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Transformer OLTC Positioning Guide
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Transformer OLTC Positioning Guide

Created by
@BestSellingBeige

Questions and Answers

What should be done to position the OLTC insert correctly?

  • Ensure the suction pipe is disconnected while positioning.
  • Align the stationary change-over selector contacts horizontally.
  • Secure the OLTC insert to prevent any movement.
  • Move the hanging OLTC insert so switching elements can pass. (correct)

    • What is the purpose of the operating key during the adjustment process?

  • To securely fasten the suction pipe.
  • To set the OLTC insert to the adjustment position. (correct)
  • To detach the OLTC insert from the oil compartment.
  • To calibrate the gear mechanism support plate.

    • Which step is crucial before reinstalling the gear mechanism?

  • Setting the gear mechanism to the adjustment position. (correct)
  • Ensuring the lock tabs are fastened tightly.
  • Securing the suction pipe fitting completely.
  • Filling the oil compartment with transformer oil.

    • What must be done with the screws when attaching the gear mechanism supporting plate?

    <p>Apply a maximum torque of 14 Nm and secure them with lock tabs.</p> Signup and view all the answers

    What is the final step after filling the oil compartment?

    <p>Closing the cover of the tap changer head.</p> Signup and view all the answers

    What is the role of the change-over selector in the adjustment process?

    <p>To operate the movable contacts in the adjustment procedure.</p> Signup and view all the answers

    What type of oil should be used for filling the oil compartment?

    <p>Transformer oil.</p> Signup and view all the answers

    What should be done after adjusting the position of the gear mechanism?

    <p>Insert the energy accumulator fixing bolt.</p> Signup and view all the answers

    What should be done if the O-ring gasket is found to be in poor condition?

    <p>Replace it with a new gasket.</p> Signup and view all the answers

    What is the maximum torque specified for the attachment of the head cover bolts?

    <p>35 Nm</p> Signup and view all the answers

    What should be checked before returning the transformer to service?

    <p>If the tap changer and transformer are undamaged.</p> Signup and view all the answers

    What is the maximum torque that should be applied to the screw cap M16/w.s. 22?

    <p>2 Nm</p> Signup and view all the answers

    Which component is referenced for checking the electrical and mechanical end position of the motor drive unit?

    <p>Operating Instructions No. 40.</p> Signup and view all the answers

    What action should be taken if the protective relay responds during the operational test?

    <p>Contact an authorized MR representative.</p> Signup and view all the answers

    When preparing to bleed the tap changer head, what initial step is required?

    <p>Remove screw cap M30 with wrench size 36.</p> Signup and view all the answers

    What is necessary to ensure when operating the stop valve between the oil conservator tank and tap changer head?

    <p>It needs to be inspected for leaks.</p> Signup and view all the answers

    Which step must be taken before operating and bleeding the stationary oil filter unit?

    <p>Ensure that the transformer is de-energized.</p> Signup and view all the answers

    What is the primary function of the protective relay mentioned in the content?

    <p>To prevent energizing the transformer during testing.</p> Signup and view all the answers

    In what situation should the tap changer not be reconnected?

    <p>If it has not been checked beforehand.</p> Signup and view all the answers

    In case of an operational test, how should the ground connections be handled?

    <p>They must remain intact during the test.</p> Signup and view all the answers

    What is the function of the spring washers mentioned in the attachment of the head cover?

    <p>To maintain tension and avoid loosening.</p> Signup and view all the answers

    What should be checked as part of the operational test of the protective relay?

    <p>The proper function of circuit breakers.</p> Signup and view all the answers

    What should be done if serious trouble with the tap changer or motor drive occurs?

    <p>Immediate switching off by circuit breakers is recommended.</p> Signup and view all the answers

    What is NOT a prerequisite for testing the protective relay according to the provided guidelines?

    <p>Ensuring ground connections are removable.</p> Signup and view all the answers

    What is the primary purpose of the tap change indication wheel?

    <p>To show the precise alignment between motor drive and tap changer</p> Signup and view all the answers

    How many sections are there on the tap change indication wheel in case of MA 8 motor drive?

    <p>30 sections</p> Signup and view all the answers

    What should be ensured during the adjustment of symmetrical coupling?

    <p>Both readouts of the motor drive and tap changer are equal</p> Signup and view all the answers

    What is the consequence of minor asymmetry in the tap change operation?

    <p>It is acceptable within specified limits</p> Signup and view all the answers

    From which point is the section count measured during the tap change operation?

    <p>From the start of the tap change operation</p> Signup and view all the answers

    What is indicated by the red center mark on the tap change indication wheel?

    <p>The starting reference for section counting</p> Signup and view all the answers

    What does the 'diverter switch' refer to in the provided content?

    <p>An indication of tap change without impact on performance</p> Signup and view all the answers

    In the context of the tap change operation, what does each section of the indication wheel represent?

    <p>One complete rotation of the crank</p> Signup and view all the answers

    Which type of wrench is correctly matched with its corresponding DIN and wrench size?

    <p>Double-ended open jaw wrench – DIN A | 895 – 22x24</p> Signup and view all the answers

    What is the DIN designation for the double-ended socket wrench listed?

    <p>B | 896</p> Signup and view all the answers

    Which size corresponds with the hexagon socket screw key

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

    Which wrench type uses a double-ended configuration?

    <p>Double-ended open-jaw wrench</p> Signup and view all the answers

    How many types of wrench are listed under DIN designation A | 895?

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

    What is the purpose of the tools listed in the context?

    <p>For installation and inspection of bolts &amp; nuts</p> Signup and view all the answers

    What does the size designation '17x19' refer to?

    <p>A size of wrench</p> Signup and view all the answers

    Which operating key fits with the withdrawal and reinstallation of the OLTC insert?

    <p>Operating key B | 896</p> Signup and view all the answers

    The OLTC insert should be cleaned only after it has been removed from the gear mechanism.

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

    The inspection intervals for the OLTC insert are determined by the age of the equipment.

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

    Contact wear can be evaluated by measuring the transition resistors.

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

    It is safe to operate the OLTC without verifying the sealing condition of the suction pipe.

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

    The main function of cleaning the oil compartment is to enhance lubrication for the gear mechanism.

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

    Replacing the contact rollers is not necessary during regular maintenance of the OLTC insert.

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

    The OLTC insert can be reinstalled without reinserting the suction pipe first.

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

    The change-over selector is switched off during the withdrawal of the OLTC insert.

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

    The OLTC insert should be exposed to air for no more than 12 hours.

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

    An oil pump is necessary for the ease of oil change procedures.

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

    The determination of contact wear takes place with the change-over selector.

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

    Miscellaneous brushes and rags are not essential for cleaning during the inspection.

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

    The maximum oil filling quantity for the OLTC insert is 320 litres.

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

    Cleaning the oil compartment does not require specific brushes.

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

    Tools required for cleaning include only standard brushes.

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

    Care and cleanliness are secondary priorities during the inspection process.

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

    Water content of oil in on-load tap changers is required to be measured by the Karl Fischer method.

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

    The normal interval for inspecting a transformer with an oil filter is recommended to be every 5 to 6 years.

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

    IEC Publication 422 provides standards related to the dielectric strength of oil under test conditions.

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

    The recommended maximum dielectric strength for tap changer oil is 35 kV/2.5 mm.

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

    DIN 57 370 Teil 1 is cited for guidelines on measuring the temperature of the oil during sample-taking.

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

    The number of tap change operations does not influence the recommended inspection intervals.

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

    It is suggested that inspections of tap changing equipment be conducted by untrained personnel.

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

    An inspection report must be submitted to ensure proper future recommendations.

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

    The OLTC insert is one of the basic parts of the OLTC.

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

    The change-over selector is available in all OLTC types.

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

    The oil compartment is not subject to inspection during maintenance of the OLTC.

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

    The tap changer head is one of the basic parts marked for inspection.

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

    The OLTC can operate without the separate change-over selector.

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

    The basic parts of the OLTC are represented in black and white in the inspection guide.

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

    The model H Ill 400A—145 is available without a change-over selector.

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

    The delivery date for the modified components is noted as 6/89.

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

    H I 400 A—123 with a built-in component is marked as 'no. 2' with a value of 3.6.

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

    The configuration H II 400A—40/76 is listed as having a built-in feature, and it records a value of 10.6.

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

    There are two types of configurations mentioned for H Ill 400A—123 one with and one without a built-in feature.

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

    All models listed with built-in features have been designated with the same value of 36/71.

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

    The term 'separatly attached' is used within the context of the H I 400A—145 configuration.

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

    The H I 400Y model is depicted without any specific features marked.

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

    The document details a total of five distinct configurations for the H 111 models.

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

    The phrase 'without change-over selector' appears only for the model H 111 400 A.

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

    Study Notes

    OLTC Installation and Adjustment

    • Position the hanging OLTC insert correctly for smooth switching between stationary change-over selector contacts.
    • OLTCs can either have a built-in change-over selector or a separately attached one, impacting the positioning during installation.

    Adjustment Position Setup

    • OLTC insert must be set to the adjustment position using the operating key.
    • For units with a built-in selector, move the change-over contacts counterclockwise to reach the switched position.
    • Detach the operating key to reinsert the suction pipe and center the OLTC insert in the oil compartment.

    Gear Mechanism Installation

    • Reinstall the gear mechanism in the reverse order of its removal.
    • Gear mechanism needs to be set to the adjustment position using the position indicator and red gear marks.
    • Securely attach the gear mechanism supporting plate with five M8 x 30 screws at a maximum torque of 14 Nm, using lock tabs for security.

    Oil Filling Procedure

    • Fill the oil compartment with new transformer oil to the gear mechanism support plate level.
    • Ensure O-ring gasket is intact, replace if necessary before covering the tap changer head.
    • Attach the head cover with 24 M10 x 35 bolts, maintaining a maximum torque of 35 Nm and securing with spring washers.

    Bleeding and Safety Checks

    • Open stop valve between oil conservator tank and tap changer head for proper oil flow.
    • Bleed the tap changer head and suction pipe to eliminate air pockets before operation.
    • Ensure that the transformer and connections are undamaged and cannot be energized during testing.

    Drive Shaft Assembly

    • Couple horizontal drive shaft to the tap change indication wheel for synchronization.
    • The MA 8 motor drive's indication wheel is divided into 30 sections, each correlating to a full rotation.
    • Ensure that position indications of motor drive and tap changer are equal for symmetrical coupling during adjustment.

    Miscellaneous Checks

    • Conduct a test on the protective relay, ensuring that all circuit breakers function correctly.
    • Equipment must be safe to energize post-checks, and fire-extinguishing systems must be operational before the relay checks.
    • Contact authorized service representatives for serious tap changer or motor drive issues that cannot be repaired on-site.

    Functional Principle of OLTC

    • On-load tap changers (OLTC) are vital components in transformers, allowing adjustments to voltage levels while the transformer is energized.
    • OLTC aids in maintaining efficient operation and reliability of electrical systems.

    Designation of OLTC Models

    • OLTC models are designated according to their specifications, including current ratings and voltage capacities.
    • Common models include H I 400 Y, H I I 400 A, H I I 400 A-123, and H I I 400 A-145.

    Principal Parts of the OLTC

    • Essential components include:
      • Tap changer head
      • Oil compartment
      • OLTC insert
      • Change-over selector (specific to certain models)

    Inspection Intervals

    • Regular inspections recommended every 6 to 7 years or after a specified number of operation cycles to ensure functionality.
    • Key checks include dielectric strength and water content of oil, adhering to standards like IEC Publication 422 and DIN 57 370.

    Summary of Inspection Works

    • Inspections involve:
      • Removal and reinstallation of the OLTC insert
      • Cleaning of the oil compartment and OLTC components
      • Oil change and checking for contact wear and transition resistors

    Preparations for Inspection

    • Equipment needed includes:
      • Empty vessels for dirty oil disposal
      • Clean oil for refilling
      • Oil pump for easy oil change
      • Cleaning brushes and rags
    • Work should maintain strict cleanliness to avoid contamination.

    Removing the OLTC Insert

    • Steps for removal include:
      • Taking off the tap changer head cover
      • Detaching the gear mechanism
      • Withdrawing the suction pipe
      • Turning off the change-over selector and operational key

    Cleaning Procedures

    • Cleaning focuses on:
      • Oil compartment and OLTC insert
      • Suction pipe to ensure proper flow and functionality

    Inspection of the OLTC Insert

    • Inspections include:
      • Measuring transition resistors for integrity
      • Assessing contact wear for operational efficiency

    Replacing the Contact Rollers

    • Replacement entails:
      • Removing old contact rollers
      • Installing new rollers to maintain voltage regulation effectiveness

    Reinstalling the OLTC Insert

    • Reinstallation involves:
      • Carefully reinserting the OLTC insert and suction pipe
      • Reinstalling the gear mechanism to re-establish connectivity

    Oil Filling

    • Oil filling quantities vary by model, ensuring the correct amount is used for optimal performance.
    • Essential parameters include rated voltage levels, current specifications, and recommended oil quality standards.

    Key Inspection Data

    • Regular monitoring is critical:
      • The oil's dielectric strength and water content should be less than 40 ppm and above 30 kV/2.5 mm for reliability.
    • Inspections are performed in accordance with established standards and documented to ensure safety and compliance.

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    Description

    This quiz focuses on the operational positioning of On-Load Tap Changers (OLTC) in transformers, specifically regarding built-in and separately attached change-over selectors. It provides insights on ensuring smooth functionality of switching elements with stationary change-over selector contacts. Test your understanding of OLTC mechanisms and their alignment procedures.

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