Aterramento - A melhor explicação do Youtube passo a passo

Summary

This video script provides a comprehensive explanation of electrical grounding (aterramento) systems, emphasizing the importance of protecting both people and equipment from electrical hazards. It covers key grounding concepts, including the difference between protection and functional grounding, the role of grounding in electrical installations, and the standards for grounding resistance (NBR-5410). The script also details various grounding schemes (TN-S, TN-C, TT, IT) and the necessary specifications for protection conductors, ensuring electrical safety in diverse environments.

Takeaways

• 😀 The purpose of grounding in an electrical installation is to direct potential leakage currents to the earth, thereby protecting both people and equipment.
• 😀 Grounding provides a parallel path with lower resistance to the earth, and the current will flow through the path with the least resistance.
• 😀 The lower the grounding resistance, the better the grounding system will be, with a maximum value of 3 ohms according to NBR-5410.
• 😀 A device called a 'terrometer' is used to measure the grounding resistance.
• 😀 Grounding can serve functional purposes as well, such as for signal transmission, in addition to protective grounding.
• 😀 Protective grounding (PE) is essential for preventing electric shocks caused by indirect contact with energized masses.
• 😀 The grounding of the neutral in a low-voltage system does not aim at protection but provides a return path for currents circulating through the neutral.
• 😀 The protection is only effective when the equipment has a dedicated protection conductor that is properly grounded.
• 😀 The minimum size of protection conductors should follow NBR-5410 recommendations, with specific sizes based on the phase conductor's section.
• 😀 There are different grounding schemes such as TN-S, TN-C-S, TN-C, TT, and IT, each with its own method of neutral and protection conductor arrangement.
• 😀 In an IT system, the neutral is not grounded, and only the protection grounding is implemented to ensure safety.

Q & A

What is the purpose of grounding an installation?

The purpose of grounding is to direct potential leakage currents to the ground, protecting people and preserving equipment. It provides a parallel path with lower resistance for electrical current to flow safely to the earth.

Why is the value of grounding resistance important?

The lower the grounding resistance, the better the grounding system. A lower resistance ensures that the electrical current flows through the grounding path instead of other paths, minimizing the risk of electrical hazards.

What is the maximum allowable grounding resistance according to NBR-5410?

According to NBR-5410, the maximum allowable grounding resistance is 3 ohms.

What device is used to measure grounding resistance?

The device used to measure grounding resistance is called a 'terrometer'.

What is the difference between protective and functional grounding?

Protective grounding is intended to prevent electric shocks by directing leakage current safely to the ground. Functional grounding, on the other hand, is for purposes such as signal transmission and does not necessarily serve a protective role.

What is the purpose of grounding the neutral in low-voltage systems?

The neutral is grounded in low-voltage systems to provide a return path for any circulating current, ensuring the system's stability. This is important even if the system is balanced or unbalanced due to factors like increased demand or illegal connections.

What is the role of protective grounding (PE) in preventing electric shock?

Protective grounding prevents electric shock by ensuring that any metallic part that should not be energized (but is due to a fault) is safely grounded. This path provides a low-resistance route to the earth, reducing the risk of electrocution.

What is the minimum required size for protective grounding conductors according to NBR-5410?

According to NBR-5410, the minimum size of protective grounding conductors depends on the size of the phase conductors. For circuits with phase conductors up to 16 mm², the protective conductor must match this size. For conductors between 16 and 35 mm², the protective conductor should be 16 mm². For larger phase conductors, the protective conductor must be half the size of the phase conductor.

What color should protective conductors be according to NBR-5410?

Protective conductors should be either green or a combination of green and yellow, according to NBR-5410.

What is the function of the protective conductor when there is no leakage current?

In a properly functioning circuit without leakage current, no current should flow through the protective conductor. However, if leakage current occurs, it will flow through this conductor to the ground.

What are the different types of grounding systems used in low-voltage installations?

The different grounding systems include: TN-S (neutral and protection conductors are separate), TN-C-S (neutral and protection functions combined in one conductor in part of the circuit), TN-C (neutral and protection combined in one conductor throughout the installation), TT (neutral grounding is separate from protection grounding), and IT (the neutral is not grounded, only protection grounding is provided).