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Questions and Answers
What is the maximum rated through-current of a three-phase VACUTAP® VRF OLTC as indicated in the type identification?
In the context of VACUTAP® VR, how many operating positions does the tap selector system have, including the mid-position?
Which of the following components is used specifically as a coarse tap selector in the VACUTAP® VR operations?
What type diagram is associated with the three-phase VACUTAP® VRF OLTC as mentioned in the documentation?
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What is the pitch of the tap selector contact circle for the three-phase VACUTAP® VRF OLTC?
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What action should be taken to prevent damage to the OLTC when using the motor drive unit?
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What should be noted before removing the diverter switch insert?
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What is the primary safety precaution to take before carrying out maintenance work on OLTCs?
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What is the risk associated with switching oil in the OLTC?
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What should be performed before opening the head cover on the OLTC?
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Which auxiliary equipment is necessary for servicing OLTCs, according to the preparation instructions?
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Which component must be actuated to block the motor drive unit against electrical operation?
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What should be done with the transformer terminals before maintenance on OLTCs?
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What is the maximum weight mentioned for the diverter switch insert during maintenance?
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What is the primary purpose of the tap position indicator?
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In what condition is it safe to operate the motor drive unit?
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What type of damage may potentially occur if proper precautions are not taken during OLTC maintenance?
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What is essential to view before performing maintenance on the motor drive unit?
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Which item is NOT listed as necessary tools for OLTC maintenance?
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What is indicated as a risk of electric shock during OLTC maintenance?
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What type of rags are recommended for cleaning during OLTC maintenance?
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Which step needs to be performed before removing the coupling tube from the diverter switch insert?
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What is the maximum tightening torque for the screws when removing the coupling tube?
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What should be checked for during the visual inspection of the coupling tube?
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What must be ensured regarding the coupling tube upon reassembly?
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What is advised regarding the diverter switch insert during tap change operations?
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Which of the following is NOT a step in checking the coupling tube?
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What might indicate a significant problem with the coupling tube?
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Why should any damaged parts be replaced immediately?
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What is the recommended service interval for the tap selector maintenance?
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Which component is to be replaced after 1.2 million tap change operations?
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Who should be contacted for technical service regarding maintenance?
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In what order should the diverter switch insert be reinstalled?
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What is the purpose of a varistor in electrical systems?
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What is the significance of the information provided in figures 24 to 34?
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Where is the MR Technical Service located?
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What does the complete diverter switch require after 1.2 million tap change operations?
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It is safe to perform tap change operations of the diverter switch without the head cover in place.
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Removing the head cover requires loosening 20 screws with locking washers.
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It is essential to ensure that no small parts are dropped into the diverter switch oil compartment during maintenance.
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The round rubber gasket is not required to prevent damage during disassembly.
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Care must be taken to prevent the OLTC from blocking during the removal of the diverter switch insert.
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The head cover can be removed without any specific tool requirements.
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The diverter switch insert must be removed after moving the OLTC into a special adjustment position.
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The installation of the head cover should use mismatched screws to ensure a tight fit.
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OLTCs must be serviced after 300,000 tap change operations.
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The insulating oils in the transformer can be monitored by anyone, without any specific qualifications.
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Functional tests of the protective relay should be performed according to Operating Instructions No. 59.
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Regular inspections of the OLTC head, the protective relay, and the motor drive unit are discouraged.
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Proper function of the in-built electric heater in the protective housing is a maintenance priority.
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The state of the dehydrating breather for the OLTC should be monitored as part of regular maintenance.
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Maintenance reports do not need to be forwarded if the service is conducted by trained personnel.
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Gaskets of the protective housing do not require inspection during maintenance.
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The diverter switch insert can be safely operated while removed from the system.
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The coupling tube needs to be cleaned with transformer oil to maintain its integrity.
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Mechanical or electrical damage can be identified by conducting a visual inspection of the coupling tube.
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The 6 screws removed during the coupling tube check should be tightened to a torque of 50 Nm.
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The position of the hole at the top of the coupling tube is not critical during reassembly.
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Reassembly of the coupling tube can be done in any order after removal.
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Checking the coupling tube is only necessary for three-phase OLTCs.
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Spacer sleeves are not involved in the maintenance of the coupling tube.
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The automatic switch-off function of the OLTC should only be tested in one end position.
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Operating Instructions No. 42 details the procedure for installing the drive shaft.
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The transformer can be switched on immediately after completing the required checks.
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The bleeding procedure involves connections detailed in Operating Instructions No. 138.
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A careful visual inspection of the coupling tube is deemed unnecessary during OLTC maintenance.
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Before applying voltage, some test operations must be conducted to check the mechanical functions of the tap changer.
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Section 8 is dedicated to further checks that need to be performed before operating the OLTC.
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The operation of the OLTC can be carried out without adhering to the cautionary notes provided.
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Pressing the 'ON' button on the protective relay while in the danger zone of the transformer is safe.
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The protective relay must be reset by pressing the 'OFF' button after conducting an active protection test.
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The circuit breaker should remain closed during the passive protection test of the transformer.
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After a protective relay is triggered, the diverter switch insert must be inspected as per maintenance instructions.
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The OLTC and transformer are not at risk of damage if the instructions are followed correctly during maintenance.
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Leaving the danger zone of the transformer is unnecessary after pressing the 'OFF' button on the protective relay.
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The circuit breaker of the transformer must remain open after resetting the protective relay.
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In the event of major faults, contacting the transformer manufacturer is optional.
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What does the warning signal word 'CAUTION' indicate?
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Which pictogram represents a warning of combustible substances?
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What kind of information is mainly provided to simplify procedures?
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Which statement represents a critical point in the maintenance procedure for OLTCs?
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Which of the following indicates that a hazardous situation could lead to death or serious injury?
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What is the primary purpose of using signal words in notices?
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What kind of hazard does the pictogram indicating dangerous electrical voltage warn against?
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Which statement about the general safety information is false?
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What could potentially block the diverter switch insert during maintenance?
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What is essential to ensure when removing the tap position indicator from a multiple coarse change-over selector?
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Which component must be handled carefully to avoid damaging the tap position indicator during removal?
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What is necessary to perform after removing the hexagon screws during the removal of the diverter switch insert?
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What should be checked in preparation for removing the diverter switch insert?
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What might indicate a potential problem during the disassembly of the diverter switch insert?
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Which tool is necessary for leveraging off the cover disk when accessing the position-indication disk?
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What ensures that the product does not present hazards throughout its entire life cycle?
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What must be ensured regarding the diverter switch oil compartment before starting maintenance work?
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Which of the following represents inappropriate use of the product?
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What must be done to avoid liability for damage related to the product?
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Which aspect is a strict requirement for the product's operational safety?
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What is deemed inappropriate regarding product operation?
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Which of the following statements reflects the importance of using specified equipment?
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What is a key consideration regarding changes to the product?
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What is primarily ensured by maintaining compliance with the specified requirements?
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What should be ensured for safe operation regarding the hand crank used for manual operation of the motor-drive unit?
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What is a crucial step to prevent damage to the on-load tap-changer when performing operations?
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Which precaution must be taken before starting any coupling work on the motor-drive unit?
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What must be done before actuating the on-load tap-changer after drying the transformer?
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What is an essential condition to fulfill when inserting a diverter switch insert?
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In what scenario might the control circuit still be active even when the hand crank safety switch is engaged?
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What should be verified regarding the cardan shafts during maintenance of special design types?
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What is the outcome of performing too many operations on the on-load tap-changer without complete oil filling?
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What is the importance of continuing to turn the hand crank until the mid-position is reached during on-load tap-changing operations?
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What is the required tightening torque for refitting the vertical drive shaft of the motor-drive unit?
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When operating the motor-drive unit using the hand crank, which direction should the crank be turned?
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What happens if the on-load tap-changer is not coupled correctly during operation?
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What action is specifically NOT required when determining the sectors needed for tap-changing operations?
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During the on-load tap-changing operation, what must be done after noting the determined value A?
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What safety precaution is emphasized regarding the hand crank during operation?
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What is a critical danger if the on-load tap-changing operation is incomplete?
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It is mandatory to visibly connect all transformer terminals to ground and short circuit them before performing maintenance.
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An energized transformer poses no risk of injury during maintenance as long as the maintenance team is careful.
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Before maintenance, the transformer needs to be switched off and locked to prevent unintentional restart.
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Regular cleaning rags are suitable for use during the oil change of an on-load tap-changer.
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The oil quantity for cleaning and oil change is the same regardless of the on-load tap-changer type and its rated voltage Um.
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The oil level in the on-load tap-changer rises automatically when the drain valve is opened.
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It is safe to operate electric devices during maintenance work on the on-load tap-changer.
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The on-load tap-changer head can be opened without first de-energizing the tap-change supervisory control.
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The sealing surfaces on the on-load tap-changer head cover must be in sound condition before removing it.
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Ten liters of oil should be drained from the on-load tap-changer before sealing the air-vent valve E1.
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Head cover removal of the on-load tap-changer requires the loosening of specifically five screws.
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All auxiliary circuits must be energized before opening the head cover of the on-load tap-changer.
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Removal of the diverter switch insert must be done without concern for additional parts falling into the oil compartment.
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The VACUTAP® VR II III series requires maintenance after 500,000 tap change operations.
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The dielectric strength of diverter switch oil is assessed only after maintenance procedures.
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The head cover of the OLTC can be removed without any tools.
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During the maintenance of an OLTC, the insulating oils can be checked by unqualified personnel.
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Removing the diverter switch insert requires moving the OLTC into a specific adjustment position.
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The protective relay must be functionally tested according to Operating Instructions No. 56.
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Mismatched screws should be used for the installation of the head cover in the OLTC.
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Regular inspections of the OLTC head, protective relay, and motor drive unit are encouraged.
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Cleaning and inspecting the diverter switch insert is a step included in the maintenance of the OLTC.
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The oil level in the diverter switch oil compartment should be raised before removing components.
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Replacing vacuum interrupters is not listed as a task during OLTC maintenance.
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The tap-change supervisory control is optional and not always present in the OLTC.
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Dielectric strength and water content limits for on-load tap-changer oil can be found in the appendix.
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The primary purpose of a safety precaution is to ensure the safe removal of the OLTC electric motors.
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The hand crank should be turned in the opposite direction of the tap-change indicator during operation.
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A correction value must be calculated for every on-load tap-changing operation.
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The mid-position on the tap-change indicator is identified by a gray area.
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If the determined value during operation is less than 8 tap-change indicator sections, no further action is required.
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The tightening torque for the vertical drive shaft should be 15 Nm during assembly.
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Turning the hand crank past the mid-position can lead to severe damage or injury.
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Each section on the tap-change indicator represents 1.0 tap-change indicator sections.
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The motor-drive unit can be coupled to the on-load tap-changer in any alignment.
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The silver coating on the contacts inside the diverter switch oil compartment must be discolored for proper function.
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New transformer oil should be used to clean the diverter switch insert.
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Mechanical or electrical damage should be investigated only under dim lighting conditions.
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Phantom images can be documented with a camera to indicate defects in the oil compartment.
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The coupling tube does not need to be removed for inspection of the diverter switch insert.
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Six screws hold the lower screening ring of the coupling tube in place.
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The diverter switch oil compartment can be uncovered once a year for inspection.
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Spacing sleeves are not required for the maintenance of the coupling tube.
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What is the first step before removing the on-load tap-changer head cover?
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What must be done to lower the oil level in the diverter switch oil compartment?
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Which tool is suggested to actuate the valve tappet on the air-vent valve E1?
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What is advised to avoid losing during the removal of the horizontal drive shaft?
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In what situation should the coupling brackets be loosened?
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What is the significance of closing the stop-cock between the oil conservator and on-load tap-changer?
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What procedure should be followed after lifting the valve tappet on the air-vent valve E1?
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What is the primary requirement for personnel conducting maintenance on the on-load tap-changer?
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What should be done after loosening the screws on the coupling brackets?
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What document should be forwarded to update maintenance files after performing maintenance by unapproved personnel?
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Why is it necessary to check the dielectric strength of diverter switch oil after maintenance?
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What should be done with the dielectric strength measurements of the diverter switch oil?
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What is the maximum time recommended for maintenance of an on-load tap-changer pole when well prepared?
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What specific information must be included in inquiries about spare parts?
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How should maintenance intervals be determined?
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What is a crucial factor for ensuring efficient maintenance of the on-load tap-changer?
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What is the structure of single-step instructions in the technical file?
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Which pictogram indicates a warning of dangerous electrical voltage?
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What is a required step before the maintenance of OLTCs?
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What should be included in multi-step instructions according to the technical file structure?
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Which type of warnings are indicated by pictograms in the technical file?
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What type of information is crucial in the instruction system of the technical file?
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Which additional component is often considered non-essential during maintenance of OLTCs?
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What should be avoided during the removal of the diverter switch insert?
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What is the recommended action for replacing fixed main contacts for models other than VR I 1601/1801 after a specified number of operations?
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What must be inspected visually in the maintenance of the protective relay?
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How often should the tap selector be maintained according to the provided guidelines?
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What is the required retaining force of the flap valve during inspection?
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For models VR I 1601/1801, after how many tap change operations should the fixed main contacts be fully replaced?
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What should be done to the protective relay before replacing the seal in the cover?
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What is the purpose of replacing the fixed main contacts after specified operations?
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What tool is recommended for cleaning the protective relay?
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What is crucial to ensure when filling the diverter switch oil compartment with insulating oil?
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What procedure must be followed regarding the o-ring when installing the on-load tap-changer head cover?
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Which steps should be ensured when securing the cover disk with a countersunk head screw?
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What alignment is necessary when placing the head cover on the on-load tap-changer?
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What should be checked regarding the sealing surfaces before inserting a new o-ring?
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Which of the following is a potential consequence of a damaged o-ring in the diverter switch?
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What type of screw is specified for securing the cover disk?
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What might happen if improper insulating oil is used in the diverter switch?
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Qualified personnel can usually perform maintenance on an on-load tap-changer pole within two days.
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The dielectric strength of diverter switch oil must comply with set limit values during both operation and after maintenance.
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Reports on maintenance performed should be sent to ensure updates to maintenance files.
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The dielectric strength of the diverter switch oil does not need to be checked after maintenance.
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All maintenance should be conducted by the Technical Service department to ensure safety and compliance.
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A fax template for reporting maintenance is provided in the appendix for convenience.
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The limit values for dielectric strength and water content are only applicable during maintenance periods.
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Maintenance of the on-load tap-changer can be completed irrespective of the serial number provided.
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The on-load tap-changer can have a maximum of 35 operating positions with a change-over selector.
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The type designation of an on-load tap-changer does not provide any information on the maximum rated through current.
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Inspection of the OLTC head and motor drive unit is considered unnecessary by default.
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The pitch of the tap selector is indicated in the type designation for the VACUTAP® VRF.
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The diverter switch insert must be left in place during maintenance to avoid damage.
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The highest voltage for equipment Um in the type designation is measured in volts.
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OLTCs should undergo service every 300,000 tap change operations.
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The tap position indicator is used to determine the maximum operating position of an OLTC.
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The VACUTAP® VRD/VRF has a selector size identified as E/F.
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The adjustment plan for VACUTAP® VRC with multiple coarse change-over selector is designed for change-over selector division 10.
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Technical service for maintenance of OLTCs is generally recommended to be performed by personnel without specific qualifications.
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The diverter switch oil's dielectric strength and DC resistance measurement are part of the maintenance scope.
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The VACUTAP® VRF adjustment plan allows for both change-over and coarse tap selector connections.
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Operating the motor-drive unit is safe even if the horizontal drive shaft has been removed.
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A specific adjustment plan exists for the VACUTAP® VRG that utilizes a reversing change-over selector connection.
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The adjustment plan without change-over selector for the VACUTAP® VRF is designated as model number 10016148.
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It is necessary to ensure that no ignition sources are present when working with the on-load tap-changer due to explosive gases.
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The number 2343791 refers to a different version of VACUTAP® than the one labeled 2343791/02 EN.
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Conductive and grounded hoses that are approved for flammable liquids must not be used during maintenance.
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The head cover of the on-load tap-changer requires no specific tools for removal.
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Vacutap® VRC is described as having coarse tap connections with specific divisions.
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Damage to the on-load tap-changer can occur if the motor-drive unit is operated while not coupled.
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Adjustment plans for VACUTAP® VR are outlined only for the RC/RD series.
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VACUTAP® VRC, adjustment plan for division 12, provides four coarse tap connections.
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Regular inspections of the OLTC head, protective relay, and the motor drive unit are encouraged.
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The instruction document contains detailed information about the performance of the tap selector system.
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The diverter switch insert must be removed after the on-load tap-changer is placed into a normal operating position.
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Explosive gases may be present under the on-load tap-changer head cover.
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The maximum measured current for a filled oil compartment during a DC resistance measurement is 50 A DC regardless of whether the current is interrupted.
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DC resistance measurements on transformer windings can exceed 10% of their rated current if the winding is not overheating.
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It is permissible to measure DC resistance with a maximum of 10 A DC in an empty oil compartment without interrupting the measured current.
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When the measured current is interrupted before changing the operating position, the maximum allowed current remains the same as when it is uninterrupted.
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Performing maintenance on an energized transformer can lead to severe injury or even death.
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The maximum current for measuring DC resistance should always be kept at 50 A DC for safety reasons in any scenario.
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The risk of electric shock during OLTC maintenance is eliminated by ensuring the transformer is de-energized.
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DC resistance measurements should not be conducted while the transformer is under load.
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Study Notes
Preparation for OLTC Maintenance
- Ensure safety by switching off the transformer and securing against reactivation.
- Connect all transformer terminals to ground and short-circuit them to prevent electric shock.
- Required auxiliary equipment includes clean barrels, transformer oil, an oil pump, absorbent cleaning rags, a workbench, an oil sump, and lifting devices.
- Maximum weight of the diverter switch insert is 50 kg; withdrawal height depends on OLTC type and rated voltage.
- Use appropriate tools and fixtures as specified in technical documentation.
General Information on OLTCs
- On-load tap-changers (OLTCs) are categorized with unique type identifications for different versions.
- Example: VACUTAP® VRF OLTC has a max rated current of 1300 A and voltage rating up to 72.5 kV.
- Tap selector size and operating positions must be noted; mid-position is one of the operating positions.
Operations and Maintenance
- Never operate the motor drive unit while uncoupled from the OLTC.
- Maintain the adjustment position before removing the diverter switch insert.
- Lower oil level in the oil compartment prior to opening the head cover due to flammable liquid risks.
- Inspect and clean the coupling tube and ensure it is free of mechanical or electrical damage.
- Reassemble parts ensuring correct positioning according to adjustment markers.
Maintenance Procedures
- Diverter switch inserts must be replaced after 1.2 million tap change operations.
- Fixed main contacts also require replacement following the same tap change operation threshold.
Technical Service Contact
- For maintenance queries or parts replacements, contact MR Technical Service (Maschinenfabrik Reinhausen GmbH):
- Address: P.O. Box 12 03 60, 93025 Regensburg, Germany
- Phone: +49 94140 90-0
- Fax: +49 941 40 90-501
- Email: [email protected]
- Website: www.reinhausen.com
Installation Guidelines
- Reinstall the diverter switch insert by reversing the removal steps, following detailed figures in technical documentation to ensure correct assembly.
OLTC Maintenance and Inspections
- Occasional visual inspections of the OLTC head, protective relay, and motor drive unit are essential for early damage detection.
- Regular servicing of OLTCs is crucial to maintain high operational reliability.
- Key inspection areas include oil tightness at sealing locations, gaskets of the protective housing, and the state of the dehydrating breather.
- Functional tests of the protective relay should be performed according to Operating Instructions No. 59.
- Insulating oils must be monitored to ensure their quality and proper function.
Maintenance Intervals and Protocol
- OLTCs require servicing after 300,000 tap change operations; the motor drive unit has an operation counter.
- Personnel performing maintenance should be trained or qualified by MR to ensure compliance and safety.
- Maintenance reports must be forwarded for documentation and record-keeping.
Safety Precautions
- Avoid tap change operations without the head cover to prevent damage to the diverter switch.
- Ensure all screws and small parts are accounted for during disassembly and reinstallation to avoid blockages and operational hazards.
Removing and Inspecting Components
- Head cover removal requires careful handling of 24 screws (M10/w.s.17); avoid damaging faying surfaces.
- Check and clean the coupling tube, inspecting for leaks or discharge tracking.
- Reinstallation must align the coupling tube's position with the adjustment marker.
Functional Testing and Further Checks
- Perform mechanical function checks before voltage application to the transformer, making sure to run the tap changer through the entire operating range.
- Check protective relay functionality by conducting both passive and active protection tests.
Technical Support and Further Assistance
- Contact MR Technical Service for any major issues or if the protective relay triggers, providing them with pertinent details for further support.
Signal Words in Warning Notices
- WARNING: Indicates hazardous situations that could lead to death or serious injury if not avoided.
- CAUTION: Indicates situations that may result in minor or moderate injury if not addressed.
- NOTICE: Indicates necessary measures to prevent property damage.
Pictograms for Dangers
- Danger Point: Warns of a danger point.
- Electrical Voltage: Alerts to the presence of dangerous electrical voltage.
- Combustible Substances: Indicates the risk of combustible materials.
- Tipping Risk: Warns of danger related to tipping hazards.
Safety Information
- The technical file contains detailed maintenance procedures to ensure safe product use.
- Appropriate Use: Adheres to legislation and health/safety standards throughout the product's lifecycle—from delivery to disposal.
- Product maintenance must follow specified technical guidelines, using appropriate tools and equipment.
Inappropriate Use
- Use beyond prescribed guidelines is deemed inappropriate; manufacturers do not accept liability for such misuse.
- Unauthorized modifications can lead to personal injury or property damage.
Removal and Maintenance Guidelines
- Removal of the tap position indicator requires specific steps such as removing the spring clip and countersunk head screws.
- Care must be taken to keep track of parts to ensure proper reassembly.
Inserting Diverter Switch Insert
- During coupling work, ensure the motor protective switch is off to prevent accidental start-up.
- Manual operation should be conducted with the designated hand crank only.
Operational Warnings
- WARNING: Incomplete operations could lead to severe injury or property damage, emphasizing the need to complete all tasks before concluding the tap-changing process.
- NOTICE: Limit tap-change operations without oil to prevent damage to the on-load tap-changer; ensure complete oil filling before first activation post-drying.
General Operations
- Continuation of turning during the tap-changing operation is critical for correct functionality.
- Identification of directional rotation is necessary for proper operation and safety.
Introduction to Maintenance Manual
- Maintenance manual for VACUTAP® VR II III on-load tap-changer, covering safe and proper maintenance procedures.
- Important notes on validity, completeness, and potential changes in product information.
- Supporting documents and notation conventions detailed for clarity.
Safety Considerations
- General safety practices emphasized to prevent death or severe injury during maintenance.
- Mandatory safety precautions include switching off, locking, grounding, and ensuring de-energization of transformers.
- Outline of necessary auxiliary equipment such as oil pumps, cleaning tools, and containers for oil changes.
Operational Surveillance
- Monitoring during operation to ensure safe functioning and early identification of potential issues.
Product Overview
- Functionality and setup of on-load tap-changer are described, highlighting various models and type designations.
Maintenance Protocols
- Detailed scope of maintenance includes intervals for dielectric strength checks and DC resistance measurements.
- Specific measures for assessing dielectric strength of diverter switch oil, both during operation and after maintenance.
Preparation for Maintenance
- Essential safety precautions and equipment needed prior to servicing.
- Steps for adjusting the on-load tap-changer and ensuring readiness for maintenance tasks.
Diverter Switch Insert Removal
- Comprehensive steps for removing the diverter switch insert, including precautions around energized systems and explosive gases.
- Importance of checking sealing surfaces and o-rings during maintenance to avoid contamination.
Maintenance Procedures
- Cleaning and inspecting the diverter switch oil compartment and ensuring proper functioning of switch components.
- Specific procedures for replacement parts including vacuum interrupters, varistor connection leads, and main contacts.
Reassembly Process
- Protocols for correctly re-inserting diverter switch components and ensuring oil levels are adequate.
- Guidelines for securing and testing the operational readiness via trial tap-change operations and setting mechanical stops.
Commissioning the Transformer
- Procedures for commissioning the transformer post-maintenance to ensure all systems are operational and safe.
Additional Information
- Maintenance schedules and limit values for dielectric strength and water content of tap-changer oil provided in the appendix.
- Detailed tap-change processes, switching sequences, and adjustment plans for specific VACUTAP® models, catering to different configuration needs.### Checking Diverter Switch Oil Compartment
- Inspect fixed oil compartment contacts and the interior of the diverter switch oil compartment using a mirror and lamp.
- Ensure the silver coating on the contacts remains undamaged and not discolored.
- Conduct thorough inspections for mechanical or electrical damage, such as creapage paths or discharge signs, under good lighting.
- Use a camera to document any defects found during inspection.
- After inspections, cover the diverter switch oil compartment with the on-load tap-changer head cover.
- For uncertainties, contact MR Technical Service; providing photographs of defects can be beneficial.
Cleaning and Inspecting Diverter Switch Insert
- Use only new transformer oil for cleaning the diverter switch insert to avoid damage.
- Perform a detailed visual inspection of the diverter switch insert.
- Under adequate lighting, check for any mechanical or electrical damage.
Inspecting Coupling Tube
- Remove the coupling tube from the diverter switch insert for inspection.
- Detach the lower screening ring by removing six screws securing it.
- Extract the six spacing sleeves with pliers once the lower screening ring is lifted.
- Carefully pull off the coupling tube and clean it with transformer oil.
- Operate the motor-drive unit using the hand crank in the same direction to reach specific tap-change indicator sections.
- Reattach the vertical drive shaft to connect the motor-drive unit and on-load tap-changer, ensuring a tight torque of 9 Nm.
Safety Precautions for On-load Tap-changer Operation
- Complete any on-load tap-changing operation to avoid potential dangers, such as incomplete processes that can lead to severe injury or property damage.
- Always continue turning the hand crank in the same direction until reaching the mid-position on the tap-change indicator column.
- Ensure the coupling is correct to facilitate safe operation without needing to calculate correction values.
Pictograms and Warning Notices
- Pictograms are used to communicate specific dangers.
- Key warning pictograms include:
- Danger point warning
- Dangerous electrical voltage warning
- Combustible substances warning
- Tipping hazard warning
Information and Instruction Systems
- Information presentation simplifies understanding of procedures.
- Contains both single-step and multi-step instructions:
- Single-step instructions follow a simple structure of aim, requirements, action steps, and results.
- Multi-step instructions involve a sequence of steps with individual results noted for each action.
Safety and Maintenance Protocols
- General safety guidelines provide comprehensive product maintenance instructions.
- Thoroughly read the technical file to ensure proper product usage.
- Maintenance should be performed by qualified personnel and can often be done within one day per on-load tap-changer pole.
- Maintenance reports need to be forwarded to maintain regulatory compliance and updates.
Oil Management and Testing
- Dielectric strength tests are crucial during and after maintenance to ensure safety:
- Check oil dielectric strength in the diverter switch oil compartment.
- The oil level must be lowered before opening the on-load tap-changer head cover.
- Procedures are in place for handling oil levels and screw caps to prevent contamination or damage.
Maintenance Intervals and Requirements
- Fixed main contacts must be replaced after a specific number of tap change operations:
- 1.2 million operations for most types.
- 300,000 operations specifically for VR I 1601/1801 models.
- Maintenance of the tap selector is required after 1.2 million operations.
Conducting Electrical and Mechanical Inspections
- Protective relay inspection involves cleaning, measuring retaining forces, and visual checks of magnetic switches.
- Special attention to the positioning of components and seals during reassembly to prevent leaks.
Finalizing Maintenance Procedure
- Proper filling of the diverter switch oil compartment is critical:
- Insulating oil must meet dielectric strength and water content specifications.
- A new o-ring must be installed correctly to prevent oil leaks.
- Ensuring proper alignment of the on-load tap-changer head cover during installation is essential for operational integrity.
VACUTAP® Overview
- VACUTAP® on-load tap-changer models include various selector sizes and adjustment plans for specific applications.
- Available models include VRF, VRC I/VRE I, VRD, and VRG, each with specific configurations and selector connection types, such as coarse and change-over selectors.
Configuration and Design
- On-load tap-changer is divided into components: head, diverter switch oil compartment, and tap selector.
- Standard models operate without a change-over selector, offering a maximum of 18 positions, while models with a change-over selector can accommodate up to 35 positions.
- Type designation includes model abbreviations, phase count, current ratings, voltage levels, tap selector size, and operational settings.
Maintenance Guidelines
- Maintenance should ideally be performed by trained personnel or the manufacturer's Technical Service to ensure efficiency and safety.
- Maintenance procedures can often be completed in one day if adequately organized.
- Required maintenance tasks include checking dielectric strength of diverter switch oil and monitoring DC resistance of transformer windings.
Safety Precautions
- Strict safety measures are vital due to the risk of electric shock and explosion.
- Precautions include ensuring no ignition sources and de-energizing circuits before maintenance begins.
Measurement Considerations
- DC resistance measurements require restricting current to prevent overheating, with set maximums based on the oil compartment's status and the method used.
- Measurements should account for operational position changes and the timing of current interruptions.
Preparatory Steps for Maintenance
- Record current position and change to adjustment position as per connection diagrams.
- Implement safety protocols to mitigate risks associated with energized components.
Diverter Switch Insert Removal
- Removal of the diverter switch insert must follow strict safety and procedural guidelines to avoid damage or personal injury.
- Precautions include blocking the motor-drive unit to prevent unauthorized operation during maintenance.
Important Maintenance Components
- Serious danger exists with explosive gases in maintenance areas, necessitating a no-ignition environment.
- Conductivity and grounding of hoses and pumps must be ensured when working with flammable substances.
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This quiz focuses on the critical safety procedures and auxiliary equipment related to the Motor Drive Unit as outlined in document WA 290/02 - VACUTAP® VR. Test your knowledge on the key practices and equipment necessary for safe operation. Ideal for professionals working in electrical engineering and maintenance.
