The design of an electrical system is a delicate operation from every point of view.
Mainly it can be divided into three distinct phases, each of which must necessarily be subject to precise rules that guarantee safety during the execution of the works and during the commissioning of the plant.
They correspond to:
– a first phase in which the designers study the design criteria to be taken into consideration before the construction and installation of the system, with particular reference to the standards not to be neglected before the actual design;
– a second phase of actual design, in which each single electrical component will be designed according to the type of system to be built;
– a third phase in which the final design of the system will take place, with the various components that will find space inside the plant itself.
First phase: the study of the project criteria
The designers are required to study in detail the criteria and the laws to be respected so that the planning is done according to the law.
First of all, the various components that characterize the system must be taken into account:
- the supply circuits (both of the appliances directly used by the users, and of the plug sockets)
- protection circuits, fundamental elements to guarantee the absolute safety of the single users in the building where the works will be carried out.
The study phase must take into account not only the environmental safety, but also the needs of the customer (therefore the flexibility of the system), all in compliance with the directives of the CEI standards.
The design must also take into account the electrical load used and the size of the building (in particular the walking surface of the individual areas of intervention), subdividing the rooms according to the performance that the system components must meet.
The division includes three levels:
- the basic level (sockets and light points placed in minimum number in the intervention areas, as the number of circuits will be reduced)
- standard level (greater components than the basic level)
- home automation level (management of a higher number of electrical functions by the system, with reference also to energy saving).
Once the individual design levels have been established for the various areas of the building, always based on the general criteria set by the safety design standards, the design phase of the components that will constitute the plant will take place.
Second phase: the design of the system components
Several factors must be taken into account when designing the individual components of the electrical system.
In the case of the design of a residential building, which will have to distribute low-voltage electricity, components are made to be used in single-phase or three-phase circuits.
In single-phase circuits, the voltage is fixed at 230 volts, while in the three-phase voltage is set at 400 volts, and in both cases the neutral and a grounding cable will be present.
In the next phase, the realization of the circuits is started according to the number and type of users, while studying the best positioning for each component.
Also in this case reference must be made to the CEI standards, in particular to the regulations concerning the use current and to the sizing of the cables, of the upright, of the neutral conductor and of protection.
After having established the amount of power that the system must deliver, the electrical panel must be designed, which will connect to the switches, lights and all the sockets and equipment inside the system. Also essential is the preparation and commissioning of life-saving switches, which are essential for a higher guarantee of safety inside the home.
Third phase: the actual planning of the plant
Finally we come to the third phase, the actual design of the electrical system: in this juncture an architectural drawing is created containing the plants related to the building in which the system will be installed.
Subsequently the system is modelled with the components that will be placed within the individual areas of intervention.
At the end of the realization of the project, the whole plant must be verified through a calculation phase that will take into account, for example, the analysis of possible voltage drops, so as to be certain of the real operation of the various components of the plant.
The aim of the design must be to create an electrical installation as efficient as possible, both from the point of view of reducing energy waste, from that of a minor use of material and last but not least, from the realization of the circuit in the as little time as possible.
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