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Questions and Answers
What should be done to position the OLTC insert correctly?
What should be done to position the OLTC insert correctly?
What is the purpose of the operating key during the adjustment process?
What is the purpose of the operating key during the adjustment process?
Which step is crucial before reinstalling the gear mechanism?
Which step is crucial before reinstalling the gear mechanism?
What must be done with the screws when attaching the gear mechanism supporting plate?
What must be done with the screws when attaching the gear mechanism supporting plate?
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What is the final step after filling the oil compartment?
What is the final step after filling the oil compartment?
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What is the role of the change-over selector in the adjustment process?
What is the role of the change-over selector in the adjustment process?
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What type of oil should be used for filling the oil compartment?
What type of oil should be used for filling the oil compartment?
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What should be done after adjusting the position of the gear mechanism?
What should be done after adjusting the position of the gear mechanism?
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What should be done if the O-ring gasket is found to be in poor condition?
What should be done if the O-ring gasket is found to be in poor condition?
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What is the maximum torque specified for the attachment of the head cover bolts?
What is the maximum torque specified for the attachment of the head cover bolts?
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What should be checked before returning the transformer to service?
What should be checked before returning the transformer to service?
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What is the maximum torque that should be applied to the screw cap M16/w.s. 22?
What is the maximum torque that should be applied to the screw cap M16/w.s. 22?
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Which component is referenced for checking the electrical and mechanical end position of the motor drive unit?
Which component is referenced for checking the electrical and mechanical end position of the motor drive unit?
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What action should be taken if the protective relay responds during the operational test?
What action should be taken if the protective relay responds during the operational test?
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When preparing to bleed the tap changer head, what initial step is required?
When preparing to bleed the tap changer head, what initial step is required?
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What is necessary to ensure when operating the stop valve between the oil conservator tank and tap changer head?
What is necessary to ensure when operating the stop valve between the oil conservator tank and tap changer head?
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Which step must be taken before operating and bleeding the stationary oil filter unit?
Which step must be taken before operating and bleeding the stationary oil filter unit?
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What is the primary function of the protective relay mentioned in the content?
What is the primary function of the protective relay mentioned in the content?
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In what situation should the tap changer not be reconnected?
In what situation should the tap changer not be reconnected?
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In case of an operational test, how should the ground connections be handled?
In case of an operational test, how should the ground connections be handled?
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What is the function of the spring washers mentioned in the attachment of the head cover?
What is the function of the spring washers mentioned in the attachment of the head cover?
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What should be checked as part of the operational test of the protective relay?
What should be checked as part of the operational test of the protective relay?
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What should be done if serious trouble with the tap changer or motor drive occurs?
What should be done if serious trouble with the tap changer or motor drive occurs?
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What is NOT a prerequisite for testing the protective relay according to the provided guidelines?
What is NOT a prerequisite for testing the protective relay according to the provided guidelines?
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What is the primary purpose of the tap change indication wheel?
What is the primary purpose of the tap change indication wheel?
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How many sections are there on the tap change indication wheel in case of MA 8 motor drive?
How many sections are there on the tap change indication wheel in case of MA 8 motor drive?
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What should be ensured during the adjustment of symmetrical coupling?
What should be ensured during the adjustment of symmetrical coupling?
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What is the consequence of minor asymmetry in the tap change operation?
What is the consequence of minor asymmetry in the tap change operation?
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From which point is the section count measured during the tap change operation?
From which point is the section count measured during the tap change operation?
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What is indicated by the red center mark on the tap change indication wheel?
What is indicated by the red center mark on the tap change indication wheel?
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What does the 'diverter switch' refer to in the provided content?
What does the 'diverter switch' refer to in the provided content?
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In the context of the tap change operation, what does each section of the indication wheel represent?
In the context of the tap change operation, what does each section of the indication wheel represent?
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Which type of wrench is correctly matched with its corresponding DIN and wrench size?
Which type of wrench is correctly matched with its corresponding DIN and wrench size?
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What is the DIN designation for the double-ended socket wrench listed?
What is the DIN designation for the double-ended socket wrench listed?
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Which size corresponds with the hexagon socket screw key
Which size corresponds with the hexagon socket screw key
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Which wrench type uses a double-ended configuration?
Which wrench type uses a double-ended configuration?
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How many types of wrench are listed under DIN designation A | 895?
How many types of wrench are listed under DIN designation A | 895?
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What is the purpose of the tools listed in the context?
What is the purpose of the tools listed in the context?
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What does the size designation '17x19' refer to?
What does the size designation '17x19' refer to?
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Which operating key fits with the withdrawal and reinstallation of the OLTC insert?
Which operating key fits with the withdrawal and reinstallation of the OLTC insert?
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The OLTC insert should be cleaned only after it has been removed from the gear mechanism.
The OLTC insert should be cleaned only after it has been removed from the gear mechanism.
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The inspection intervals for the OLTC insert are determined by the age of the equipment.
The inspection intervals for the OLTC insert are determined by the age of the equipment.
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Contact wear can be evaluated by measuring the transition resistors.
Contact wear can be evaluated by measuring the transition resistors.
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It is safe to operate the OLTC without verifying the sealing condition of the suction pipe.
It is safe to operate the OLTC without verifying the sealing condition of the suction pipe.
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The main function of cleaning the oil compartment is to enhance lubrication for the gear mechanism.
The main function of cleaning the oil compartment is to enhance lubrication for the gear mechanism.
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Replacing the contact rollers is not necessary during regular maintenance of the OLTC insert.
Replacing the contact rollers is not necessary during regular maintenance of the OLTC insert.
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The OLTC insert can be reinstalled without reinserting the suction pipe first.
The OLTC insert can be reinstalled without reinserting the suction pipe first.
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The change-over selector is switched off during the withdrawal of the OLTC insert.
The change-over selector is switched off during the withdrawal of the OLTC insert.
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The OLTC insert should be exposed to air for no more than 12 hours.
The OLTC insert should be exposed to air for no more than 12 hours.
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An oil pump is necessary for the ease of oil change procedures.
An oil pump is necessary for the ease of oil change procedures.
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The determination of contact wear takes place with the change-over selector.
The determination of contact wear takes place with the change-over selector.
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Miscellaneous brushes and rags are not essential for cleaning during the inspection.
Miscellaneous brushes and rags are not essential for cleaning during the inspection.
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The maximum oil filling quantity for the OLTC insert is 320 litres.
The maximum oil filling quantity for the OLTC insert is 320 litres.
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Cleaning the oil compartment does not require specific brushes.
Cleaning the oil compartment does not require specific brushes.
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Tools required for cleaning include only standard brushes.
Tools required for cleaning include only standard brushes.
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Care and cleanliness are secondary priorities during the inspection process.
Care and cleanliness are secondary priorities during the inspection process.
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Water content of oil in on-load tap changers is required to be measured by the Karl Fischer method.
Water content of oil in on-load tap changers is required to be measured by the Karl Fischer method.
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The normal interval for inspecting a transformer with an oil filter is recommended to be every 5 to 6 years.
The normal interval for inspecting a transformer with an oil filter is recommended to be every 5 to 6 years.
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IEC Publication 422 provides standards related to the dielectric strength of oil under test conditions.
IEC Publication 422 provides standards related to the dielectric strength of oil under test conditions.
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The recommended maximum dielectric strength for tap changer oil is 35 kV/2.5 mm.
The recommended maximum dielectric strength for tap changer oil is 35 kV/2.5 mm.
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DIN 57 370 Teil 1 is cited for guidelines on measuring the temperature of the oil during sample-taking.
DIN 57 370 Teil 1 is cited for guidelines on measuring the temperature of the oil during sample-taking.
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The number of tap change operations does not influence the recommended inspection intervals.
The number of tap change operations does not influence the recommended inspection intervals.
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It is suggested that inspections of tap changing equipment be conducted by untrained personnel.
It is suggested that inspections of tap changing equipment be conducted by untrained personnel.
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An inspection report must be submitted to ensure proper future recommendations.
An inspection report must be submitted to ensure proper future recommendations.
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The OLTC insert is one of the basic parts of the OLTC.
The OLTC insert is one of the basic parts of the OLTC.
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The change-over selector is available in all OLTC types.
The change-over selector is available in all OLTC types.
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The oil compartment is not subject to inspection during maintenance of the OLTC.
The oil compartment is not subject to inspection during maintenance of the OLTC.
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The tap changer head is one of the basic parts marked for inspection.
The tap changer head is one of the basic parts marked for inspection.
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The OLTC can operate without the separate change-over selector.
The OLTC can operate without the separate change-over selector.
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The basic parts of the OLTC are represented in black and white in the inspection guide.
The basic parts of the OLTC are represented in black and white in the inspection guide.
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The model H Ill 400A—145 is available without a change-over selector.
The model H Ill 400A—145 is available without a change-over selector.
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The delivery date for the modified components is noted as 6/89.
The delivery date for the modified components is noted as 6/89.
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H I 400 A—123 with a built-in component is marked as 'no. 2' with a value of 3.6.
H I 400 A—123 with a built-in component is marked as 'no. 2' with a value of 3.6.
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The configuration H II 400A—40/76 is listed as having a built-in feature, and it records a value of 10.6.
The configuration H II 400A—40/76 is listed as having a built-in feature, and it records a value of 10.6.
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There are two types of configurations mentioned for H Ill 400A—123 one with and one without a built-in feature.
There are two types of configurations mentioned for H Ill 400A—123 one with and one without a built-in feature.
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All models listed with built-in features have been designated with the same value of 36/71.
All models listed with built-in features have been designated with the same value of 36/71.
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The term 'separatly attached' is used within the context of the H I 400A—145 configuration.
The term 'separatly attached' is used within the context of the H I 400A—145 configuration.
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The H I 400Y model is depicted without any specific features marked.
The H I 400Y model is depicted without any specific features marked.
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The document details a total of five distinct configurations for the H 111 models.
The document details a total of five distinct configurations for the H 111 models.
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The phrase 'without change-over selector' appears only for the model H 111 400 A.
The phrase 'without change-over selector' appears only for the model H 111 400 A.
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Study Notes
OLTC Installation and Adjustment
- Position the hanging OLTC insert correctly for smooth switching between stationary change-over selector contacts.
- OLTCs can either have a built-in change-over selector or a separately attached one, impacting the positioning during installation.
Adjustment Position Setup
- OLTC insert must be set to the adjustment position using the operating key.
- For units with a built-in selector, move the change-over contacts counterclockwise to reach the switched position.
- Detach the operating key to reinsert the suction pipe and center the OLTC insert in the oil compartment.
Gear Mechanism Installation
- Reinstall the gear mechanism in the reverse order of its removal.
- Gear mechanism needs to be set to the adjustment position using the position indicator and red gear marks.
- Securely attach the gear mechanism supporting plate with five M8 x 30 screws at a maximum torque of 14 Nm, using lock tabs for security.
Oil Filling Procedure
- Fill the oil compartment with new transformer oil to the gear mechanism support plate level.
- Ensure O-ring gasket is intact, replace if necessary before covering the tap changer head.
- Attach the head cover with 24 M10 x 35 bolts, maintaining a maximum torque of 35 Nm and securing with spring washers.
Bleeding and Safety Checks
- Open stop valve between oil conservator tank and tap changer head for proper oil flow.
- Bleed the tap changer head and suction pipe to eliminate air pockets before operation.
- Ensure that the transformer and connections are undamaged and cannot be energized during testing.
Drive Shaft Assembly
- Couple horizontal drive shaft to the tap change indication wheel for synchronization.
- The MA 8 motor drive's indication wheel is divided into 30 sections, each correlating to a full rotation.
- Ensure that position indications of motor drive and tap changer are equal for symmetrical coupling during adjustment.
Miscellaneous Checks
- Conduct a test on the protective relay, ensuring that all circuit breakers function correctly.
- Equipment must be safe to energize post-checks, and fire-extinguishing systems must be operational before the relay checks.
- Contact authorized service representatives for serious tap changer or motor drive issues that cannot be repaired on-site.
Functional Principle of OLTC
- On-load tap changers (OLTC) are vital components in transformers, allowing adjustments to voltage levels while the transformer is energized.
- OLTC aids in maintaining efficient operation and reliability of electrical systems.
Designation of OLTC Models
- OLTC models are designated according to their specifications, including current ratings and voltage capacities.
- Common models include H I 400 Y, H I I 400 A, H I I 400 A-123, and H I I 400 A-145.
Principal Parts of the OLTC
- Essential components include:
- Tap changer head
- Oil compartment
- OLTC insert
- Change-over selector (specific to certain models)
Inspection Intervals
- Regular inspections recommended every 6 to 7 years or after a specified number of operation cycles to ensure functionality.
- Key checks include dielectric strength and water content of oil, adhering to standards like IEC Publication 422 and DIN 57 370.
Summary of Inspection Works
- Inspections involve:
- Removal and reinstallation of the OLTC insert
- Cleaning of the oil compartment and OLTC components
- Oil change and checking for contact wear and transition resistors
Preparations for Inspection
- Equipment needed includes:
- Empty vessels for dirty oil disposal
- Clean oil for refilling
- Oil pump for easy oil change
- Cleaning brushes and rags
- Work should maintain strict cleanliness to avoid contamination.
Removing the OLTC Insert
- Steps for removal include:
- Taking off the tap changer head cover
- Detaching the gear mechanism
- Withdrawing the suction pipe
- Turning off the change-over selector and operational key
Cleaning Procedures
- Cleaning focuses on:
- Oil compartment and OLTC insert
- Suction pipe to ensure proper flow and functionality
Inspection of the OLTC Insert
- Inspections include:
- Measuring transition resistors for integrity
- Assessing contact wear for operational efficiency
Replacing the Contact Rollers
- Replacement entails:
- Removing old contact rollers
- Installing new rollers to maintain voltage regulation effectiveness
Reinstalling the OLTC Insert
- Reinstallation involves:
- Carefully reinserting the OLTC insert and suction pipe
- Reinstalling the gear mechanism to re-establish connectivity
Oil Filling
- Oil filling quantities vary by model, ensuring the correct amount is used for optimal performance.
- Essential parameters include rated voltage levels, current specifications, and recommended oil quality standards.
Key Inspection Data
- Regular monitoring is critical:
- The oil's dielectric strength and water content should be less than 40 ppm and above 30 kV/2.5 mm for reliability.
- Inspections are performed in accordance with established standards and documented to ensure safety and compliance.
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Description
This quiz focuses on the operational positioning of On-Load Tap Changers (OLTC) in transformers, specifically regarding built-in and separately attached change-over selectors. It provides insights on ensuring smooth functionality of switching elements with stationary change-over selector contacts. Test your understanding of OLTC mechanisms and their alignment procedures.
