Nominal Voltage in an Electrical System

Definition and Importance of Rated Voltage in an Electrical System

You have certainly heard of nominal voltage of an electrical system. In this article, we will try to clarify what exactly it is and how the nominal voltage is calculated.

What is Nominal Voltage?

The nominal voltage, also known as nominal current, represents the electrical value - i.e. the voltage - that is used during the design phase of an electrical system. It is crucial to know that the nominal voltage can differ significantly from the actual voltage felt in daily use.

The Rated Voltage in Civil Homes

In the context of civil homes, the nominal voltage is normally established around 220/230 V. However, it is normal that it may undergo oscillations which vary its value, sometimes raising or lowering it. This phenomenon is particularly important to monitor since there is a legal limit to such fluctuations. As long as these remain within 230 V, we can rest assured that household appliances and other electronic devices will not suffer damage.

Importance of Maintaining Voltage Limits

It is important to underline the importance of keeping voltage fluctuations within the limits established by law. This guarantees the safety of the electrical system and the longevity of the devices that use it. Understanding and controlling the nominal voltage and its variations is therefore essential for the protection of domestic electronic systems and devices.

Calculation of the Nominal Voltage

• Establish the design voltage value of the system.
• Observe the technical specifications of the devices that will be connected to the system.
• Consider the possible variations and oscillations allowed to ensure safety.

Through these steps, you can get a clear idea of how the rated voltage of an electrical system is determined and how to control its variations to prevent possible damage.

Differences between the Types of Electrical Systems

Systems Depending on the Nominal Voltage

The differentiation of electrical systems can be made based on their nominal voltage. This parameter allows us to classify the systems into different categories:

• Very low voltage systems: characterized by a nominal voltage lower than 50 V.
• Low voltage systems: these systems have a voltage between 50 and 1000 V, representing the most common type in homes.
• Medium voltage systems: the nominal voltage in these cases is between 1000 and 30000 V.
• High voltage systems: have a voltage greater than 30,000 V.

Regulation of Domestic Installations

As regards domestic systems, which are more relevant for most people, it is essential to know the CE-I 64-8 regulation. This regulates all electrical systems operating below 1000 V, ensuring safety and reliability standards.

Voltage Oscillations

We have previously mentioned how oscillations in the nominal voltage must be contained within certain limits, so as not to compromise the functioning of electrical devices. The CE-I 64-8 regulation establishes that the real voltage can oscillate within 4%, but without ever exceeding 10%. This interval ensures the correct functioning of electrical devices without causing damage.

Calculation of Nominal Voltage: Step by Step Guide

Understanding the calculation of nominal voltage is essential in the world of electronics and electrical engineering. But how do we proceed? The fundamental distinction to make is between a single-phase system and a three-phase system, since the calculation differs significantly between these two types.

Single-phase system

In the case of a single-phase system, the calculation procedure is more direct. The nominal voltage, in this scenario, is simply the potential difference between the phase and the neutral. This makes the calculation process relatively simple and immediate.

Three-phase system

For three-phase systems, however, the situation becomes more complicated since there are two types of nominal voltage. On the one hand we have the line voltage, calculated between two of the available phases. On the other hand, the phase voltage, which is obtained from the potential difference between a phase and the neutral. This distinction is crucial and necessary for a correct choice of the components that will make up the system.

Final Considerations

When designing or working on a system, knowing and understanding how to calculate the nominal voltage is essential. This is not only a matter of compliance with current regulations, but also to guarantee the safety and efficiency of the system itself. Making sure you correctly specify the type of nominal voltage based on the system in question is therefore a critical step in making the right choice regarding the various components.

Practical Summary

• Single-phase system: Nominal voltage calculated as the potential difference between phase and neutral.
• Three-phase system: Double nominal voltage – line voltage (between 2 phases) and phase voltage (between phase and neutral).

Understanding the nominal voltage and its calculation is therefore the first critical step for the installation or maintenance of an efficient and compliant electrical system.