, from Siemens Industry, champions the role that Form 2 motor control centre design can play in achieving this


instance, provide ‘separation of bus- bars from the functional units and sep- aration of all functional units from one another, including the terminals for external conductors which are an inte- gral part of the functional unit’.


Broadening horizons


As a result the development of many historic MCC applications has been underpinned by this long held approach. However, it could be argued that the time has now come for panel builders and end users alike to more proactively embrace the commercial and industrial advantages inherent in Form 2 design and assembly. Form 2 seeks separation of busbars from the functional units, but terminals for external conductors do not need to be separated from the busbar itself. Adopting Form 2 could lead the way to substantial cost and space savings for end users, as well as offer- ing a far more flexible solution to enable panel builders to deliver MCC panels to market in less time, as well as more competitively.


While Form 4 is still heavily specified in many industries, it could be said that the very separation provided by a Form 4 style enclosure is actually provided by the modern design of the internal devices themselves. This was not the case when the first MCCs appeared in the 1950s on car production plants. While this separation point can be debated, nonetheless, it is worthy of serious consideration and Form 4 could, in the current marketplace, be an unnecessarily expensive method of MCC design.


Above: Mark Harrison of


Siemens Industry Summary


Below: it could be argued that the time has now come for panel builders and end users alike to more proactively embrace the commercial and industrial advantages inherent in Form 2 design and assembly


The increasing use of Form 2 is an important development for new facto- ries, as well as those undergoing retro- fits. Form 2 provides access to smaller sized panels with direct cost savings in terms of reduced cabling, installa- tion and labour. Smaller panels can also contribute directly to lower civil engineering costs, with less space required to house the units, meaning overall building design can take this important (and costly) factor into account at planning stages.


From an operational viewpoint, the MCC panel components themselves are vastly improved via the Form 2 approach. With increased integration possible with system control and inno- vative diagnostics providing a route to fast problem solving and fault finding, the operational efficiencies associated with, for example, preventative mainte- nance strategies are clear. With easier to swap components reducing plant down-time, plant production effective- ness can also be impacted positively. For the modern production business looking to make inroads into spiralling costs without reducing their operational efficiencies, and MCC panel builders wanting to get to market more quickly, adopting the methodology of Form 2 MCC panel design makes perfect sense.


Siemens www.industry.siemens.co.uk T: 0161 446 6400


Each year, manufacturers invest huge amounts in research and devel- opment into low voltage control gear to generate innovative methods that can allow their products to gain a competitive market advantage and save the electrical panel builder money. As a result, modern control gear now allows the provision of many individual motor starters in an increasingly smaller amount of space - thanks to reduced physical sizes, modular concepts and reduced wiring requirements.


Such innovation allows for reduced MCC cabinet size and the associated benefits it delivers are in essence lost if Form 4 assembly remains, as in such cases each individual starter requires its own compartment.


Form 2 also offers a greener solution - a tangible by-product of manufactur- ing smaller cabinets is the reduced use of raw material sources in the form of steelwork and even less transportation - both aspects contributing to a more sustainable future.


Enter 221 DECEMBER/JANUARY 2013 Electrical Engineering


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