CEMIG l ND 2.2 l Aula 02 l Instalações Básicas de Redes de Distribuição Aéreas Rurais

Introduction to Video Lesson 2

Overview of the Course

• The video is the second lesson in a series focused on electricity and safety, specifically related to rural distribution networks.

• The instructor expresses gratitude towards followers on social media and emphasizes the importance of understanding cable specifications.

Understanding Cable Specifications

Types of Cables Discussed

• The discussion highlights five types of cables used in rural distribution, referencing ND 2.2 standards for clarity.

• Specific cable sizes are mentioned: 21mm² (4 AWG), 54mm² (1 AWG), and 107mm² (4/0 AWG), along with their applications.

Structural Requirements for Three-phase Systems

Installation Guidelines

• For three-phase structures with an MBI of 300kV, it is required to use poles that are at least 1 meter tall for anchoring.

• Visual aids are provided to illustrate how these poles should be positioned in relation to monophase structures using specific cable types.

Insulator Standards

Types and Usage

• Insulators made from Pinus wood are standardized; porcelain insulators for both 15kV and 36.2kV systems are discussed.

• Older insulators can still be utilized as long as they meet structural requirements, despite newer polymer options being available.

Derivation Structures in Rural Distribution

Implementation Strategies

• Derivations must follow specific guidelines; they should not connect directly but rather oppose existing lines to maintain system integrity.

Understanding Post Derivations and Key Electrical Concepts

Importance of Post Structure in Supporting Network Weight

• The discussion begins with the need to resize a post to support the weight of the network, emphasizing that adjustments must compensate for the absence of style.

• It is clarified that only two derivations are permitted per post, one on each side, as stated on page 7.1.

Visualizing Derivations and Their Limitations

• An animation illustrates that a crossbeam can have one derivation leading to each side, reinforcing the maximum limit of two derivations per post.

• The speaker explains that even if multiple posts exist, only one set of switches can be installed at a structure with two derivations.

Installation Guidelines for Switches

• If there are two derivations on a single post, additional switches must be placed at least 80 meters away from the original structure.

• This distance requirement ensures safety and compliance with installation standards.

Distance Regulations for Transformer Connections

• A switch can be located up to 500 meters from a transformer as long as it remains visible from that location.

• The importance of visibility is highlighted to prevent potential hazards caused by improper placement of switches relative to transformers.

Understanding Repeater Fuses in Monophase Transformers

• The use of repeater fuses is discussed; they can be utilized in monophase transformers under specific conditions.

• A video link will provide further insights into how these fuses operate within electrical systems.

Functionality and Operation of Repeater Fuses

• The speaker references an existing video detailing how repeater fuses function, particularly their role in rural settings.

• A detailed explanation follows about how these fuses interrupt circuits during overload situations, ensuring system safety.

Conclusion: Practical Applications and Safety Measures

• Emphasis is placed on understanding circuit interruption mechanisms through practical demonstrations shared in training sessions.

Key Concepts in Electrical Installation

Overview of Electrical Components and Connections

• The discussion begins with the explanation of a specific electrical setup involving a conductor that combines three pieces into a single phase, allowing for multiple switches (19 keys) across different phases.

• A focus on the maximum conductor size for connecting to a fuse switch is introduced, referencing regulatory standards from Cemig, which specify a maximum size of 50 mm².

• The speaker emphasizes using rigid cables for connections and illustrates the use of 50 mm or 1/0 AWG cables as examples for installations involving fuse switches.

Installation Guidelines and Restrictions

Rebaixamento (Lowering) Regulations

• Clarification on the prohibition of lowering longitudinal fixations on poles during installations; this is critical to maintaining structural integrity.

• It is reiterated that lowering fixations in any form on certain pole types (poles de ter) is not allowed under any circumstances.

Structural Conditions for Installations

• The conditions required for structures classified as M41 are discussed, particularly regarding deflection angles not exceeding 10 degrees in trunk lines.

• Emphasis on maintaining a minimum distance of 200 mm between longitudinal states and crossbars to ensure stability and compliance with installation standards.

Specific Installation Requirements

Key Switches and Fuse Placement

• Instructions indicate that AM3 must exit at a right angle from the trunk line, ensuring proper alignment within the structure's design.

• Restrictions are placed on installing knife switches or repeated fuse switches within certain circuits due to safety concerns; only specific types can be used based on their configuration.

Conditions for Repeated Fuse Switches

• For installations involving repeated fuse switches, they must be positioned correctly alongside conductors to maintain operational efficiency and safety protocols.

Installation Guidelines for Electrical Equipment

Installation of Lightning Rods

• The installation of lightning rods must be at least 250 mm from the opposite end of the crossarm to protect specific equipment.

• The lightning rod should be positioned on the same side as the switchgear but at the rear, ensuring it does not obstruct visibility or functionality.

Conditions for Installing Switches and Repeaters

• When installing switches in a 3D 95kV DMBI structure, they must face towards the network's derivation direction; placing them incorrectly can lead to operational issues.

• If a designer opts to include a lightning rod, it should be placed behind the switchgear rather than on the same side.

Weight Limitations for Simple Masts

• For installations using simple masts on wooden poles rated at 300 Dan, weight limits are crucial: 600 kg for wooden poles and 400 kg for other types.

• A simple mast supports various equipment like transformers and relays; understanding its weight capacity is essential for safe operations.

Equipment Handling Procedures

• For equipment exceeding specified weight limits during installation or removal, use hydraulic vehicles (e.g., Munck trucks) instead of simple masts to ensure stability.

Connection Requirements for Electrical Equipment

Specifications for Jumpers

• Jumpers (or "japs") used in electrical connections must adhere to specific diameter requirements based on voltage ratings.

• For cables up to 15,000 volts, covered cables with certain specifications (like AWG sizes and square millimeters) are mandatory.

Conditions for Repeater Installation Points

• The installation point of repeaters must have a maximum short-circuit level of 2,000 amperes asymmetrical and an obligatory fuse link rating of either 40T or 40K.

Regulator Installation Standards

Requirements for Regulators

• Regulators should be installed on concrete poles rated at 12m600 decanewtons. These poles provide better support due to their circular design.

Capacitor Protection Fuses

150k VR and Fuse Links

Use of Fuse Links in High-Power Equipment

• The speaker discusses using a 6k fuse link for high-power equipment, specifically mentioning a capacitor bank rated at 300kb R.

• For another capacitor bank rated at 600 chain R, a 25 fuse link will be utilized.

Transformer Installation Requirements

• The minimum height for installing a single-phase transformer is specified as 11 meters with an anchoring depth of 1.80 meters.

• If utilizing an existing post of the same height (11m300), the anchoring can be adjusted to either 1.70 or 1.60 meters.

Conductors and Insulators

Anchoring Conductors in RBS

• The method for securing primary conductors involves using preformed loops, particularly for neutral conductors.

• An image illustrates how the cable passes through an anchor point, emphasizing the importance of proper anchorage.

Types of Insulator Connections

• The discussion includes various types of insulator connections such as pin insulators and suspension insulators, highlighting their specific uses.

• It is noted that preformed loops are mandatory when making connections with pin insulators.

Connection Systems and Grounding

Connection Types According to Standards

• Different connection systems are outlined, including compression connectors made from aluminum and pressure terminals that are copper-plated.

• Additional connection types include compression sleeves for aluminum cables and steel-aluminized wires.

Grounding Criteria in Structures

• Normal grounding should alternate between structures when spans are less than or equal to 200 meters; this applies regardless of whether they are guyed structures.

Transformers and Grounding Techniques

Overview of Transformer Grounding

• The grounding for transformers is established using a steel cable, specifically 6.4 mm in diameter, connected with an H-type connector.

• A single-phase transformer setup is described, highlighting the connection from the switch to the transformer's bushing and emphasizing that both conductors are isolated.

Connection Procedures

• The grounding procedure involves placing the steel cable beneath the transformer, ensuring proper isolation as per regulations.

• Variations in connectors may exist depending on regional standards; however, the fundamental procedure remains consistent across different utility companies.

Installation Guidelines for Multiple Grounding Sets

• When installing multiple grounding sets, a minimum distance of 25 meters and a maximum of 100 meters between them is required.

• Each grounding set must be interconnected with additional conductors to form a unified grounding network.

Enhancing Grounding Efficiency

• Increasing the number of grounding sets improves overall system grounding effectiveness; maintaining a distance of approximately 3 meters between individual ground rods is recommended.

• It’s crucial to ensure that all connections respect specified distances to maintain safety and functionality.

Depth Requirements for Ground Connections

• The depth for burying cables should be at least 500 mm (50 cm), emphasizing precision in measurements typically expressed in millimeters for accuracy.

Grounding Around Fences

Distance Regulations Between Ground Rods

• For fence-related grounding systems, specific distances are outlined based on project specifications found on page 11 of relevant documentation.

Safety Considerations with Fence Installations

• Proper installation ensures that fences do not interfere with electrical networks; incorrect placements can lead to hazardous situations where fences become energized due to nearby electrical disturbances.

Isolation Devices in Electrical Systems

Understanding Electrical Safety in Agricultural Settings

Overview of Electrical Infrastructure

• The speaker describes the layout of an electrical network, emphasizing a servitude area that spans 15 meters across. This area is crucial for safety and maintenance.

• Discussion on grounding points within the network, highlighting the importance of maintaining proper potential differences to prevent accidents during short circuits.

Short Circuits and Their Implications

• Explanation of how increased amperage occurs during a short circuit, which can lead to fuse failure and energy interruption in the network.

• The role of grounding in managing excess energy flow during faults, ensuring safety by breaking the circuit when necessary.

Servitude Area Specifications

• Clarification on the dimensions of servitude areas: 7.5 meters from each side of a pole totals 15 meters. This is essential knowledge for compliance with safety regulations.

• Importance of understanding distances between fences and electrical networks; specifically noting that parallel structures should maintain a distance of 250 meters.

Fence Electrification Considerations

• The speaker highlights that when dealing with parallel fences, seccionadores (cut-off switches) are required at intervals to ensure safety along the perimeter.

• Visual representation provided to illustrate how electric fencing interacts with surrounding infrastructure, stressing that not all sections need electrification if they are sufficiently distanced.

Compliance with Normative Guidelines

• Emphasis on adhering to normative guidelines regarding installation practices for both monophase and triphase distribution networks within specified distances (30 meters).

• Discussion about bifurcated fencing systems around farms needing appropriate grounding measures every 250 meters for enhanced safety.

Safety Precautions During Maintenance

• A warning about potential hazards when working near broken cables; even if cables appear inactive, they may still be energized due to closed switches elsewhere in the system.

Understanding Cable Installation Techniques

Types of Cables Used in Structures

• The discussion begins with the importance of understanding cable types used in installations, specifically mentioning the HS 9.5 mm steel cable as a standard reference.

• The HS 9.5 mm cable is highlighted as the specific type utilized for structures by Cemig, emphasizing its significance in ensuring structural integrity.

Fixation Methods for Cables on Poles

• A visual representation illustrates how cables are fixed to poles, noting that the Sky cable wraps around the pole twice and connects at a 45° angle.

• It is essential to connect the neutral wire properly to enhance safety and compliance with regulations; improper connections can lead to issues.

• The fixation method involves using metal plates and connectors to secure cables effectively while preventing damage from tension.

Materials and Depth for Anchor Stays

• Various materials can be used for anchor stays, including wooden posts or steel plates, depending on local utility practices (e.g., Coelba).

• The required depth for anchoring these stays is specified as 1.20 meters (1200 mm), with a width of approximately 30 cm needed for excavation.

Height Regulations for Cable Installations

• Minimum height requirements dictate that cables must be at least 6 meters above ground level throughout their length, ensuring safety in various environments.

• In rural areas where terrain may vary significantly, alternative arrangements may be necessary to maintain this height requirement.

Adjustments for Sloped Terrain

• When dealing with steep or uneven terrain, adjustments must be made; anchors should be placed at a 90° angle relative to the post.

• For effective stabilization on sloped land, additional support posts may need to be installed at a 45° angle relative to existing structures.

Study Material Overview

Finalizing ND 2.2 Study

• The speaker discusses the necessity of using a counterpoint to create a contrast, emphasizing its importance in understanding the material presented.

• Reference is made to specific content found on page 12 and 9 of the ND 2.2 document, indicating where viewers can find relevant images and information.

• The session concludes with gratitude for engagement with the material, highlighting a positive reception from the audience.

Encouragement and Future Content

• The speaker expresses appreciation for support towards their channel, encouraging viewers to contribute via donations if they wish.

• Well wishes are extended to students for their studies and upcoming exams, promoting a supportive learning environment.