Transformer Components and Basics
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Transformer Components and Basics

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Questions and Answers

What is one key function of a transformer in electrical systems?

  • Increase resistance in circuits to reduce power loss
  • Convert direct current (DC) to alternating current (AC)
  • Store energy in capacitors for later use
  • Alter voltage levels to facilitate energy transport (correct)

    • Which of the following components is not part of a basic transformer design?

  • On-load tap-changer
  • Three-limb core
  • Variable resistor (correct)
  • Protective relay

    • Why can a transformer only operate with alternating current (AC)?

  • DC cannot be transformed by electromagnetic induction (correct)
  • AC provides the necessary phase shift for operation
  • The magnetic field in DC circuits does not collapse
  • AC allows for a continuous flow of electrons

    • What does the Buchholz relay in a transformer do?

    <p>Detects gas buildup from overheating</p> Signup and view all the answers

    In addition to voltage transformation, what other aspect does a transformer efficiency relate to?

    <p>The losses during energy transfer</p> Signup and view all the answers

    What is the purpose of using a positive dry gas pressure during transport of transformers?

    <p>To preserve the integrity of the active part during transport</p> Signup and view all the answers

    Which of the following is included in the commissioning process of transformers?

    <p>Extensive electrical testing and oil filling</p> Signup and view all the answers

    What kind of measurements are taken during the commissioning of transformers?

    <p>Comparative electrical measurements with factory data</p> Signup and view all the answers

    For larger transformers, what is the appropriate condition before transportation?

    <p>Transport them empty of oil with positive gas pressure</p> Signup and view all the answers

    What is the significance of creating a fingerprint during electrical measurements?

    <p>It provides unique data for future measurements and comparisons</p> Signup and view all the answers

    What is one of the main risks associated with porcelain bushings in transformers?

    <p>Fire hazards due to oil leakage</p> Signup and view all the answers

    Which risk from porcelain bushings is most likely to be aggravated by terrorist activities?

    <p>Breakages due to external damage</p> Signup and view all the answers

    What is a significant contributor to transformer failures?

    <p>Bushing insulation issues</p> Signup and view all the answers

    What maintenance action is necessary for porcelain bushings to ensure reliability?

    <p>Routine cleaning and washing</p> Signup and view all the answers

    What is the overall risk of a large power transformer failing after one year of service?

    <p>1%</p> Signup and view all the answers

    Which feature of porcelain bushings is considered a disadvantage?

    <p>Weak bending strength</p> Signup and view all the answers

    What proactive measure can enhance transformer reliability according to bushing fleet management principles?

    <p>Anticipating aging trends within the bushing fleet</p> Signup and view all the answers

    Why are porcelain bushings not recommended for horizontal mounting?

    <p>Their fragility makes them prone to failure in that position.</p> Signup and view all the answers

    What is the main purpose of transposing the coils during the winding process?

    <p>To maintain low eddy current loss.</p> Signup and view all the answers

    What is the significance of major insulation in the core coil assembly?

    <p>It addresses the capability to withstand high voltages.</p> Signup and view all the answers

    Which factor is a consequence of frequent loading and unloading of the transformer?

    <p>Development of tensile stress on the windings.</p> Signup and view all the answers

    During the ovening and drying process, why is drying considered essential for transformer insulation?

    <p>To prevent moisture from weakening insulation properties.</p> Signup and view all the answers

    What are the two types of drying techniques used in transformer manufacturing?

    <p>Air drying and vacuum drying.</p> Signup and view all the answers

    What does the construction of the core coil assembly (CCA) influence?

    <p>The insulation and cooling schemes of the transformer.</p> Signup and view all the answers

    What type of support does the construction of CCA provide to the transformer?

    <p>Radial and axial supports to prevent winding damage.</p> Signup and view all the answers

    What is a potential failure mode at high voltages if insulation properties are compromised?

    <p>Electrical flashing.</p> Signup and view all the answers

    What is the purpose of inspecting a transformer upon arrival at a factory?

    <p>To verify it was manufactured correctly and is in satisfactory condition.</p> Signup and view all the answers

    Which specification is NOT typically included on a transformer's nameplate?

    <p>Environmental impact ratings.</p> Signup and view all the answers

    Why might transformers over 500 MVA deviate from the optimum iron/copper ratio?

    <p>To meet shipping weight constraints.</p> Signup and view all the answers

    What is one of the risks associated with transporting transformers?

    <p>Physical damage due to inadequate rigging.</p> Signup and view all the answers

    What adjustments might be made to a transformer's oil level for transport?

    <p>Lower the oil level or empty the vessel.</p> Signup and view all the answers

    Which type of transport vehicle can carry a transformer weighing up to 500 tons?

    <p>Schnabel car with a through-loading beam.</p> Signup and view all the answers

    What is the benefit of enclosing transformer cabinets with transport boxes?

    <p>To protect the components from environmental damage.</p> Signup and view all the answers

    What is a common practice for ensuring transformer safety during transportation?

    <p>Filling the vessel with dry air or nitrogen.</p> Signup and view all the answers

    Which component is primarily responsible for maintaining oil levels within a transformer?

    <p>Conservator</p> Signup and view all the answers

    Which of the following statements is true regarding transformer operation?

    <p>Transformers allow energy transportation by changing voltage.</p> Signup and view all the answers

    What role does the on-load tap-changer play in a transformer?

    <p>It allows for voltage regulation while the transformer is under load.</p> Signup and view all the answers

    Which component is NOT a functional part of a transformer's core?

    <p>Motor-drive unit</p> Signup and view all the answers

    What is a critical effect of using alternating current (AC) in transformer operation?

    <p>AC enables the transformer to operate through electromagnetic induction.</p> Signup and view all the answers

    What is the maximum lifetime of a transformer bushing according to its design?

    <p>25 years</p> Signup and view all the answers

    What is a key feature of the Secondary insulation used in OIP bushings?

    <p>Oil</p> Signup and view all the answers

    Which component is NOT associated with the design of RIP (Resin Impregnated Paper) bushings?

    <p>Porcelain insulator</p> Signup and view all the answers

    What modification is necessary for using the new bushing with larger draw lead size?

    <p>Adjust the distance to ground</p> Signup and view all the answers

    What is the primary material used for the core insulator in RIS bushings?

    <p>Resin Impregnated Synthetic</p> Signup and view all the answers

    How does the risk of incidents associated with transformer bushings change with age?

    <p>Increases progressively with age</p> Signup and view all the answers

    What type of secondary insulation is used in RIP bushings?

    <p>Gas</p> Signup and view all the answers

    Which design feature distinguishes OIP bushings from RIP and RIS bushings?

    <p>Use of oil as insulation</p> Signup and view all the answers

    What effect does a magnetic core have on the strength of the magnetic field in an electromagnetic coil?

    <p>It increases the magnetic field strength several times.</p> Signup and view all the answers

    What is a primary consequence of using magnetic cores in AC devices?

    <p>They cause energy losses due to core losses.</p> Signup and view all the answers

    Which insulation property helps prevent localized hotspots within a transformer winding?

    <p>Insulation aids in heat conduction and distribution.</p> Signup and view all the answers

    What type of magnetic material is commonly used in transformer cores due to its low coercivity?

    <p>Silicon steel or ferrite.</p> Signup and view all the answers

    What role does insulation material play in the mechanical support of transformer windings?

    <p>It secures and supports conductors, preventing movement.</p> Signup and view all the answers

    How does insulation control electric field distribution within a transformer?

    <p>By reducing uneven electric field intensities.</p> Signup and view all the answers

    What is one of the side effects of using a magnetic core in transformers?

    <p>Reduced efficiency due to core losses.</p> Signup and view all the answers

    What benefit does winding insulation provide in terms of noise reduction within a transformer?

    <p>It reduces vibration and noise in the winding.</p> Signup and view all the answers

    What role does the current transformer serve in the winding thermometer mechanism?

    <p>It provides a current signal proportional to load current.</p> Signup and view all the answers

    Which statement accurately describes the function of a dehydrating breather in transformers?

    <p>It prevents moisture absorption from ambient air.</p> Signup and view all the answers

    What is a major benefit of maintenance-free dehydrating breathers compared to conventional ones?

    <p>They automatically remove moisture without external intervention.</p> Signup and view all the answers

    How does the winding thermometer indicate temperature changes?

    <p>By utilizing a gas-filled bellow mechanism.</p> Signup and view all the answers

    Which of the following is NOT a function of the transformer dehydrating breather?

    <p>Regulating oil levels in the expansion tank.</p> Signup and view all the answers

    What is a critical aspect of the self-learning algorithm in maintenance-free breathers?

    <p>It adapts to changing environmental conditions.</p> Signup and view all the answers

    Which impact does the heating of the measurement bellow have on the winding thermometer?

    <p>It results in increased indicator movement during higher loads.</p> Signup and view all the answers

    How do maintenance-free dehydrating breathers help in reducing operational costs?

    <p>Through self-regeneration and continuous dehumidification.</p> Signup and view all the answers

    Which of the following safety equipment is NOT required when working on transformers?

    <p>High-visibility vest</p> Signup and view all the answers

    What is the first step a user must take before starting work on a transformer?

    <p>Shut down the transformer</p> Signup and view all the answers

    Which action is NOT part of the protective measures for transformer safety?

    <p>Verify energized state</p> Signup and view all the answers

    During transformer training, how is the practical training session structured?

    <p>It includes visual inspection and oil processing.</p> Signup and view all the answers

    Which of the following is NOT a part of the transformer training agenda?

    <p>Thermal imaging diagnostics</p> Signup and view all the answers

    What does the employee count of 4,000 at Maschinenfabrik Reinhausen GmbH indicate?

    <p>A collaboration with 61 nationalities</p> Signup and view all the answers

    What is the significance of providing a safeguard to the deluge sprinkler or CO2 units?

    <p>Prevent fire outbreaks in the workplace</p> Signup and view all the answers

    Which of the following describes a key feature of the company mentioned?

    <p>It is a family-owned business since 1868.</p> Signup and view all the answers

    What is the purpose of grounding visibly and ensuring the proper cable cross-section?

    <p>To prevent electric shock hazards</p> Signup and view all the answers

    What type of hazard is prevented by switching off oil and water pumps?

    <p>Electrostatic charging hazards</p> Signup and view all the answers

    How many locations does Maschinenfabrik Reinhausen GmbH operate in?

    <p>60</p> Signup and view all the answers

    Which of the following is a benefit of having 28 subsidiaries and 11 joint ventures globally?

    <p>Enhanced local market knowledge</p> Signup and view all the answers

    What does the term 'AAA' signify for the company in terms of finance?

    <p>Highest credit rating</p> Signup and view all the answers

    Which statement accurately represents the training schedule on the second day?

    <p>It includes routine services and maintenance strategies.</p> Signup and view all the answers

    The maximum rated voltage for transformers can reach up to 52 kV.

    <p>True</p> Signup and view all the answers

    Almost 50% of all serious transformer fires are initiated by the failure of silicon composite bushings.

    <p>False</p> Signup and view all the answers

    Creepage distance for transformers can range from 505 mm/kV to 1,690 mm/kV.

    <p>True</p> Signup and view all the answers

    The partial discharges in transformers are considered high according to IEC 60137 standards.

    <p>False</p> Signup and view all the answers

    The transformer failure risk is estimated to be as high as 0.5% each year of service.

    <p>False</p> Signup and view all the answers

    An on-load tap-changer includes an OLTC oil compartment as one of its components.

    <p>True</p> Signup and view all the answers

    Counterfeit bushings are likely to have superior mechanical strengths compared to genuine OIP bushings.

    <p>False</p> Signup and view all the answers

    Transformers with a clamping interface conform to DIN 42538 standards.

    <p>True</p> Signup and view all the answers

    A De-Energized Tap-Changer (DETC) can operate while the transformer is energized.

    <p>False</p> Signup and view all the answers

    On-Load Tap-Changer (OLTC) allows for uninterrupted switching operations while the transformer is on.

    <p>True</p> Signup and view all the answers

    The Semiconductor Tap-Changer is known for its wear-free switching operations.

    <p>True</p> Signup and view all the answers

    The High-Speed Resistor-Type Tap-Changer was patented by Dr.A.

    <p>False</p> Signup and view all the answers

    DETCs are typically operated automatically without human intervention.

    <p>False</p> Signup and view all the answers

    The Reactor-Type Tap-Changer is designed for make-before-break switching operations.

    <p>True</p> Signup and view all the answers

    The On-Load Tap-Changer (OLTC) can be operated manually at any time.

    <p>False</p> Signup and view all the answers

    DETCs are highly complex and require regular maintenance.

    <p>False</p> Signup and view all the answers

    All types of tap changers require the transformer to be de-energized for operation.

    <p>False</p> Signup and view all the answers

    The Tap Changer using semiconductor technology operates inside the transformer.

    <p>False</p> Signup and view all the answers

    The VACUTAP® technology allows for contact life exceeding 600,000 tap-change operations.

    <p>False</p> Signup and view all the answers

    Conventional technology tap changers extinguish the arc in a vacuum interrupter.

    <p>False</p> Signup and view all the answers

    The diverter switch insert is a critical assembly in a high-speed resistor-type tap-changer.

    <p>True</p> Signup and view all the answers

    An electric switch with several switching positions is known as a circuit breaker.

    <p>False</p> Signup and view all the answers

    In a transformer, the tap changer is responsible for altering the winding ratio, thus affecting voltage output.

    <p>True</p> Signup and view all the answers

    The oil compartment in a transformer tap changer aids in insulating and cooling.

    <p>True</p> Signup and view all the answers

    A tap changer can only be built for a single phase operation.

    <p>False</p> Signup and view all the answers

    Mineral oil used in transformers is primarily responsible for switching gases formation.

    <p>False</p> Signup and view all the answers

    The aging of OLTC insulating oil is a crucial factor that affects tap changers.

    <p>True</p> Signup and view all the answers

    Formation of carbon bodies occurs during the switching process in high-speed resistor-type tap-changers.

    <p>False</p> Signup and view all the answers

    The maximum overload with the new bushing is 1.255 p.u.

    <p>False</p> Signup and view all the answers

    Bushing OLD has a current rating of 2.000 A.

    <p>True</p> Signup and view all the answers

    DGA results are not evaluated for COTA bushings.

    <p>False</p> Signup and view all the answers

    The transport box can be used to store the bushing in an inclined position.

    <p>True</p> Signup and view all the answers

    Moisture is one of the factors evaluated in the oil sampling from trench COTA bushings.

    <p>True</p> Signup and view all the answers

    The winding thermometer exclusively measures the top-oil temperature without considering the load current.

    <p>False</p> Signup and view all the answers

    Transformers equipped with dehydrating breathers do not need any maintenance to protect the insulating liquid.

    <p>False</p> Signup and view all the answers

    The movement of the measuring bellow in a winding thermometer is affected by a resistor that heats up due to current flow.

    <p>True</p> Signup and view all the answers

    The self-learning algorithm in maintenance-free dehydrating breathers is designed to reduce operating costs and not for monitoring the breathing cycle.

    <p>False</p> Signup and view all the answers

    Dehydrating breathers help to maintain the dielectric strength of the insulating medium by absorbing moisture from the surroundings.

    <p>True</p> Signup and view all the answers

    A transformer dehydrating breather can only remove a small portion of the moisture from the air due to its design limitations.

    <p>False</p> Signup and view all the answers

    The indicator in a winding thermometer is moved directly by the temperature of the load current without the influence of any mechanical components.

    <p>False</p> Signup and view all the answers

    The combination of current signal, resistor heating, and measurement bellow operates synergistically in transformer monitoring systems.

    <p>True</p> Signup and view all the answers

    Maintenance-free dehydrating breathers are less effective in humid climatic zones compared to conventional breathers.

    <p>False</p> Signup and view all the answers

    The transformation effectiveness of a winding thermometer is independent of the current transformer's signal when under load.

    <p>False</p> Signup and view all the answers

    Study Notes

    Transformer Main Components

    • Clamping
    • Frame
    • Conservator
    • HV Bushings
    • LV Bushings
    • Oil level indicator
    • Bevel gear unit
    • Buchholz relay
    • Protective relay
    • Pipes
    • Dehydrating breathers
    • Nameplate
    • Tap Leads
    • Tapped Winding
    • Tank
    • Motor-drive unit
    • Measurements
    • Three-limb core
    • LV Winding
    • HV Winding
    • Radiators
    • On-load tap-changer
    • Drive shafts

    Transformer Basics

    • Transformer only works with alternating current (AC)
    • Transformers allow voltage transformation
    • Transformers were key to AC winning the "current war"

    Transformer Mechanical Arrangement

    • Bushings are important components of transformers
    • Porcelain bushings used for voltage insulation have several risks:
      • Oil leakage and transformer fire
      • Breakages due to vandalism or terrorist attacks
      • Explosion and fragments due to electrical arcs
      • Need regular maintenance (cleaning & washing)
      • Fragility and difficult handling
      • Not recommended for horizontal mounting
      • While they have good compression strength, they have weak bending strength

    Increasing Transformer Reliability by Proactive Bushing Fleet Management

    • Aging transformers have a higher hazard rate
    • Transformer insulation failures are the most common, followed by winding issues
    • It is important to anticipate the aging trends of an installed transformer fleet

    HV Bushings life management importance

    • Bushings significantly contribute to transformer failures
    • The risk of a large power transformer failure is assumed to be up to 1% per year

    Transformer Manufacturing Process - Core Coil Assembly

    • The core coil assembly (CCA) is the winding assembly on the core and a vital part of the transformer
    • Construction of the CCA depends on insulation, cooling, dynamic withstand capability, and handling
    • Insulation scheme is categorized into major (high voltage) and minor (turn and joint)
    • The CCA must withstand tensile stress from frequent loading and unloading
    • The assembly design must be easy to handle for lowering into the tank and vice versa

    Transformer Manufacturing Process - Ovening and Drying

    • The drying process is important in transformer manufacturing
    • Paper and wood-based insulation materials absorb moisture, which weakens insulation and reduces resistance to high voltages
    • Two drying types: Air drying and vacuum drying

    Transformer Manufacturing Process - Inspection

    • Before accepting a transformer shipment, there are several inspections to perform
    • Electrical tests are essential to verify the unit's functionality
    • The transformer nameplate provides information about the unit's ratings, impedance, voltages, phasing, temperature rise, oil type, weight, connection diagrams, manufacturer, model number/type, and serial number

    Transformer Transportation & Shipping - Transformer Rigging - Transport

    • The size of a transformer depends on its power
    • High power transformers often deviate from the optimum iron/copper ratio (2/1) due to transportability
    • Limits on the weight of transformers
    • Future challenges may arise in the transport of transformers

    Transformer Transportation & Shipping - Transformer Rigging - Transport Medium and Max.Weights

    • Flatbed trucks can transport up to 150 tons
    • Schnabel cars can transport up to 300 tons (with through-loading beam) or 500 tons
    • Roll-on/Roll-off can transport up to 500 tons

    Transformer Transportation & Shipping - Transformer Rigging - Dismantling

    • Dismantling of feedthroughs and all interfering components during transport
    • Enclosure of cabinets with transport boxes
    • Lowering oil levels or emptying vessels
    • Filling with dry air or nitrogen for transport

    Transformer Transportation & Shipping - Transformer Rigging - Risks to Goods During Transport

    • Increased tendency to transport goods globally
    • Construction supervision
    • Technical support during installation and commissioning
    • Multi-year service contracts
    • Comprehensive electrical testing and oil filling during commissioning
    • Comparison of on-site measurements with factory measurements for future reference

    Transformer Commissioning & Installation - Transformer Rigging - Montage and Installation

    • Transformers with primary and secondary connections
    • Bushings
    • Conservator
    • Oil work
    • IBN tests
    • Oil sampling and analysis
    • Cooling system
    • Piping system
    • Protection and monitoring devices
    • Dome

    Transformer Commissioning & Installation - Transformer Riging - Transport

    • It is possible to transport small power transformers full or partially filled with oil
    • Larger transformers are transported empty of oil
    • Empty or partially filled transformers are put under a positive dry gas pressure before shipping
    • An automatic system ensures continuous positive pressure inside the transformer

    Working Safety on Transformers Equipment

    • Protective equipment includes helmets, goggles, work clothes, safety shoes, belts, ear protection, and electrical gloves.
    • The transformer must be shut down before starting work.
    • Grounding switch must be safeguarded to prevent accidental restart.
    • Verify de-energized state and ensure proper ground cable size and placement.
    • Mark hazard areas clearly.
    • Deluge sprinklers and CO2 units should be switched off.
    • Oil and water pumps should be switched off to prevent electrostatic charging hazards.
    • Suitable ladders should be used and tied securely.
    • Escape routes should be explained and shown.

    RME Transformer Training Agenda

    • Day 1 includes Introduction, Transformer Basics, Transformer Mechanical Arrangement, Oil Processing & Oil Reconditioning.
    • Day 2 includes Maintenance Strategies, Electrical Measurements, Routine Services, Oil Sampling & Oil analysis, Testing Oil reconditioning equipment.
    • Day 3 includes Taking oil samples, Testing of electrical equipment, Thermography, Testing thermography equipment, Visual Inspection, and Conclusion.

    MR at a Glance

    • MR is a family business since 1868, now in its sixth generation.
    • MR is a world market leader, with 50% of the world's electricity flowing through their products.
    • MR has a revenue of 1 billion euros in 2023.
    • The company has a AAA rating.
    • MR employs over 4,000 people of 61 nationalities at 60 locations.
    • MR has 8,000 customers in 185 countries.

    Transformer Basics

    • Transformers use alternating current (AC) and cannot operate with direct current (DC).
    • Magnetic fields are created by current-carrying coils.
    • Transformers are often used to change voltage levels.
    • Magnetic cores increase the strength of magnetic fields.
    • Magnetic cores cause energy losses due to hysteresis and eddy currents.
    • Transformer calculations help to understand the transformer's operation and efficiency.

    Transformer Mechanical Arrangement

    • Winding insulation protects conductors and coils from short circuits and ensures electrical safety.
    • Winding insulation provides mechanical support for the winding, preventing movement or vibration.
    • Insulation materials help to distribute and conduct heat evenly.
    • Insulation controls the distribution of electric fields, reducing uneven intensities.
    • Insulation materials reduce noise and vibration.

    Transformer Mechanical Arrangement - Protective Devices

    • The winding thermometer responds to both top-oil temperature and load current heating.
    • The winding thermometer provides an image of the hottest part of the winding.
    • Top-oil temperature is measured similarly to other methods.
    • Load current proportional to winding current is used, measured by a current transformer.
    • Current transformer's signal heats a resistor, which then heats the measurement bellow, increasing the indicator movement.

    Transformer Mechanical Arrangement - Dehydrating Breathers

    • Dehydrating breathers protect insulating liquids in transformers by preventing moisture absorption from ambient air.
    • Dehydrating breathers remove moisture from the air entering the conservator during cooling.
    • They prevent dielectric strength reduction and condensation formation.

    Transformer Mechanical Arrangement - Breathers vs. Maintenance-Free Breathers

    • Maintenance-free breathers continuously dehumidify and monitor breathing cycles in all climates.
    • They reduce operating costs and improve reliability.
    • They regenerate themselves, reducing costs and maximizing safety.
    • They protect insulation medium against humidity.
    • They use a condition-dependent and self-learning algorithm.
    • They are easy to retrofit.

    Transformer Bushing Replacement

    • HSP Bushings last approximately 25 years according to design.
    • The risk of incidents increases with age.
    • OIP Bushings are designed with oil-impregnated paper, oil, and porcelain/epoxy/silicone insulators.
    • RIP and RIS Bushings are designed with resin-impregnated paper/synthetic, gas/dry material filler, and epoxy resin/porcelain/silicone insulators.
    • OIP to RIP&RIS design requires modifications like larger draw lead size and increased distance to ground.

    Transformer Fire Risk

    • Transformer failure results in a serious fire in 10% of cases.
    • The risk of fire is as high as 0.1% for each year of service.
    • Almost 50% of serious transformer fires are connected to OIP bushing failures.
    • OIP bushing failure is considered the leading cause of transformer fires.

    Silicone Composite Bushing (SBC)

    • SBC is a type of transformer bushing that utilizes composite materials.
    • SBC replaces fragile porcelain insulators with a high-tech composite insulator.
    • SBC uses a fiber glass tube for superior mechanical strength.
    • SBC offers cantilever load and horizontal assembly capabilities.
    • The silicone molded coating provides electrical features compliant with IEC 137.

    SBC Technical Data

    • SBCs have a maximum rated voltage of 12 kV, 24 kV, 36 kV, and 52 kV.
    • Maximum rated currents range from 630 A to 4,500 A.
    • Creepage distance varies from 505 mm/kV to 1,690 mm/kV.
    • SBCs adhere to the IEC 60137 standard.
    • The clamping interface aligns with DIN 42538 and EN 50180.
    • SBCs produce low partial discharges, meeting IEC 60137 standards (< 10 pC).
    • Finish options include tin plating, silver plating, and other customizations.

    On-Load Tap-Changer (OLTC) Components

    • OLTC is composed of three main components: the motor-drive unit, accessories, and the OLTC itself.

    OLTC Components

    • The OLTC head includes a cover, pipe connections, a temperature sensor, a position indicator, a PRD flange with a pressure relief device, a blind flange, and an air bleed valve.
    • The OLTC oil compartment contains the tap selector, the interrupter exchange module, and resistors.
    • The tap selector uses a diverter switch insert (DSI).
    • The OLTC motor-drive unit is utilized for operation.

    Conventional vs. VACUTAP® Technology

    • Conventional OLTC technology utilizes oil to quench the arc.
    • VACUTAP® technology uses a vacuum interrupter for arc quenching.
    • Conventional technology has a contact life of 200,000 - 500,000 tap-change operations.
    • VACUTAP® technology offers a longer contact life of 600,000 tap-change operations.

    OLTC Operation

    • OLTCs function by adjusting the transmission ratio (winding ratio) in a transformer.
    • Changes in the transmission ratio affect the voltage ratio and output voltage.
    • OLTCs are designed for single, dual, or three-phase systems.
    • On-load tap changers allow uninterrupted switching under load.

    Tap Changer Types

    • Tap changers are electric switches with multiple positions for adjusting the transmission ratio.
    • De-energized tap changers (DETC) require the transformer to be switched off for operation.
    • On-load tap changers (OLTC) allow uninterrupted switching while the transformer is energized.
    • OLTCs include semiconductor, reactor-type, and high-speed resistor-type tap changers.

    Tap Changer Assemblies

    • A high-speed resistor-type tap changer consists of several assemblies: oil compartment, diverter switch insert, tap selector, and change-over selector/pre-selector.

    Tap Changer Operation

    • OLTCs provide the ability to adjust the output voltage of a transformer under load.
    • The adjustment is achieved by changing the number of turns on the winding through the tap changer.
    • The transformer is on during these adjustments, making OLTC's suitable for continuous operation.

    Winding Thermometer

    • The winding thermometer measures the heat generated in the transformer windings.
    • It provides an image of the hottest part of the winding, incorporating both top-oil temperature and load current.
    • The current signal is derived from a current transformer positioned inside the bushing.
    • This current heats up a resistor element, leading to an increase in the temperature of the measurement bellow, causing an indicator movement.

    Dehydrating Breathers

    • Transformer dehydrating breathers protect the insulating liquid from moisture absorption.
    • They remove moisture from the air entering the conservator as the transformer cools down.
    • This increases operational safety by preventing dielectric strength reduction and condensation in the expansion tank.

    Transformer Bushing Replacement

    • Transformer bushing replacements involve replacing old oil-immersed paper (OIP) bushings with resin-impregnated paper (RIP) or silicone rubber (RIS) designs.
    • This replacement aims to improve the transformer's reliability and performance.
    • Replacing OIP bushings with RIP or RIS designs can impact the transformer's load capacity.
    • It is crucial to carefully analyze the load requirements before proceeding with a bushing replacement.

    OIP Bushing Oil Samples

    • Oil samples collected from OIP bushings can provide valuable insights into the condition of the bushing.
    • Analyzing these samples using Dissolved Gas Analysis (DGA), breakdown voltage (BDV), and interfacial tension (IFT) measurements can identify potential issues such as moisture, sulphates, and other contaminants.

    Dehydrating Breather Installation

    • Maintenance-free dehydrating breathers offer continuous dehumidification and monitoring.
    • They provide benefits such as reduced operational costs, increased reliability, self-regeneration, active humidity protection, and easy retrofitting on existing equipment.

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    Transformer Training Reinhausen Middle East PDF

    Description

    Explore the essential components and principles of transformers in this quiz. Learn about the mechanical arrangements, functionality, and safety concerns associated with transformers. Test your understanding of how transformers contribute to voltage transformation and AC electricity.

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