CEMIG l ND 2.9 l Aula 04 l Instalações Básicas de Redes Compactas

Name: CEMIG l ND 2.9 l Aula 04 l Instalações Básicas de Redes Compactas
Uploaded: 2022-05-29T12:00:11.000Z
Duration: 2 h 50 min 18 s

Introduction to Compact Network Installations

Overview of the Video Series

The video is part of Tom's channel focused on electricity and safety, specifically presenting lesson MD 2.9.

Tom explains his organizational approach in recording lessons, noting that he skipped MD 2.7 for better coherence in understanding the norms.

Importance of Understanding

Emphasizes that the key to learning is understanding rather than strictly following a sequence; flexibility in studying different modules is encouraged.

Invites viewers to share their experiences with the channel through short videos, highlighting community engagement.

Network Structure for Derivations

Question 23: Structure Without Fuse Switches

Introduces question number 23 regarding network structure needed for two derivations without fuse switches.

Describes a specific aerial view of the CR23 C3 structure used for this purpose, showcasing its design and functionality.

Explanation of Structures

Details about structure configurations are provided, including how they accommodate multiple connections (two above and one below).

Clarifies that structure three (C3) serves as a compact network with spacers, essential for effective connectivity.

Derivations with Fuse Switches

Question 24: Required Structures

Moves on to question number 24 which asks about structures suitable for derivations using fuse switches.

Lists specific structures (C2, CM3, etc.) necessary for making these types of connections while referencing page details from instructional material.

Visual Representation

Highlights visual aids included in the presentation to enhance understanding of each structure's application.

Discusses structural similarities between conventional and compact designs while emphasizing their functional differences.

Detailed Analysis of Structures

Conventional vs. Compact Structures

Explains how conventional structures integrate into modern compact systems, particularly focusing on fuse switch placements.

Transitional Structures in Electrical Networks

Understanding Conventional to Protected Structure Transition

The discussion begins with the concept of transitioning from a conventional structure to a protected one, referred to as "transição de rei," highlighting the importance of structural changes.

The speaker describes specific components like isolators and cables, emphasizing their roles in maintaining structural integrity during this transition.

A detailed explanation is provided about the function of pin insulators and how they secure conductors, ensuring stability within the network's framework.

The necessity of lightning rods (para-raios) in transmission networks is reiterated, linking back to previous lessons on protective measures for electrical structures.

The current lesson builds upon earlier video lectures, specifically referencing norms that govern these transitions and reinforcing the need for protective structures.

Structural Analysis and Equipment Installation Guidelines

An analysis of various network structures is presented, focusing on configurations such as M1 and CM3, which are essential for understanding different setups in electrical networks.

The importance of adhering to safety standards when installing equipment is emphasized; certain structures should not have derivations or installations due to their design limitations.

Clarification on prohibited actions within compact network structures is provided; these cannot support additional weight or installations without compromising safety.

Visual aids are used to illustrate structural characteristics, including L-shaped arms that stabilize spacers while preventing undue stress on the system.

A distinction between similar structures viewed from different angles helps clarify their functionalities and applications within electrical networks.

Specific Structural Components and Their Functions

Discussion shifts towards J-support arms used for elevating networks above residential areas; these must also comply with installation regulations regarding derivations.

Emphasis is placed on avoiding installations near homes due to regulatory constraints; this ensures compliance with safety standards outlined in relevant guidelines.

Handling Deflection Angles in Network Structures

When deflection angles exceed 30 degrees horizontally, specific measures must be taken—namely installing transition shackles at strategic points along support arms.

Detailed instructions are given regarding shackle placement; this adjustment allows for better mobility and stability under increased tension conditions.

Installation Standards for Isolators

Clear guidelines are provided regarding the distance required for installing polymeric isolators within messenger systems—specifically noted as 2 cm three (cm³).

Installation and Safety of Electrical Components

Overview of Installation Components

The speaker discusses the setup involving a key, suspension insulators, and a structure with two M3 components.

Emphasizes the importance of maintaining a distance of 500mm (5 meters total) from the crossbeam to ensure stability under weight.

Mentions that the messenger wire must be isolated to prevent electrical disturbances in case of defects or operational errors.

Importance of Isolation

Highlights that isolation is crucial to avoid energy transfer that could disrupt other structures within the circuit.

Notes specific distances for installation: 200mm between certain components and 70cm from Salvador to Central, reinforcing safety measures.

Installation Guidelines for Lightning Protection

Discusses where lightning rods should be installed on normally open switches, emphasizing their placement on both sides.

Clarifies that normally open switches require lightning rods on both ends due to their design and function.

Functionality of Switch Types

Describes a knife switch as non-fusible, primarily used for maneuvering rather than protection.

Explains how different feeders may connect through these switches, indicating potential issues if one feeder experiences problems.

Managing Power Supply During Maintenance

Outlines procedures when maintenance is needed on one feeder while ensuring continued power supply through another line.

Stresses the need for proper management during outages to maintain service continuity for users connected to trunk lines.

Grounding Techniques for Lightning Rods

Discusses grounding cable installation techniques using a small loop effect opposite the lightning rod's direction.

Understanding Grounding Systems in Electrical Installations

Function of Automatic Disconnectors

The automatic disconnector operates when excess energy is present, draining it to the ground through a grounding cable.

A steel cable with a twisted end connects to the automatic disconnector, which plays a crucial role during electrical surges.

Impact of Electrical Surges

Brief electrical surges can occur without affecting normal operations; however, repeated electromagnetic disturbances (like lightning) can degrade grounding characteristics.

If defects arise in the system due to these disturbances, current may leak and create short circuits with the ground.

Consequences of Short Circuits

The presence of explosive materials near grounding systems can lead to overheating and potential explosions if short circuits occur.

Properly functioning lightning rods are designed to handle multiple electrical surges but may lose insulating properties over time.

Installation Guidelines for Grounding Cables

Grounding cables should be installed with a slight bend (resembling a spring effect), opposing the direction of the lightning rod for optimal performance.

Structural Considerations in Electrical Networks

When changing conductor sizes, messenger cables must be installed to maintain structural integrity and prevent mechanical accidents.

The installation of messenger cables helps stabilize structures by distributing weight evenly across them.

Addressing Changes in Conductor Sizes

Differences in conductor sizes can cause imbalances that may lead to mechanical failures; thus, proper stabilization measures are essential.

Interconnection Points for Messenger Cables

Grounding Installation and Safety Measures

Temporary Grounding Procedures

The grounding installation is referred to as "messenger" in question number 32, which requires the installation of a stirrup loop with wedge-type connectors for temporary grounding.

It is established that every approximately 160 meters of network should have an installation point for the stirrup connector to ensure proper grounding in a semi-insulated network.

Emphasis on the necessity of using another wedge connector; improper grounding can lead to severe accidents due to inadequate electrical safety measures.

Connection Techniques

Each 160-meter segment of protected network must be opened up to install the stirrup connector for temporary grounding, ensuring safety at both ends of equipment handling and overcurrent protection.

The connection will involve all three phases, highlighting the importance of thorough grounding practices across multiple points in the system.

Safety Risks and Precautions

Discussion on serious risks associated with improper grounding; a tragic incident where an electrician lost his hands due to accidental energization emphasizes the critical nature of these safety protocols.

A warning about electricity's unpredictable nature—its lack of color or smell—and how quickly it can cause harm if not handled properly.

Importance of Grounding in Electrical Systems

Professional Responsibility

Electricians are urged to take their responsibilities seriously; understanding that knowledge about safe practices transcends just passing exams but is crucial for personal safety.

Reinforcement that professionals must ground systems effectively on both sides, emphasizing diligence when working with live electrical components.

Application in Distribution Networks

In question number 33, it’s specified that temporary grounding connectors should be installed at junction points protected by fuses.

An example illustrates where temporary grounding connectors should be placed within distribution networks, particularly near load sources.

Depth Requirements for Grounding Mesh

Urban vs. Rural Standards

Question number 34 addresses urban mesh depth requirements: a minimum depth of 300mm (30cm), contrasting with rural standards which require deeper installations (500mm).

Importance placed on correctly interpreting project specifications based on location (urban vs. rural), as misinterpretation could lead to incorrect installations and potential hazards.

Installation Insights

Installation of Grounding Cable in Structures

Overview of Grounding Process

The speaker discusses the grounding cable installation, emphasizing the importance of running the cable through the internal part of a straight angle bracket and securing it with a grounding connector.

Attention is drawn to a specific structure (C3), highlighting different perspectives on viewing the structure, which aids in understanding its layout during installation.

Structural Perspectives

The speaker describes observing the structure from various angles, including a profile view and a rear view, which are crucial for proper grounding installation.

A detailed explanation follows about passing the grounding cable internally within the straight angle bracket while ensuring secure connections at critical points.

Tensioning and Safety Measures

It is essential to keep the grounding cable tensioned to prevent contact with energized conductors, as this could lead to dangerous arcing or disturbances.

The necessity of maintaining tension on the grounded wire is reiterated to avoid issues like "trilhamento," which can occur if cables touch each other improperly.

Final Steps in Installation

The process continues with visualizing how cables pass through brackets and connect securely at designated points for effective grounding.

Emphasis is placed on ensuring that all components are correctly aligned and secured before finalizing installations.

Conclusion of Grounding Procedure

The speaker summarizes key steps taken during installation, reinforcing how to properly ground using internal cabling methods within structures.

Amarrações e Ancoragens na RDP

Tipos de Amarrações Utilizadas

O uso de amarrações e ancoragens na Rede de Proteção (RDP) é discutido, incluindo a utilização de super formado metálico como separador e espaçador para cabo mensageiro.

A alça preformada e o grampo de ancoragem polimérico são mencionados como opções para cabos cobertos, destacando a importância do grampo de ancoragem.

Fios de alumínio coberto são utilizados para amarração, além do isolador de pino que também é uma providência importante.

Exemplos Práticos

Um exemplo prático é apresentado com um anel de amarração e uma alça com cinco voltas, demonstrando a técnica correta para fixar cabos.

A amarração lateral em isoladores de pino é explicada, enfatizando sua aplicação em estruturas que permitem pequenas angulações.

Estruturas e Suportes

A estrutura dois permite deflexões triangulares, sendo ideal para esse tipo específico de amarração.

O tipo de amarração no topo do isolador é descrito como tangente à estrutura um.

Amarração do Espaçador Losangular

A forma da amarração do espaçador losangular no estribo é detalhada, mostrando a interação entre os suportes e o braço tipo L.

O uso atual do auto travante em vez da amarração convencional é mencionado, assim como a possibilidade de usar um anel para essa finalidade.

Distância dos Separadores Verticais

A distância recomendada para instalação do separador vertical em relação ao ponto de cruzamento da RDP é 1700mm, conforme indicado no projeto.

Understanding Network Terminations and Connections

Characteristics of Network Terminations

The discussion begins with the nature of network terminations, emphasizing that they should be independent. However, it is noted that certain networks may not qualify as final terminations due to their characteristics.

The speaker explains why surge protectors (para-raios) are not applied in specific cases where the involved networks share the same nature, indicating a lack of need for additional protection.

Cable Crossings and Specifications

An illustration is presented showing a real-life scenario involving cable crossings. The speaker highlights the importance of measuring distances accurately between vertical spacers and crossing points.

It is emphasized that the connection cable must have a larger diameter (bitola), ensuring it is heavier than those crossing over it. This principle helps maintain stability during operation.

A clear guideline is provided: smaller diameter cables should always cross above larger ones due to weight considerations, which aids in preventing potential issues during distribution.

Connection Techniques and Materials

The use of aluminum-covered cables is discussed, including techniques for securing connections using plastic clamps to prevent entanglement during movement or wind disturbances.

Various types of connectors used in compact networks are introduced, such as wedge connectors made from copper or aluminum with protective coatings. These ensure reliable connections within the network infrastructure.

Restoration Procedures for Cable Insulation

The process for restoring insulation on compact network cables after making derivations is outlined. It involves covering exposed conductors with insulating materials to prevent future disturbances from environmental factors.

Illustrations demonstrate how to properly cover joints using adhesive tape or heat-shrink tubing, ensuring all exposed areas are adequately protected against external elements like moisture and debris.

Network Connection and Cable Coverage

Material for Covering Connections

The discussion begins with the importance of using a solid, reliable material for covering connections in compact networks, likening it to a strong insulating tape.

Clarification is made between covering connections and splices; the focus is on how to cover an end of a cable when connecting it to a connector.

An image is referenced that illustrates the type of connector (wedge type) used in network derivations, emphasizing the need for proper coverage.

Protective Measures for Connectors

It’s highlighted that protective coverings should be applied over all connections to ensure safety and reliability.

Specific materials like self-adhesive wraps are recommended for use with wedge connectors, especially in grounding applications or temporary setups.

Importance of Proper Coverage

A warning is issued about potential hazards if connections are not properly covered; overheating can lead to dangerous situations such as hot spots.

The speaker stresses that maintaining proper coverage helps prevent issues like network failures or accidents due to exposed wiring.

Tension Calculations in Compact Networks

Maximum Allowable Tension

The maximum allowable tension for calculating traction tables in compact networks is discussed, advising attention to specific details provided during assessments.

Key figures are presented: maximum tension ranges from 8% to 10% of rupture tension at different temperatures and conditions.

Understanding Traction Values

Details on sagging corresponding to temperature variations are shared, indicating how these factors influence cable performance under load.

The speaker explains that the messenger cable has a rupture tension around 4,900 daN, which serves as a baseline for calculations regarding safe operational limits.

Cable Formation and Characteristics

Structure of Cables Used

The formation of cables utilized in compact networks includes three phase conductors typically rated at 50 mm² alongside a messenger wire made from steel (9.5 mm).

Distinction Between Cable Types

Differences between single-phase and three-phase circuits are clarified; emphasis is placed on ensuring correct identification of conductor sizes and types used within these systems.

Characteristics of Protected Cables

Features of Protected Cables

Characteristics include extruded polymeric protective coverings designed specifically for electrical applications. This ensures durability and safety against environmental factors.

Importance of Extrusion Process

Characteristics of Protected Cables in Electrical Networks

Reducing Leakage Current

The design of the cable aims to reduce leakage current during accidental contact with grounded objects, which is crucial for safety.

Spacing and Material Composition

The spacing between conductors in this protected network is significantly smaller compared to conventional networks, enhancing efficiency.

The cable's outer covering is made from cross-linked polyethylene (XLPE), a thermoset material known for its durability.

Resistance to Electrical Tracking

The cables exhibit resistance to electrical tracking, which occurs when conductive paths form on the insulation due to moisture or contamination.

Cable Thickness Specifications

According to standards, the average thickness of the cable cover must be 3 mm regardless of the conductor's cross-sectional area. This specification ensures uniformity and reliability across different installations.

Understanding Blocked Conductors

Blocked conductors are designed with their interstices filled along their length to prevent water ingress, ensuring longevity and performance under various conditions.

Design Features Against Water Ingress

A blocked conductor prevents water from entering by filling gaps along its length; this design feature is critical for maintaining functionality in wet environments.

Impedance and Traction Criteria in Compact Networks

Managing Water Accumulation Risks

Properly designed conductors minimize interstitial spaces that could collect water, reducing risks associated with moisture accumulation.

Traction Control Mechanisms

The traction applied to messenger cables must be controlled using a dynamometer, ensuring that forces remain within safe limits during installation or maintenance activities.

Importance of Messenger Cables

Only messenger cables are subject to tractive forces; phase conductors remain suspended without direct tensioning, highlighting a key aspect of network design.

Design Standards for Protected Network Components

System Specifications

Cables and accessories are engineered for normal service conditions within a three-phase system at 60 Hz frequency, adhering strictly to national standards.

Voltage Classifications

The system operates at specific voltage levels such as 13.8 kV phase-to-phase and 7.9 kV phase-to-ground, indicating robust infrastructure capable of handling medium voltage applications.

Network Protection and Operating Conditions

Temperature Ranges for XLPE Cables

The normal operating temperature range for the network is between 0 to 40 degrees Celsius, which is essential for proper functioning.

XLPE cables can withstand a permanent operating temperature of up to 90 degrees Celsius without deforming or melting.

In case of a short circuit, XLPE can handle intermittent temperatures reaching up to 250 degrees Celsius for very brief periods (milliseconds).

After a short circuit event, if the temperature stabilizes at 250 degrees Celsius, the cable will still support this condition temporarily.

Humidity and Altitude Considerations

A minimum relative humidity of 60% is necessary for optimal system performance; higher humidity levels may lead to operational disturbances.

The installation altitude should not exceed 1,200 meters above sea level to ensure safety and functionality.

Environmental Exposure

The network must be designed to endure exposure to sunlight and rain under normal service conditions without compromising its integrity.

Closing Remarks

The speaker expresses gratitude towards viewers for their support and encouragement in creating educational content.