Для чего разделяют PEN проводник на PE и N? Почему после разделения нельзя соединять PE и N?

Summary

The video from Malk Engineering explains how an electrical panel works, focusing on the separation of the PEN conductor into neutral (N) and grounding (PE). It covers the importance of not reconnecting these after separation, discusses different grounding systems (TN-CS and TT), and emphasizes the use of residual current devices (RCD) for safety. The video also explains the role of grounding in enhancing the safety and stability of electrical systems. For those interested in learning more, the video promotes a KNX24 course on electrical engineering and grounding installation.

Takeaways

• 🔧 The PEN conductor is split into neutral (N) and grounding (PE) to enhance safety, preventing the mixing of protective and operational conductors.
• ⚡ In a TN-C system, the neutral and protective grounding are combined into one PEN conductor. This is later split into PE and N conductors in the electrical distribution board (VRU).
• 🛡️ It's essential not to reconnect PE and N after separation because it compromises the effectiveness of grounding, risking potential faults.
• 🌍 Grounding ensures safety by reducing electric shock risks, lowering fire hazards, and protecting equipment.
• 🔌 The TN-C-S system is the most common grounding system in Russia, where PE and N are separated but linked to a grounded point.
• ⚙️ In the TT system, without the direct connection between neutral and ground, protective devices like differential switches (RCDs) are required to ensure safety.
• 🌀 An RCD detects current imbalances between the phase and neutral conductors, disconnecting the circuit when necessary, but does not protect against short circuits or overloads.
• 🚨 If the PEN conductor breaks in a TN-C system, dangerous conditions arise, making proper grounding and separation crucial for protection.
• 🔩 A well-designed grounding system can also help stabilize voltage levels, contributing to overall electrical system stability.
• 🎓 The video promotes an electrical course focused on proper grounding and electrical safety, offering a discount for viewers using a specific promo code.

Q & A

What is the role of the PEN conductor in an electrical system?

The PEN conductor combines the functions of both the protective earth (PE) and the neutral (N) conductors. It is used to carry return current and provide safety by connecting to the grounding system. In TN-C systems, the PEN conductor serves both roles until it is separated into PE and N.

Why is it important to separate the PE and N conductors in an electrical panel?

Separating the PE and N conductors is crucial for safety. The PE provides a dedicated path for fault currents, reducing the risk of electrical shock and equipment damage, while the N is used for returning current to the source. After separation, it is important to keep them isolated to prevent parallel paths that could create dangerous conditions.

What happens if the PE and N conductors are reconnected after separation?

Reconnecting the PE and N conductors after separation creates parallel paths for current to flow, which can lead to safety hazards. Current can flow through unintended paths, such as metal enclosures, creating shock risks. It also compromises the effectiveness of protective devices like circuit breakers.

What are the key differences between the TN-C and TT grounding systems?

In the TN-C system, the PEN conductor serves both protective and neutral functions, while in the TT system, the neutral and protective earth are completely separate. The TT system relies on separate grounding electrodes, so fault currents flow through the ground rather than the PEN conductor.

Why is a residual current device (RCD) needed in TT systems?

In TT systems, fault currents can flow through the ground, which may not provide a low enough resistance to trigger a regular circuit breaker. An RCD detects differences between the current in the phase and neutral conductors and disconnects the circuit if there is a fault, enhancing safety.

How does the RCD (residual current device) operate in the event of a fault?

The RCD operates by continuously monitoring the current balance between the phase and neutral conductors. If it detects a difference, which suggests a leakage current (e.g., through a person or faulty equipment), it quickly disconnects the circuit to prevent harm.

What are the consequences if the neutral conductor becomes disconnected in a TN-C system?

If the neutral conductor is disconnected in a TN-C system, current may flow through the grounding system, including exposed metal parts, creating a high risk of electric shock. This can also lead to improper operation of the system and increased voltage on the equipment.

Why is grounding important in electrical systems?

Grounding provides a safe path for fault currents, protecting people and equipment from electrical shocks and fires. It stabilizes the voltage levels in the system and ensures that the electrical system operates safely by dissipating excess energy into the earth.

What is the purpose of using a differential circuit breaker in conjunction with grounding systems?

A differential circuit breaker, or RCD, provides an additional layer of protection by detecting leakage currents that may not trigger a standard circuit breaker. It helps prevent electric shock by disconnecting the circuit when it senses an imbalance, which could indicate current leakage through the body or equipment.

What would happen in a TN-C system if the PEN conductor is disconnected?

If the PEN conductor is disconnected in a TN-C system, all protective and neutral functions are lost. This can cause dangerous situations where metal parts of equipment become live, leading to electric shocks and system failures.