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The on-load tap-changer cover must be removed to drain oil from the oil conservator.

True

What should be ensured when removing the dehydrating breather?

  • The oil temperature is above 100°C
  • No explosive gases are present (correct)
  • The room is ventilated
  • Oil is overflowing

    • The recommended oil content for the oil conservators takes into account a safety margin of ___%.

    50

    What components are included in the mobile oil filter unit OFP 010-SD?

    <p>4 hoses, 2 suction tubes, pipe adapter, operating instructions</p> Signup and view all the answers

    How many liters of Fuller's earth are recommended per diverter switch insert?

    <p>10 liters</p> Signup and view all the answers

    What is the purpose of the mobile oil filter unit?

    <p>To filter insulating oil</p> Signup and view all the answers

    The valves in the mobile oil filter unit can be set electronically.

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

    How are the oil conservators connected to the atmosphere?

    <p>Hermetically sealed transformer</p> Signup and view all the answers

    Were irregularities detected on the on-load tap-changer or transformer before the incident occurred?

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

    What does OLTC stand for?

    <p>On-load tap-changer</p> Signup and view all the answers

    What is the test standard for oil samples?

    <p>IEC or ASTM</p> Signup and view all the answers

    What types of circuit breakers are mentioned?

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

    Oil sample tests were carried out after the incident.

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

    The measured dielectric strength for IEC 156 is ___ [kV / 2.5 mm].

    <p>value not specified</p> Signup and view all the answers

    Which of the following options are methods for draining oil?

    <p>Using a pipe</p> Signup and view all the answers

    What does GIS mean?

    <p>Gas-insulated switchgear</p> Signup and view all the answers

    The switching oil of the on-load tap-changer is non-flammable.

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

    The oil sample was taken from the ___ compartment.

    <p>OLTC or transformer</p> Signup and view all the answers

    What is the correct valve position for the particle filter and moisture filter circulation?

    <p>Filter particles and moisture</p> Signup and view all the answers

    What should you do if the differential pressure of the fine particle filter reaches ≥1500 mbar?

    <p>Change the filter</p> Signup and view all the answers

    The coarse filter must be cleaned after every filtering process.

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

    The oil sample is used to determine ____ strength and water content.

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

    What is the recommended water content limit in ppm for the refilled oil?

    <p>≤15 ppm</p> Signup and view all the answers

    What should be done if the overall pressure of the oil filter unit exceeds 3.5 bar?

    <p>Switch off the unit</p> Signup and view all the answers

    What type of filter is type – SD-718 P3 used for?

    <p>Fine moisture filter</p> Signup and view all the answers

    The valve of the moisture filter is placed in the ____ condition.

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

    How much water absorption is a criterion for changing the fine moisture filter?

    <p>300 ml</p> Signup and view all the answers

    The replacement interval for OILTAP® M oil compartment contacts is _____ operations.

    <p>2,000,000 – 2,400,000</p> Signup and view all the answers

    Which of the following is true for OILTAP® MS?

    <p>No replacement is necessary when retrofitting to VM®.</p> Signup and view all the answers

    What happens to the diverter switch insert when the replacement interval for oil compartment contacts is reached?

    <p>The diverter switch insert should be retrofitted with VACUTAP® VM®.</p> Signup and view all the answers

    At what interval should the oil compartment contact for VACUTAP® VMS® be replaced?

    <p>Only within scope of selector maintenance</p> Signup and view all the answers

    ECOTAP® VPD® has a replacement interval for oil compartment contacts.

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

    Match the following ON-LOAD tap-changer types with their oil compartment contact replacement intervals:

    <p>OILTAP® M = 2,000,000 – 2,400,000 OILTAP® R = 800,000 VACUTAP® VM® = 2,000,000 – 2,400,000(2) VACUTAP® VRC = 1,200,000</p> Signup and view all the answers

    What should be entered on the service label applied inside the motor-drive unit after maintenance?

    <p>The date of maintenance and the number of operations performed.</p> Signup and view all the answers

    What does the checklist incident report require regarding the transformer data?

    <p>All of the above</p> Signup and view all the answers

    The date on the service label must be entered in the format MM/DD/YYYY.

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

    What is the diameter of the brown stains in the insulating material?

    <p>1 to 3 mm</p> Signup and view all the answers

    The brown stains in the insulating material result in damage to the surface.

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

    What should be used to smoothen damaged areas of insulating material?

    <p>Sanding paper with gradual grit (100 to 400) and transformer oil.</p> Signup and view all the answers

    What is the purpose of polishing and wipe-lacquering damaged GFRP surfaces?

    <p>To restore the integrity and appearance of the damaged area.</p> Signup and view all the answers

    What mixing ratio should be used for the lacquer and hardener?

    <p>50:50</p> Signup and view all the answers

    Dielectric tests are performed by CTTV at 50% of the rated power-frequency withstand voltage.

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

    Match the following measures to the respective features:

    <p>Net-like treeings of small dimensions = Abrade using sanding paper and transformer oil Carbon deposits non-removable = Remove using an eraser type Edding R20 Light brown discolorations in scratches = Light brown areas remain unchanged</p> Signup and view all the answers

    The light brown discoloration is a heating occurrence of the insulating material caused by ______.

    <p>surface currents</p> Signup and view all the answers

    What decision does the responsible OPS need to make regarding insulating materials?

    <p>About shortening the inspection intervals or potential replacement of insulating materials.</p> Signup and view all the answers

    What is the maximum length of creepage path for Type A?

    <p>50% of phase distance</p> Signup and view all the answers

    Type B creepage paths can have dark brown to black discoloration.

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

    What should be used to abrade Type C creepage paths?

    <p>Sanding paper, grit 100 to 400, and transformer oil.</p> Signup and view all the answers

    The responsible OPS will decide about shortening the inspection intervals or potential replacement of insulating materials for _____ type.

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

    What is the minimum action required if shutdown of the transformer is not possible until replacement for Type C?

    <p>Abrade creepage paths</p> Signup and view all the answers

    What is required for maintaining the integrity of the abraded areas?

    <p>Keep abraded area as small as possible.</p> Signup and view all the answers

    Match the type of creepage paths with their corresponding actions:

    <p>Type A = Abrade using sanding paper, grit 100 to 400 Type B = Keeps abraded area small Type C = Replace insulating material if possible Type D = Use scraper for deep paths</p> Signup and view all the answers

    Extensive creepage paths require replacing the insulating materials.

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

    What must be done before starting work on the on-load tap-changer cover?

    <p>All auxiliary circuits must be de-energized.</p> Signup and view all the answers

    Why should electrical devices not be used when working on the on-load tap-changer cover?

    <p>They may create spark formation.</p> Signup and view all the answers

    What is the first step in venting the switching gas from the on-load tap-changer cover?

    <p>Open the bleeder valve.</p> Signup and view all the answers

    What should be done immediately after venting the switching gas and when oil starts entering?

    <p>Close the bleeder valve first.</p> Signup and view all the answers

    How much oil should be drained from the on-load tap-changer after venting?

    <p>5-10 liters.</p> Signup and view all the answers

    What is an essential requirement regarding ventilation when working on the on-load tap-changer cover?

    <p>Adequate ventilation must be ensured.</p> Signup and view all the answers

    What is the purpose of opening the stop valve during maintenance on the on-load tap-changer?

    <p>To facilitate oil movement into another compartment.</p> Signup and view all the answers

    Why is it important to drain the area below the on-load tap-changer to be oil-free?

    <p>To ensure safe working conditions.</p> Signup and view all the answers

    What is the function of the valve of the moisture filter in the oil filter unit?

    <p>To regulate the flow of moisture into the oil filter unit</p> Signup and view all the answers

    Which valves must be closed to facilitate the setting for 'Filter particles' function?

    <p>All drain valves</p> Signup and view all the answers

    In which condition is the valve represented in red on the piping diagram?

    <p>Closed condition</p> Signup and view all the answers

    What is the role of the air-vent valve of the particle filter?

    <p>To allow air to escape during oil filling processes</p> Signup and view all the answers

    Which component directly works with the inlet valve of the unit as per the pipe diagram?

    <p>Outlet valve of the unit</p> Signup and view all the answers

    What must be done to the outlet valve when preparing for the 'Filter particles' function?

    <p>It should be fully opened</p> Signup and view all the answers

    How is oil flow indicated in the bypass function?

    <p>Using a yellow line</p> Signup and view all the answers

    Which component prevents the release of oil into the environment when closed?

    <p>Drain valve of the unit</p> Signup and view all the answers

    What is the replacement interval for VACUTAP® VRS oil compartment contacts?

    <p>1,200,000 operations</p> Signup and view all the answers

    Which of the following products requires oil compartment contact replacement only during selector maintenance?

    <p>VACUTAP® VMS®</p> Signup and view all the answers

    The oil compartment contact replacement for VACUTAP® VRF I has what operation limit?

    <p>300,000 operations</p> Signup and view all the answers

    What is the correct mixing ratio for lacquer and hardener during the application process?

    <p>50:50</p> Signup and view all the answers

    Which cleaning agent should be used to clean the polished area before lacquering?

    <p>Alcohol or spiritus</p> Signup and view all the answers

    What must happen when replacing vacuum interrupters in connection with the diverter switch insert?

    <p>The oil compartment contact must necessarily be replaced</p> Signup and view all the answers

    For what type of VACUTAP® is a replacement interval of 600,000 operations specified for oil compartment contacts?

    <p>VACUTAP® VRL I 1801-2401</p> Signup and view all the answers

    What method can be used to accelerate the drying of lacquer inside the pores?

    <p>Using a hair dryer</p> Signup and view all the answers

    What should be done to the transition areas between the damaged and undamaged material?

    <p>Round them as much as possible</p> Signup and view all the answers

    Which type of on-load tap-changer has the highest operation limit for the oil compartment contact replacement interval?

    <p>VACUTAP® VM®</p> Signup and view all the answers

    What potential risk should be avoided when using a hair dryer on lacquered surfaces?

    <p>Burning the lacquer</p> Signup and view all the answers

    For VACUTAP® VRF I 1801, what is the specified replacement interval for oil compartment contacts?

    <p>300,000 operations</p> Signup and view all the answers

    What is the common replacement interval for all types of OILTAP® mentioned?

    <p>800,000 operations</p> Signup and view all the answers

    What is the primary requirement for dielectric testing of insulating materials before operation?

    <p>Drying and dielectric testing by CTTV</p> Signup and view all the answers

    Which VACUTAP® model must have its oil compartment contacts replaced under specific operation conditions?

    <p>VACUTAP® VMS®</p> Signup and view all the answers

    To achieve a smoother surface during the lacquer application process, how often must the procedure be repeated?

    <p>Multiple times as needed</p> Signup and view all the answers

    What is the essential consideration when dealing with insulating parts in operation without prior testing?

    <p>They must be dried and tested by CTTV.</p> Signup and view all the answers

    What is the correct procedure for sampling oil when using a diverter switch insert?

    <p>Rinse the sample bottle with the oil being tested before taking the sample.</p> Signup and view all the answers

    At what temperature range should the dielectric strength tests be conducted for oil testing?

    <p>20 °C ± 5 °C</p> Signup and view all the answers

    What should be done if the test vessel of the oil testing equipment is notably colder than ambient temperature?

    <p>Warm the test vessel to ambient temperature before proceeding.</p> Signup and view all the answers

    What is the significance of checking the gap between test electrodes during oil dielectric strength testing?

    <p>To obtain consistent test results.</p> Signup and view all the answers

    What is the immediate action required after taking the oil sample?

    <p>Fill in the supplement sheet and ensure samples are not mixed up.</p> Signup and view all the answers

    Why is it important to pour out only a small amount of oil after filling the sample bottle?

    <p>To ensure the sample bottle is adequately filled (95% to 98%).</p> Signup and view all the answers

    What should be done with the rinsed oil after preparing the test vessel?

    <p>Dispose of it properly.</p> Signup and view all the answers

    What additional documentation is required when conducting a dielectric strength test on-site?

    <p>The OLTC serial number and performer’s signature.</p> Signup and view all the answers

    Study Notes

    Replacement Intervals for On-load Tap-changers

    • On-load tap-changer maintenance includes replacing diverter switch inserts, selector switch inserts, and oil compartment contacts based on operational intervals.
    • For OILTAP® M:
      • Oil compartment contacts need replacement every 2,000,000 – 2,400,000 operations.
      • Diverter switch insert replacement every 800,000 operations.
      • Full on-load tap-changer (OLTC) replacement suggested at 4,000,000 operations.
    • OILTAP® MS:
      • Replacement only necessary during selector maintenance.
      • No replacement required when retrofitting to VACUTAP® VM®.
    • Maintenance intervals for OILTAP® R and RM are at 800,000 for oil compartment and diverter switch respectively, with OLTC at 4,000,000.
    • For VACUTAP® types:
      • VACUTAP® VM®: 2,000,000 – 2,400,000 for oil compartment; 1,200,000 for diverter switch; 3,600,000 for OLTC.
      • VACUTAP® VRC, VRD, VRE, etc.: 1,200,000 for both oil compartment and diverter switch.
      • VACUTAP® VRF I: oil compartment every 300,000, diverter switch every 1,200,000, OLTC at 3,600,000.

    Selector Switch Insert Replacement

    • Selector switch insert intervals are initiated based on operational counts specific to each on-load tap-changer type.
    • ECOTAP® VPD® and VACUTAP® VVS® have no oil compartment contact replacement, yet require OLTC maintenance at 500,000 operations.
    • OILTAP® V types necessitate oil compartment replacements at 800,000 with OLTC intervals at 4,000,000.

    Maintenance and Service Labeling

    • Service labels are mandatory after maintenance performed by certified Premium Service Providers.
    • Labels must include the date of maintenance and motor-drive unit's operations counter.
    • Previous labels should not be removed; new labels should be placed below existing ones for clarity.

    Incident Report Checklist

    • Requires comprehensive details about the operator, substation, transformer data, and on-load tap-changer specifics.
    • Document the number of operations and last maintenance date.
    • Incident details must specify whether it occurred during a tap change operation and the condition of protective devices pre- and post-incident.

    General Information for Operators

    • Operators must be aware of required maintenance intervals and procedures to ensure efficient operation and safety.
    • Knowledge of device interactions and operational impacts can facilitate better maintenance planning and incident responses.### Incident Investigation
    • Clarification needed on network switching operations, substations, or environmental impacts (e.g., lightning strikes, short circuits).
    • Importance of immediate reporting on actions taken post-incident, such as mechanical tap-change operations or component replacements.

    Test Procedures and Standards

    • Oil testing carried out to assess reliability and safety, using standards like IEC and ASTM.
    • Key parameters in oil testing include:
      • Dielectric strength under IEC 156 and ASTM D877 standards.
      • Water content in ppm, indicating oil's purity and dielectric properties.

    Reporting and Documentation

    • Documentation process involves taking photographs of damaged components for record-keeping and analysis.
    • Completed incident forms should be returned to pertinent service contacts, emphasizing thorough communication.

    Oil Management in Tap-Changers

    • Instructions provided for draining oil and managing gases in on-load tap-changers.
    • Equipment distinctions:
      • Tap-changers may have dedicated pipes or valves for oil drainage, affecting maintenance steps.
      • Procedures vary based on equipment configuration, e.g., gas cushion presence.

    Safety Protocols

    • Extreme caution is emphasized due to the flammable nature of switching oil and the potential accumulation of explosive gases.
    • Adequate ventilation and avoidance of ignition sources are crucial during maintenance.
    • Specific steps outlined for safely venting gases, draining oil, and handling equipment, including waiting periods to allow gas dissipation post-draining.

    Technical Specifications

    • Oil conservators and their design must consider thermal expansion and oil displacement due to switched gases.
    • Recommendations for oil conservator contents based on insulation levels are crucial to maintain efficiency and safety.
    • In-depth understanding of oil behavior under different operational stresses is necessary for effective management and troubleshooting.

    Key Definitions

    • GIS: Gas-insulated switchgear
    • SF6: Sulfur hexafluoride
    • SiC: Silicon carbide
    • ZnO: Zinc oxide
    • OLTC: On-load tap-changer### Oil Content and Tap-Changer Specifications
    • Different tap-changer types (C I, C III, D, E, F, G, K) with distinct voltage capacities (20 kV to 220 kV) and their corresponding oil volume specifications.
    • V_gas indicates the volume of oil displaced due to switching gases.
    • V_OLTC refers to the oil content within the diverter switch oil compartment.
    • V_130°C denotes the oil volume expansion at a temperature of 130°C.
    • V_delta captures the change in oil volume inside the conservator.
    • V_min is the minimum required oil content in the conservator for safe operation.

    Mobile Oil Filter Unit OFP 010-SD Overview

    • The mobile oil filter unit is crucial for filtering insulating oil and must be checked for completeness before deployment.
    • Essential components include hoses, suction tubes, pipe adapter, and operational guides.
    • Must carry sufficient oil reserves, measuring devices for dielectric strength, empty barrels, drip pans, waste management materials, and cleaning agents.

    Preparations and On-Site Procedures

    • Ensure environmental safety by using plastic tarps and drip pans to contain any oil leakage.
    • Inspect the mobile oil filter unit for leaks and functionality prior to operation.
    • Establish correct hose connections to maintain proper oil flow direction.

    Valve Settings for Oil Filtration

    • Manual valve operations are needed for different functions including "Bypass", "Filter particles", "Filter particles and moisture", and "Drain oil filter unit".
    • Each process requires specific valve configurations to redirect oil flow effectively through appropriate filters.

    Handling of Filter Cartridges

    • New filters must be installed before starting the filtering process; Fuller's earth should be used in specified bags for particle filtration.
    • Fine particle and moisture filters must be changed based on pressure thresholds or water absorption metrics, ensuring oil purity is maintained.
    • Care must be taken to avoid humidity exposure during filter storage, and used filters should be packed securely due to the presence of insulating oil residues.

    Coarse Filter Maintenance

    • The coarse filter requires routine cleaning before each filtering process, when flow rates drop significantly, or before unit removal. Regular maintenance is crucial for optimal performance and oil quality retention.

    On-Load Tap-Changers Replacement Intervals

    • Replacement of oil compartment contacts not required when retrofitting to VACUTAP® VM® is not possible.
    • OILTAP® models (R, RM, G) require oil compartment contacts replacement after 800,000 to 4,000,000 operations.
    • VACUTAP® VM® has a replacement interval of 2,000,000 to 2,400,000 operations for oil contacts; 3,600,000 for diverter switch insert.
    • VACUTAP® VMS® only replaced during selector maintenance; has 600,000 replacement interval for oil contacts.
    • Other VACUTAP® models (VRC, VRD, VRE, VRF, VRG) have intervals of 1,200,000 operations for oil contacts and 3,600,000 for diverter switch insert.

    Maintenance and Safety Procedures

    • Checking contact wear necessary for VACUTAP® VRS, VRM, VRL®, VRH®, and VRX® models, with a 1,200,000 operational interval.
    • Replacement intervals for VACUTAP® VRL I vary based on network and furnace operations, ranging from 300,000 to 600,000 for oil contacts.
    • Ensure all auxiliary circuits de-energized before working on on-load tap-changer cover.
    • Avoid electrical devices that may cause spark formation during maintenance.
    • Must open stop valve and bleeder valve to vent switching gas before opening the tap-changer cover.

    Oil Maintenance and Testing Procedures

    • For oil sampling, rinse sample bottles and avoid current flow while filling; must be at least 95% filled.
    • The dielectric strength of oil tested on-site; use appropriate equipment and follow temperature standards.
    • Clean testing equipment thoroughly before use to avoid contamination.
    • Insulating materials must be dielectrically tested before commissioning if not already done.
    • Cleaning and lacquer application procedure for damaged surfaces includes polishing, cleaning with alcohol, and careful maintenance to ensure effectiveness.

    Diagrammatic Reference for Operations

    • Pipeline diagrams indicate closed and opened conditions for valves related to filtering and draining oil.
    • Clear labeling on valves ensures proper management of oil flow, draining, and filtering systems.

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    Explore the key replacement intervals for diverter switch inserts, selector switch inserts, and oil compartment contacts. This quiz covers essential concepts related to maintenance schedules and practices for on-load tap-changers. Perfect for technicians and engineers in the electrical field.

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