On-load Tap Changer Type A_Operating Instructions
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Questions and Answers

What is the maximum rated transformer current for the A III 100 Y tap changer?

  • Up to 50 A (correct)
  • 100 A
  • Over 100 A
  • 50 A

    • How many tap change operations is the A I 100 tap changer rated for?

  • 70,000 operations
  • 100,000 operations
  • 10,000 operations (correct)
  • 50,000 operations

    • After how many years should inspections be conducted regardless of the number of tap change operations for certain models?

  • 5-6 years (correct)
  • 10,000 operations
  • 1 year
  • 2 years

    • Which drilling template corresponds to models with a change-over selector?

    <p>053 907</p> Signup and view all the answers

    What is the name of the motor drive unit with dimension drawing N 1267?

    <p>MA 7</p> Signup and view all the answers

    What is the maximum recommended weight for the motor drive MA 9?

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

    Which component should be positioned using a drilling template?

    <p>Tap changer head</p> Signup and view all the answers

    What is the purpose of the oil proof gasket during the installation of the tap changer?

    <p>To provide a seal against oil leakage</p> Signup and view all the answers

    During the connection of the tapped winding, what is crucial to ensure?

    <p>Leads can be connected without force</p> Signup and view all the answers

    What should be done before drying the transformer?

    <p>A ratio test at low a.c. voltage</p> Signup and view all the answers

    What is the diameter of the coupling bolt used with the drive shaft?

    <p>12 mm</p> Signup and view all the answers

    What is the consequence of overrunning the end position indicated on the connection diagram?

    <p>Potential damage to the tap changer</p> Signup and view all the answers

    What is the maximum length recommended for the M12 studs during installation?

    <p>45 mm</p> Signup and view all the answers

    What is the required position for the protective relay when installed?

    <p>Horizontal with the arrow pointing to the oil conservator</p> Signup and view all the answers

    What must be noted about the motor drive unit and tap changer before installation?

    <p>Their serial numbers must coincide</p> Signup and view all the answers

    What is the minimum incline required for the pipe line connecting the protective relay to the oil conservator?

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

    Which component should be installed between the protective relay and the oil conservator?

    <p>A stop cock</p> Signup and view all the answers

    How should the bevel gear be attached to the transformer cover?

    <p>By means of 2 bolts through 18 mm diameter holes</p> Signup and view all the answers

    What design feature allows the bevel gear to function properly?

    <p>Diverts driving force from vertical to horizontal direction</p> Signup and view all the answers

    What is a critical consideration when mounting the motor drive unit?

    <p>It should be mounted in a position recommended by the connection diagram</p> Signup and view all the answers

    Where is the drive shaft located in the assembly process?

    <p>Between the motor drive unit and the bevel gear, and then to the tap changer head</p> Signup and view all the answers

    What is the primary function of the tap changer type A?

    <p>To act as a selector switch for voltage control</p> Signup and view all the answers

    What should be checked against the shipping documents upon receipt of the tap changer?

    <p>The completeness of shipment</p> Signup and view all the answers

    What is the maximum number of operating positions for a tap changer model with a change-over selector?

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

    What is a necessary step before the installation of the tap changer?

    <p>Storing it in a dry place</p> Signup and view all the answers

    Which models of tap changers does the instruction apply to?

    <p>All models including three-pole and single-pole tap changers</p> Signup and view all the answers

    What distinguishes the tap changer type A's switching principle?

    <p>It combines features of both a diverter switch and a tap selector</p> Signup and view all the answers

    Where is the tap changer fastened to the transformer?

    <p>At the transformer cover</p> Signup and view all the answers

    Why should the tap changer be unpacked immediately before installation?

    <p>To prevent moisture damage</p> Signup and view all the answers

    What is the maximum temperature allowed during the vacuum drying process of the tap changer?

    <p>110°C</p> Signup and view all the answers

    What should be done to reduce the number of tap change operations before the tap changer is filled with oil?

    <p>Minimize tap change operations</p> Signup and view all the answers

    During the drying process, what must be done before applying the vapor-phase drying?

    <p>Open the kerosene drain plug</p> Signup and view all the answers

    What is the required final temperature for the heating phase in the vapor-phase drying process?

    <p>125°C</p> Signup and view all the answers

    How long is the maximum duration for vacuum drying at a reduced pressure?

    <p>100 hours</p> Signup and view all the answers

    What is the torque specification for tightening the cover screws of the tap changer?

    <p>34 Nm</p> Signup and view all the answers

    What is essential to do after completing the tap changer test according to the provided instructions?

    <p>Run the tap changer into adjustment position</p> Signup and view all the answers

    What should NEVER be done after the drying process is completed?

    <p>Operate the tap changer without oil</p> Signup and view all the answers

    What must coincide with the serial number of the protective relay during installation?

    <p>The tap changer</p> Signup and view all the answers

    What is the minimum required incline for the pipeline connecting the protective relay to the oil conservator?

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

    In which position should the protective relay be installed?

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

    What component should be installed between the protective relay and the oil conservator?

    <p>A stop cock</p> Signup and view all the answers

    Which operating position is required for both the motor drive unit and the tap changer?

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

    How should the bevel gear be attached to the transformer cover?

    <p>Using 2 bolts</p> Signup and view all the answers

    What is critical for the drive shaft in relation to the motor drive unit and tap changer head?

    <p>It should be assembled according to specific instructions</p> Signup and view all the answers

    What should be done to prevent excessive vibrations during the installation of the motor drive unit?

    <p>Use vibration dampeners</p> Signup and view all the answers

    What is the maximum temperature to maintain during the vacuum drying process for a tap changer?

    <p>110°C</p> Signup and view all the answers

    What is the minimum drying duration in vacuum for the tap changer?

    <p>100 hours</p> Signup and view all the answers

    What should be done with the kerosene drain plug before applying vapor-phase drying?

    <p>It must be removed.</p> Signup and view all the answers

    What is a critical action to take after completing the tap changer test?

    <p>Run the tap changer into the adjustment position.</p> Signup and view all the answers

    What is the maximum torque specification for tightening the cover screws of the tap changer?

    <p>34 Nm</p> Signup and view all the answers

    What is the required maximum final temperature for the kerosene vapor during the drying process?

    <p>125°C</p> Signup and view all the answers

    What must be done to the tap changer before it operates post-drying?

    <p>It must be filled with oil.</p> Signup and view all the answers

    During the predrying phase, what is the maximum temperature applied to the tap changer?

    <p>110°C</p> Signup and view all the answers

    What is the recommended method for securing the tap changer to the transformer cover?

    <p>Using a mounting flange with bolts</p> Signup and view all the answers

    What should be done to ensure proper connection of the tap leads to the tap changer?

    <p>All connections should be locked safely and made without force.</p> Signup and view all the answers

    What is a critical action to take prior to drying the transformer?

    <p>Perform a ratio test at a low a.c. voltage.</p> Signup and view all the answers

    What precaution must be taken when lifting the tap changer over the transformer cover?

    <p>Take care not to damage the connecting contacts.</p> Signup and view all the answers

    What items must be supplied with the tap changer for correct installation?

    <p>A connection diagram for the tap changer.</p> Signup and view all the answers

    During the installation, what type of gasket is recommended for sealing the tap changer head?

    <p>An oil-proof gasket</p> Signup and view all the answers

    What must be avoided when assembling the leads to the tap changer?

    <p>Leads must not be connected using excessive force.</p> Signup and view all the answers

    What is a significant risk of overrunning the end position during the tap changer operation?

    <p>It could cause the tap changer to rotate incorrectly.</p> Signup and view all the answers

    What is the purpose of aligning the trunnions before connecting the drive shaft?

    <p>To facilitate proper mechanical connection between components.</p> Signup and view all the answers

    What must be done regarding the coupling brackets before mounting the drive shaft?

    <p>They need to be cut to the required size if supplied oversize.</p> Signup and view all the answers

    Why is it important to check the mechanical operation of the tap changer before voltage application?

    <p>To avoid potential mechanical breakdown during operation.</p> Signup and view all the answers

    What is the correct action to take after filling the tap changer with transformer oil?

    <p>Bleed the tap changer head via the bleeder screw.</p> Signup and view all the answers

    What is the function of the ground screw in the tap changer assembly?

    <p>To prevent electrical leakage to the transformer cover.</p> Signup and view all the answers

    What should be done before transporting the transformer without the motor drive unit?

    <p>Set the motor drive to the adjustment position and uncouple it.</p> Signup and view all the answers

    What is the maximum torque specification for the ground screw of the tap changer head?

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

    Which of the following actions is NOT necessary before starting the transformer acceptance test?

    <p>Paint the coupling brackets with decorative paint.</p> Signup and view all the answers

    What is the recommended method for testing transformer insulating oil?

    <p>Karl Fischer method</p> Signup and view all the answers

    Which of the following components is best checked for dimension drawing N 1255?

    <p>Motor drive unit MA 9</p> Signup and view all the answers

    What is the purpose of having inspections conducted by the Technical Service Department?

    <p>To ensure expert execution and retrofitting of components</p> Signup and view all the answers

    What is the dielectric strength standard for the A I 100 tap changer according to the provided standards?

    <blockquote> <p>40 kV/2.5 mm</p> </blockquote> Signup and view all the answers

    What must the water content in oil for the A III 100 Y tap changer not exceed?

    <p>&lt; 40 ppm</p> Signup and view all the answers

    What action should be taken if the inspection is not performed by MR personnel?

    <p>Send the inspection report for files</p> Signup and view all the answers

    Which parameter is crucial to monitor when testing transformer insulating oil?

    <p>Dielectric strength</p> Signup and view all the answers

    What should be included when requesting necessary spare parts for an inspection?

    <p>Tap changer number and number of operations</p> Signup and view all the answers

    What is the primary function of the tap changer type A?

    <p>To vary the voltage levels in a transformer</p> Signup and view all the answers

    What distinguishes the tap changer type A's switching principle?

    <p>It combines features of a diverter switch and a tap selector.</p> Signup and view all the answers

    For tap changers equipped with a change-over selector, what is the maximum number of operating positions they can have?

    <p>15 operating positions</p> Signup and view all the answers

    What should be done with the tap changer components prior to installation?

    <p>Keep them in their shipping plastic cover until installation.</p> Signup and view all the answers

    What is a necessary action before the drying process of the transformer?

    <p>Verify the tap changer is in its adjustment position.</p> Signup and view all the answers

    What must be checked against the shipping documents upon receipt of the tap changer?

    <p>The quantity and completeness of the parts</p> Signup and view all the answers

    What is crucial to ensure while connecting the tapped winding?

    <p>Follow the specific color codes of the wires.</p> Signup and view all the answers

    What is a critical consideration when mounting the motor drive unit?

    <p>Check that its connection to the drive shaft is secure.</p> Signup and view all the answers

    What is the purpose of the mounting flange during the installation of the tap changer head?

    <p>To securely attach the tap changer to the transformer</p> Signup and view all the answers

    What is a critical precaution to take while connecting the tapped winding to the tap changer?

    <p>Avoid any contact with live parts</p> Signup and view all the answers

    During the transformer ratio test, what is necessary for operating the drive shaft of the tap changer head?

    <p>A hand wheel or hand crank</p> Signup and view all the answers

    What must be ensured regarding the clearance when leads cross the oil compartment surface?

    <p>An adequate clearance to the surface and live parts</p> Signup and view all the answers

    What is the recommended method for aligning the studs during the installation of a tap changer?

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

    Which step must be taken before drying the transformer?

    <p>Conduct a ratio test at low a.c. voltage</p> Signup and view all the answers

    What is essential to avoid when fastening the tap changer head to the mounting flange?

    <p>Damaging the connecting contacts</p> Signup and view all the answers

    What is a potential risk of overrunning the end position indicated on the connection diagram during operation?

    <p>There may be a risk of mechanical failure</p> Signup and view all the answers

    Which precaution must be taken when mounting the motor drive unit?

    <p>It must be protected against excessive vibrations.</p> Signup and view all the answers

    What must be ensured regarding the serial numbers during installation?

    <p>The serial number of the motor drive unit and tap changer must be the same.</p> Signup and view all the answers

    What is a necessary feature for the bevel gear's installation?

    <p>It should be attached with exactly two bolts.</p> Signup and view all the answers

    Which orientation should the protective relay be installed in?

    <p>In a horizontal position with the arrow pointing to the oil conservator.</p> Signup and view all the answers

    What is the minimum incline required for the pipeline to the oil conservator?

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

    What component should be included between the protective relay and the oil conservator?

    <p>A stop cock.</p> Signup and view all the answers

    What is the role of the drive shaft in the assembly?

    <p>To connect the motor drive to the tap changer head.</p> Signup and view all the answers

    Why must the protective relay's serial number match that of the tap changer?

    <p>To guarantee correct operation.</p> Signup and view all the answers

    What should be done before returning the transformer to service after an inspection?

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

    What is the purpose of the protective relay within the tripping circuit of the circuit breakers?

    <p>To switch off the transformer immediately upon energization.</p> Signup and view all the answers

    Which of the following components requires occasional inspections for proper operation?

    <p>The motor drive unit, protective relay, and tap changer head.</p> Signup and view all the answers

    What must be checked to ensure safe operation of the tap changer and transformer during testing?

    <p>Stop valves between the oil conservator and tap changer head are open.</p> Signup and view all the answers

    In case of a response from the protective relay, what immediate action is required?

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

    What is a critical element to ensure about the motor drive's electrical space heater?

    <p>It operates within specified temperature ranges.</p> Signup and view all the answers

    During prolonged standby periods, what should be done with the motor drive unit’s heater?

    <p>Connect to power to maintain temperature.</p> Signup and view all the answers

    What should occur immediately after operational tests are performed on tap changers?

    <p>Check the function of the protective relay.</p> Signup and view all the answers

    What must be ensured when connecting the drive shaft to the implements?

    <p>The trunnions are properly aligned.</p> Signup and view all the answers

    What material are the coupling brackets and square shaft made from?

    <p>Corrosion-proof steel.</p> Signup and view all the answers

    What should be done to equalize the rotation lag between the tap changer and motor drive?

    <p>Adjust according to specific operating instructions.</p> Signup and view all the answers

    How should the tap changer be filled with oil?

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

    What is the maximum torque specification for the ground screw of the tap changer head?

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

    Before applying voltage, what should be checked regarding the tap changer and motor drive?

    <p>The mechanical operations of both components.</p> Signup and view all the answers

    What is required before the transformer can be transported without the motor drive unit?

    <p>Set the motor drive to the alignment position.</p> Signup and view all the answers

    What critical step must be taken during the oil filling process of the tap changer?

    <p>Bleed the tap changer head via the bleeder screw.</p> Signup and view all the answers

    A mounting flange is not recommended for mounting the tap changer head on the transformer cover.

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

    The tap leads can be connected to the tap changer without any specific connection diagram.

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

    An oil proof gasket should be placed on the mounting flange before lowering the tap changer.

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

    Every revolution of the drive shaft requires more than one step to operate the tap changer head.

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

    The maximum weight of the motor drive MA 7 is approximately 60 kg.

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

    The drive shaft can cross the oil compartment surface without any clearance requirements.

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

    Cleaning the sealing surfaces is an important initial step before attaching the tap changer.

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

    The coupling parts and bevel gear have a maximum weight of approximately 20 kg.

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

    The tap changer type A can support up to 15 operating positions if it has a change-over selector.

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

    The tap changer must be unpacked immediately after its shipment to be stored properly.

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

    The tap changer type A is primarily a transformer for star-connection.

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

    Before installing, the tap changer components should be stored in a dry place to prevent moisture damage.

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

    The drive shaft and bevel gear are required components for the operation of the tap changer.

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

    The protective relay must be installed below the oil conservator during the assembly process.

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

    Models of tap changers without a change-over selector are not available for more than 8 operating positions.

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

    The tap changer oil compartment is isolated from the transformer oil to maintain operational integrity.

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

    The tap changer must be operated without oil after the drying process is completed.

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

    The maximum temperature for vacuum drying applied to the tap changer is 110°C.

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

    For the vapor-phase drying process, the kerosene vapor temperature should not exceed 125°C.

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

    The tap changer should be subjected to a minimum drying process to obtain guaranteed dielectrical values.

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

    Before performing the drying process, the kerosene drain plug must be opened.

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

    The tap changer head cover has 10 screws that need to be uniformly tightened.

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

    The drying duration for vacuum drying at a reduced pressure can last up to 100 hours.

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

    After filling the tap changer with oil, it is crucial to keep the draining plug open.

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

    The interior of the tap changer should be protected using oxygen-sealing methods.

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

    Inspection of the tap changer head and motor drive unit is necessary only occasionally.

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

    The protective relay must be connected to the power supply after the transformer is put into service.

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

    It is important for the circuit breakers to be able to switch on the transformer only after the protective relay has been activated.

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

    The tap changer and transformer can be reconnected without prior checking.

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

    The motor drive unit should have a properly functioning electrical space heater.

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

    All stop valves between the oil conservator and tap changer head should be closed during inspection.

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

    Serious trouble with the tap changer or motor drive should be addressed immediately by contacting the transformer manufacturer.

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

    Regular inspections of tap changing equipment can be performed in less than a day if well prepared.

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

    Inspection of transformer insulating oil does not require any specific standards.

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

    Water content standards for oil testing recommend a maximum of 40 ppm for the A III 100 Y tap changer.

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

    The inspections should always be conducted by MR personnel to ensure reliability.

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

    The dielectric strength for the A I 100 tap changer is less than 40 kV/2.5 mm.

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

    Certain vintage tap changers may have components that require retrofitting during inspections.

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

    It is unnecessary to record oil temperature during sample-taking for transformer oil testing.

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

    The recommended maximum water content for oil testing for the A III 100 Δ tap changer is 30 ppm.

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

    Study Notes

    On-load Tap Changer Type A

    • The tap changer type A is a combination of a diverter switch and a tap selector.
    • The tap changer is separated from the transformer oil by an oil compartment cylinder.
    • The tap changer models without a change-over selector offer up to 8 operating positions.
    • Tap changer models with a change-over selector offer up to 15 operating positions.

    Shipment & Installation

    • The tap changer is shipped with a maximum weight of 55 kg.
    • The tap changer should be stored in a dry place until installation and unpacked immediately before installation.
    • The tap changer must be installed on a mounting flange soldered to the transformer cover.
    • Use a drilling template for positioning the mounting studs.

    Connecting the Tapped Winding & Take-Off Lead

    • All lead connections to the tap changer must be made carefully and locked securely.
    • Assemble the tap leads so that they can be connected without using force.
    • If leads cross the oil compartment, maintain adequate clearance to the surface and live parts of the tap changer.

    Transformer Ratio Test

    • Perform a ratio test at low alternating current voltage before the transformer is dried.
    • Use a short tube with an inserted coupling bolt and a hand wheel or crank to operate the tap changer head.
    • One revolution of the drive shaft is required per step.
    • Reduce the number of tap change operations until the tap changer is filled with oil.

    Drying Process

    • The tap changer should be dried according to the following methods (6.11 or 6.12):
      • Vacuum drying in an autoclave: Heat up to 110°C, predry for 20 hours, vacuum dry for 100 hours at 10-3 bar residual pressure.
      • Vapor-phase drying: Apply kerosene vapor at 90°C for 3-4 hours, then increase the temperature to the desired level (maximum 125°C).
    • Do not operate the tap changer without oil after drying.

    Oil Filling

    • Replace the tap changer head cover after drying.
    • Tighten all 8 or 9 cover screws uniformly to a maximum torque of 34 Nm.

    Mounting the Protective Relay

    • Connect the protective relay (RS 2001) according to Operating Instructions No. 59.
    • Ensure the serial number on the relay matches the tap changer serial number.
    • Position the relay horizontally and as close to the tap changer head as possible.
    • The arrow on the relay should point toward the oil conservator.
    • Install a stop cock between the relay and oil conservator to prevent draining the conservator during tap changer inspections.

    Mounting the Motor Drive Unit, Bevel Gear, and Drive Shaft

    • The motor drive unit (MA 9 or MA 7) should be mounted vertically and protected from excessive vibrations.
    • Ensure the motor drive unit and tap changer serial numbers match.
    • Mount the bevel gear to a support on the transformer cover using two bolts.
    • Ensure the bevel gear serial number matches the tap changer serial number.
    • Assemble the drive shaft according to Operating Instructions No. 42.

    Inspections

    • Conduct inspections after 5-6 years regardless of the number of tap change operations.
    • The first inspection should be conducted after 1 year of service or 10,000 switching operations, whichever comes first.
    • Conduct further inspections every 2 years or 10,000 switching operations, whichever comes first.

    Drawing References

    • Installation drawings for models without change-over selector: N 1051
    • Installation drawings for models with change-over selector: N 1002
    • Dimension drawings of tap changer head for models without change-over selector: N 1162
    • Dimension drawings of tap changer head for models with change-over selector: N 1161
    • Drilling templates for tap changer head: 053 906 (without change-over selector), 053 907 (with change-over selector)
    • Dimension drawing for protective relay RS 2001: RSm 2001
    • Dimension drawing for motor drive unit MA 9: N 1255
    • Dimension drawing for motor drive unit MA 7: N 1267
    • Dimension drawing for bevel gear CD 6400: CDm 6400

    The text includes a detailed diagram of the tap changer with labels for all parts.

    Tap Changer Installation

    • Mounting flange is recommended for attachment to the transformer cover
    • Mounting flange should be made according to the gasket surface of the tap changer head
    • Drilling template is available for positioning studs (M12, max. length 45 mm)

    Tap Changer Attachment

    • Clean sealing surfaces
    • Apply oil-proof gasket to mounting flange
    • Carefully lower tap changer into the opening of the mounting flange
    • Ensure connecting contacts are not damaged
    • Verify correct tap changer head position
    • Secure tap changer head to the mounting flange

    Tapped Winding and Take-Off Lead Connection

    • Connect tap leads to the tap changer based on the provided connection diagram
    • Lead connections should be done carefully and securely locked
    • Ensure leads allow for connection without force
    • Maintain sufficient clearance between leads and oil compartment surface and live parts
    • Terminals are designated according to the connection diagram

    Transformer Ratio Test

    • Conduct ratio test at low AC voltage before transformer drying
    • Use a short tube (25 mm) with a coupling bolt (12 mm diameter) and a hand wheel or crank to operate the drive shaft
    • One revolution of the drive shaft is required per step
    • Selector switch operation should be audible
    • Do not exceed the end position indicated in the connection diagram
    • Use the inspection window to check the operating position
    • Minimize tap change operations until the tap changer is filled with oil
    • Return the tap changer to the adjustment position after the test

    Drying Process

    Vacuum Drying in the Autoclave

    • Remove the tap changer head cover
    • Heat the tap changer at a rate of 10°C/h to a maximum temperature of 110°C
    • Predry in circulating air at 110°C for 20 hours
    • Vacuum dry at 110°C with a maximum residual pressure of 10-3 bar for 100 hours

    Vapor-phase Drying Process

    • Open the kerosene drain plug
    • Remove the tap changer head cover
    • Apply kerosene vapor at 90°C for 3-4 hours
    • Increase the vapor temperature by 10°C/h to the required final temperature, with a maximum of 125°C
    • Tighten the kerosene drain plug after drying

    Oil Filling

    • Replace the tap changer head cover
    • Tighten all 8 or 9 cover screws M12 (wrench size 19, max. torque 34 Nm)

    Protective Relay Installation

    • Two connections R on the tap changer head can be used
    • Use a pipe connection with a flange to install the protective relay RS 2001
    • Install the protective relay according to Operating Instructions No. 59
    • Ensure the serial number matches the tap changer
    • Position near the tap changer head in a horizontal position
    • Arrow on the relay should point to the oil conservator
    • Pipe line to the conservator should have at least a 2% incline
    • Use a stop cock between the relay and the oil conservator

    Mounting the Motor Drive Unit, Bevel Gear, and Drive Shaft

    Motor Drive Unit Installation

    • Refer to Operating Instructions No. 80 for MA 9 or No. 40 for MA 7
    • Verify the motor drive unit and tap changer serial numbers match
    • Ensure both units are in the same operating position
    • Mount the motor drive unit vertically at the designated location on the transformer tank, protecting it from vibrations

    Bevel Gear Installation

    • Attach the bevel gear to a transformer cover support using two bolts (18 mm diameter)
    • Ensure the bevel gear serial number and tap changer serial number match

    Drive Shaft Installation

    • Assemble the drive shaft according to Operating Instructions No. 42
    • Connect the vertical part of the drive shaft between the motor drive unit and bevel gear
    • Connect the horizontal part of the drive shaft between the bevel gear and the tap changer head
    • Ensure the trunnions are properly aligned
    • Apply the same outside varnish as applied to the transformer tank to the square shaft

    Tap Changer Operation in the Transformer Factory

    Operational Tests

    • Verify mechanical operation of the tap changer and motor drive
    • Run the tap changer through the complete operating cycle
    • Confirm the indicators on the motor drive and tap changer head show the same position
    • Check for automatic electrical and mechanical limit stops in both end positions

    Oil Filling

    • Completely fill the tap changer with transformer oil through the oil conservator
    • Bleed the tap changer head using the bleeder screw in the head cover (M8, wrench size 13, max. torque 15 Nm)

    Ground Connections

    • Connect the ground screw on the tap changer head, head cover, and motor drive to the transformer cover or tank (wrench size 19, max. torque 60 Nm)

    Transformer Transportation

    • If the transformer is transported without the motor drive unit, set the motor drive to the adjustment position, uncouple it, and remove it
    • If the transformer is transported or stored without oil, drain the oil from the tap changer completely

    Inspections

    • Inspect the tap changing equipment at regular intervals
    • Ensure the inspection is done by qualified personnel adequately trained and organized
    • Consider having the Technical Service Department perform inspections to ensure proper execution and use of the latest designs
    • Regular testing of insulating oil is also recommended
    • Test the oil's dielectric strength and water content according to relevant standards
    • Submit inspection reports for reference

    Appendix

    • Appendix features installation and dimension drawings for different components of the tap changer
    • Includes specifications for standard values for oil testing
    • Provides references to relevant documents like IEC Publications and DIN standards

    Tap Changer Type A Overview

    • The tap changer type A is an on-load selector switch of tubular design.
    • The switch oil is separated from the transformer oil by an oil compartment cylinder.
    • The tap changer is attached to the transformer cover by its head, which connects the tap changer to the driving shaft.
    • Models without a change-over selector have up to 8 operating positions, models with a change-over selector have up to 15 positions.

    Installation

    • For mounting the tap changer head, use a flange soldered to the transformer cover.
    • Drill holes for studs (M12, 45 mm max) using a template (available upon request).
    • Connect tap leads to the tap changer according to the connection diagram provided.
    • Ensure all lead connections are secure and do not strain the tap changer.

    Transformer Ratio Test

    • Perform a ratio test with a low a.c. voltage before drying the transformer.
    • Operate the drive shaft by hand or with a hand crank for one revolution per step.
    • Connect the protective relay RS 2001 to the tap changer head.
    • Ensure the protective relay serial number matches the tap changer.
    • Place the relay close to the tap changer head, horizontally, with the arrow pointing towards the oil conservator.
    • Include a stop cock between the relay and the oil conservator.

    Motor Drive Unit and Bevel Gear

    • For mounting the motor drive unit, refer to operating instructions No. 80 for MA 9 or No. 40 for MA 7.
    • Ensure the serial number of the motor drive unit matches the tap changer.
    • Install the motor drive in a vertical position and protect it from excess transformer vibrations.
    • Attach the bevel gear to a support on the transformer cover using two bolts.
    • Ensure the bevel gear serial number corresponds to the tap changer.

    Drive Shaft Assembly

    • Assemble the drive shaft according to operating instructions No. 42.
    • Connect the drive shaft between the motor drive unit and the tap changer head, using coupling brackets and bolts.
    • Ensure the shaft and parts are properly aligned.
    • Cut the square shaft and foot step protection plate to size before mounting.

    Operational Tests

    • Before applying voltage, test the mechanical operation of the tap changer and motor drive, running through the complete operating cycle.
    • Check that the indicators on the motor drive and tap changer head show the same position.
    • Verify that the electrical and mechanical limit stops function in both end positions.

    Final Oil Filling and Electrical Tests

    • Fill the tap changer completely with oil via the oil conservator.
    • Bleed the tap changer head via the bleeder screw.
    • Connect the ground screw of the tap changer head and motor drive.
    • Perform transformer acceptance tests after completion.

    Transportation and Storage

    • If transporting without the motor drive unit, set the motor drive to the adjustment position, uncouple, and dismount.
    • If transporting or storing without oil, drain the oil completely and conserve the interior of the tap changer.
    • When in a prolonged stand-by, connect the heater of the motor drive unit to power.

    Putting into Operation at Site

    • Test the mechanical operation of the tap changer and motor drive.
    • Check the function of the protective relay, ensuring it is connected to the circuit breaker tripping circuit.
    • Verify that the circuit breakers switch off the transformer when the test push button is operated, and only switch on after the push button of the protective relay is pressed.
    • Ensure all stop valves between the oil conservator and tap changer head are open.

    Supervision and Failures

    • Inspect the tap changer head, protective relay, and motor drive unit regularly, paying attention to oil tightness, housing tightness, heater function, and control apparatus condition.
    • If the protective relay activates, inspect the tap changer and transformer.
    • In case of serious trouble, contact an authorized representative.
    • Never reconnect the transformer without prior inspection.

    Tap Changer Type A

    • Designed as a tubular selector switch which combines features of a diverter switch and a tap selector.
    • The tap changer oil compartment is separate from the transformer oil.
    • The tap changer is attached to the transformer cover by its tap changer head - which also connects the tap changer drive shaft and oil compartment to the conservator.
    • Models without change-over selector are available up to 8 operating positions, with change-over selector up to 15 positions.
    • Three-pole tap changers for star-connection: A III 100 Y (available with and without change-over selector)
    • Three-pole tap changers for any connection: A III 100 A (available with and without change-over selector)
    • Single-pole tap changers: A I 100 (available with and without change-over selector)

    Shipment

    • Tap changer and motor drive shipped in the adjustment position.
    • Store parts in a dry place until installed.
    • Tap changer should be left in its plastic cover until installation.
    • Shipped items include:
      • Tap changer type A (max weight 55kg)
      • Motor drive MA 9 (approx 60kg)
      • Motor drive MA 7 (approx 90kg)
      • Drive shaft parts with coupling parts and bevel gear (max 20kg)
      • Protective relay RS 2001 (3.5kg)

    Installation

    • Use a mounting flange soldered to the transformer cover for mounting the tap changer head.
    • Use a drilling template to position the studs for the tap changer head.
    • Clean sealing surfaces: tap changer head and mounting flange before installation.
    • Connect the tap leads to the tap changer according to the connection diagram.
    • All lead connections must be carried out carefully and locked securely.

    Testing and Operation

    • Perform a transformer ratio test at a low a.c. voltage before drying.
    • For testing, use a short tube with an inserted coupling bolt and a hand wheel or crank.
    • Ensure the selector switch operation is audible and that you do not exceed the end position.
    • After testing, return the tap changer to the adjustment position.
    • The tap changer should only be operated after being dried and filled with oil.

    Drying

    • Two main drying methods:
      • Vacuum drying: The tap changer head cover must be removed, and the tap changer undergoes a drying process in the autoclave at 110°C for 120 hours (20 hours predrying, followed by vacuum drying).
      • Vapor-phase drying: Kerosene vapor is applied at 90°C for 3-4 hours, then the temperature is increased to 125°C until the drying process is complete.

    Oil Filling

    • Replace the tap changer head cover.
    • Tighten all cover screws uniformly to 34 Nm.

    Protective Relay

    • The protective relay must be inserted into the tripping circuit of the circuit breakers.
    • The protective relay must disconnect the transformer immediately when activated.
    • The circuit breakers should only be able to switch on the transformer once the protective relay's “IN SERVICE” button is activated.

    Supervision and Maintenance

    • Regularly inspect the tap changer head, protective relay, and motor drive unit.
    • Inspect seals, tightness of motor drive housing, operational heater, and the condition of the motor drive control apparatus.
    • In the event of a protective relay response, thoroughly inspect the tap changer and transformer, including the selector switch unit.
    • Contact authorized MR representative, transformer manufacturer, or Maschinenfabrik Reinhausen GmbH for serious trouble or repairs.

    Inspections

    • Regular inspections are recommended to maintain reliability.
    • Inspections can be performed by qualified personnel in one day with proper preparation and organization.
    • MR Technical Service Department is recommended for inspections, as they can ensure expert execution and component retrofits.
    • Oil dielectric strength and water content must comply with relevant standards.
    • Send inspection reports to MR for record keeping.

    Oil Testing Standard Values

    • The following values according to CIGRE report 12-13 (1982) should be tested at service temperature:
      • Water content:
        • A III 100 Y < 40 ppm
        • A III 100 Δ, A I 100 < 30 ppm
      • Dielectric Strength:
        • A III 100 Y > 30 kV/2.5 mm
        • A III 100 Δ, A I 100 > 40 kV/2.5 mm

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    On-Load Tap Changer Type A Operating Instructions PDF

    Description

    Test your knowledge on the features and installation of On-load Tap Changer Type A. This quiz covers its components, shipment, installation procedures, and connection guidelines. Perfect for those studying electrical transformer technology.

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