MR Oil Filter Maintenance Quiz

Questions and Answers

What is the recommended action when the tap changer has exceeded 800,000 switching operations?

It should be inspected but not replaced.

It should be inspected by untrained personnel.

It should be immediately replaced. (correct)

It may be inspected and replaced if needed.

What is the suggested frequency for inspecting the MR oil filter unit?

Once a year at minimum.

Regular intervals to maintain reliability. (correct)

Only when faults are reported.

Every month regardless of usage.

What is the consequence of not having inspections carried out by MR personnel?

A report is requested to supplement inspection data. (correct)

Immediate shutdown of the unit.

No consequences; other personnel can handle it.

The unit will operate at a lower efficiency.

In which climate conditions is monitoring of insulating oils especially recommended?

Tropical or subtropical climates. Signup and view all the answers

What can potentially extend the inspection intervals of the MR oil filter unit?

Filtering the switching oil effectively. Signup and view all the answers

What is the immediate recommendation for operations exceeding 15,000 per year?

Employ a stationary oil filter unit type 51. Signup and view all the answers

Who should ideally carry out the inspections for the MR oil filter unit?

Qualified and MR-trained personnel. Signup and view all the answers

What type of filter insert is recommended for the stationary oil filter unit type 51?

A paper filter insert. Signup and view all the answers

What is the maximum torque specified for attaching the inner screening rings?

9 Nm Signup and view all the answers

How many hexagon socket-head screws are used to attach each inner screening ring?

3 screws Signup and view all the answers

What should be removed before cleaning the switching tube?

Bottom bearing Signup and view all the answers

Which type of screws are used for fixing the bottom bearing?

M8 x 20 screws Signup and view all the answers

What is the first step in the reinstallation of the inner screening rings?

Fix the inner screening rings provisionally to the switching tube Signup and view all the answers

What must be done after unscrewing the fixing screws of the bottom bearing?

Remove the bottom bearing from the switching tube Signup and view all the answers

What is necessary for working with tap changers of types V 111 350 Y or V 350 since 06/95?

Follow section 4.3.2.1 Signup and view all the answers

What should not be lost when removing the bottom bearing for certain tap changers?

Dished washers Signup and view all the answers

What is the water content limit for transformer oil in the on-load tap changer type VI200Y?

< 40 ppm Signup and view all the answers

Which on-load tap changer type requires an inspection every 2 years?

V II 250 D Signup and view all the answers

What is the dielectric strength requirement for transformer oil in on-load tap changers?

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

What is the maximum number of tap changer operations allowed without an MR oil filter unit for type VII500Y?

100,000 Signup and view all the answers

What is the effect of disregarding the recommended inspection intervals?

Risk of trouble-free operation Signup and view all the answers

What is the recommended first inspection time frame for the on-load tap changer type VI350 Y?

6 - 7 years Signup and view all the answers

Which method is used to measure water content in transformer oil?

Karl-Fischer method Signup and view all the answers

For the tap changer type VIII400Y, what is the maximum number of operations allowed with an MR oil filter unit?

140,000 Signup and view all the answers

What type of arrangement for an on-load tap changer allows for further inspections every 4 years without an MR oil filter unit?

At the line end of delta winding Signup and view all the answers

How often should type VII400D be inspected if it has an MR oil filter unit?

6 - 7 years Signup and view all the answers

What is the maximum torque specified for the M6 screws during the removal of the switching elements?

9 Nm Signup and view all the answers

How many self-locking screws are used to secure each bottom bearing?

4 screws Signup and view all the answers

During the assembly of the potential plate, what is the order of components to be installed?

Tensioning disks, potential plate, lock tab, screw M8 x 25 Signup and view all the answers

How are the screws securing the upper screening ring of the lower switching element described?

6 screws M5 x 8/w.s. 8. Signup and view all the answers

What component is not specified to be removed with the main switching contact bearing support?

Screening ring Signup and view all the answers

What should not be lost during the removal process of the switching elements?

Tensioning disks Signup and view all the answers

Which screws are necessary to unlock and loosen at the main switching contact bearing support?

4 screws M6 x 30 Signup and view all the answers

Which component has a cylindrical design and is specified by an M size?

Cylindrical pin Signup and view all the answers

What is the length in millimeters of the head screw specified as M6?

20 mm Signup and view all the answers

Which of the following parts is associated with pressure springs?

Pressure spring for main contact lever Signup and view all the answers

What type of component does the term 'circlip' refer to?

A locking mechanism Signup and view all the answers

Which specification indicates a pitch design feature?

0- pitch hand 12-pitch design Signup and view all the answers

Which on-load tap changer model is referenced in the content?

Type V Signup and view all the answers

What is the designation of the pressure spring designed for the contact roller?

550 105 Signup and view all the answers

Which is the correct part number for the lock nut specified for M6?

453 977 Signup and view all the answers

Which part is classified as a cable component in the content?

Cable socket with pin Signup and view all the answers

Which part number corresponds to a lock nut for M5?

453 981 Signup and view all the answers

The gearing can be removed by lifting it out after loosening the guard plate.

True Signup and view all the answers

The coupling piece to the upper gear unit has 8 screws M6 that need to be loosened.

False Signup and view all the answers

The drive shaft must always be completely removed to allow access to the gearing.

False Signup and view all the answers

It is important to count all small parts during the disassembly process to ensure that nothing is lost.

True Signup and view all the answers

Two bolts M10 x 35/w.s.17 need to be unscrewed to remove the tap changer cover.

False Signup and view all the answers

The energy accumulator spring system requires replacement after every 100,000 operations.

False Signup and view all the answers

Spring washers must be taken care of not to lose during the removal of the gearing.

True Signup and view all the answers

The energy accumulator spring system is fixed to the tap changer cover by 5 screws M8.

True Signup and view all the answers

The lift height for the tap changer insert listed as Vil 500Y is 1750 mm.

True Signup and view all the answers

The required oil capacity for the tap changer type Vii 350D is 145 litres.

False Signup and view all the answers

The inspection procedure necessitates cleaning both the oil conservator and the oil compartment of the tap changer.

True Signup and view all the answers

Changing the switching oil is not required during a tap changer inspection.

False Signup and view all the answers

The tap changer model VI 200Y has an inspection frequency of every three years.

False Signup and view all the answers

Determining contact wear is included in the scope of work for the tap changer inspection.

True Signup and view all the answers

The oil compartment must have used oil emptied before the cleaning process begins.

True Signup and view all the answers

Vil 200 has a lifting height of 800 mm without the operating key attached.

False Signup and view all the answers

The maximum torque for fixing the bottom bearing is 9 Nm.

False Signup and view all the answers

After flushing the inside of the switching tube, a thorough visual check is required.

True Signup and view all the answers

Dished washers are used with M5 screws for fixing screening rings.

False Signup and view all the answers

A brush of 140 mm diameter can be used to remove carbon deposits from the switching tube surface.

True Signup and view all the answers

The maximum torque for self-locking screws securing the inner screening rings is 10 Nm.

False Signup and view all the answers

The removal order of the inner screening rings does not need to be noted.

False Signup and view all the answers

New screws must be used for reassembly of the hexagon socket-head screws after removal.

True Signup and view all the answers

Flushing with transformer oil is recommended to prepare the inside of the switching tube for assembly.

True Signup and view all the answers

The complete set of contact rollers should be replaced only if the minimum contact roller diameter has been reached during inspection.

False Signup and view all the answers

Checking the spring movement of the contact rollers is only necessary for the main contact.

False Signup and view all the answers

Inspection of the contact rollers should be performed after every 100,000 switching operations.

False Signup and view all the answers

The contact rollers are to be inspected for smooth spring operation as part of regular maintenance.

True Signup and view all the answers

The minimum contact diameter for the complete switching contact V 350 is 22.0 mm.

True Signup and view all the answers

Replacement of contact rollers should be done in isolation, without considering other switching elements.

False Signup and view all the answers

Inspection of the spring movement of contact rollers is unnecessary if they appear visually intact.

False Signup and view all the answers

The torque specified for securing self-locking hexagon socket-head screws M6 is 10 Nm.

False Signup and view all the answers

The contact diameter for the complete transition contact Vv 200 on the left is indicated as 20.0 mm.

True Signup and view all the answers

The maximum number of contacts in the circle for the complete switching contact of type V 500 is 14.

False Signup and view all the answers

The contact diameter of the complete switching contact for type V 1350 is 22.0 mm.

True Signup and view all the answers

The diameter values for contact rollers are only specified when the contact is replaced.

False Signup and view all the answers

The complete transition contact for type V 350 has a contact code of 086 063.

False Signup and view all the answers

The contact diameter for the complete switching contact V 500 is 220 mm.

False Signup and view all the answers

A torque of 5 Nm is sufficient to secure the M6 screws of the contact roller bearing plates.

False Signup and view all the answers

Self-locking hexagon socket-head screws M6 are used at the contact roller bearing bushings.

True Signup and view all the answers

Study Notes

Maintenance and Inspection of Oil Filter Units and Tap Changers

Regular maintenance of MR oil filter units is essential for maintaining high operating reliability.
Tap changer inserts and gearings need replacement after 800,000 switching operations.
Qualified personnel should perform inspections, ideally within one day, if well-prepared.
Use of stationary oil filter unit type 51 with a paper filter is recommended if operations exceed 15,000 per year.
Insulating oils in transformers should be monitored per manufacturer guidelines to maintain dielectric properties.
In humid, tropical climates, combined filter inserts are advised to avoid dielectric property degradation.

Oil Testing and Monitoring

Key water content thresholds for transformer oil testing:
- V III 200 Y, V I N 350 Y, V I I I 500 Y: < 40 ppm
- V I I 200 D, V I N 350 D, V I I I 500 D: < 30 ppm
Required dielectric strength for transformer oils:
- V III 200 Y, V I N 350 Y, V I I I 500 Y: > 30 kV/2.5 mm
- V I I 200 D, V I N 350 D, V I I I 500 D: > 40 kV/2.5 mm

Inspection Intervals

Inspection intervals based on tap changer type and operation levels:
- For types V I I 200 Y, V I I 350 Y, V I I 500 Y:
  - First inspection: 6-7 years
  - Further inspections: 6-7 years (with/without MR oil filter unit)
- For other types (e.g., V I I I 200 D, V I I I 250 D, etc.):
  - First inspection: 2 years
  - Further inspections: 4 years (without MR oil filter unit), 6-7 years (with MR oil filter unit)

Assembly Procedures

Detailed steps for reinstallation of inner screening rings include:
- Provisional fixing of inner screening rings with screws.
- Securely attaching rings with hexagon socket-head screws and dished washers.
Disassembly steps vary by tap changer type but generally involve loosening multiple screws and numbering switching elements for reassembly.

Risk and Compliance

Ignoring inspection intervals can jeopardize the trouble-free operation of the system.
Proper documentation and reporting are required if non-MR personnel conduct inspections.

Parts and Specifications

List of parts for tap changers is provided, including specific screw types and sizes required during reinstallation.
Emphasis on securing components properly to ensure functionality and safety.

Key Caution

Strict adherence to maintenance routines and documentation is critical to operational integrity and safety.

Inspection Preparation

Inspection includes tap changer insert removal and reinstallation, cleaning of oil compartments, and oil changes.
Requires auxiliary equipment for performing inspections.

Required Tools and Equipment

Empty vessels for used oil and new transformer oil.
Various dimensions of equipment, e.g., V i 200 (800/950 mm) and V i l l 500D (2000/2200 mm).

Oil and Contact Checks

Switching oil must be changed during inspections.
Check the tap changer oil compartment and tap changer insert for quality and wear.
Determine contact wear to assess maintenance needs.

Removal Procedures

Remove guard plate and loosen various screws without losing spring washers.
Avoid dropping parts into the oil compartment as it may damage the transformer.
Count and retain all small parts, including bolts, nuts, and lock tabs during disassembly.

Energy Accumulator and Gearing

Energy accumulator spring system must be handled carefully to avoid damage.
The switching tube contains grooves for washer placement; removing washers is crucial for maintenance.

Cleaning Protocols

Switch tube cleaned by thorough flushing with transformer oil; debris removal is essential.
Ensure proper reinstallation of parts to maintain insulating properties.

Contact Roller Maintenance

Inspect smooth operation of contact roller springs; check all contact types.
Replacement is required when roller diameter falls below minimum thresholds.

Contact Specifications

Specifications for contact sizes include:
- V 350 complete switching contact: new diameter 22.0 mm, minimum 17.0 mm.
- V 200 complete transition contact: new diameter 22.0 mm, minimum 16.0 mm.
- V 500 complete switching contact: new diameter 22.0 mm, minimum 17.0 mm.

Torque and Security Checks

Check secure fit of screws M6 at 8 Nm torque for contact roller bearing.
During inspections of specific tap changer types, ensure proper torque procedure adherence.

Safety Notes

Pay attention to the installation order of the potential plate and internal components.
Use new self-locking screws for reassembly to ensure component integrity.

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Description

Test your knowledge on the maintenance of MR oil filters and the importance of regular inspections. This quiz covers the operating instructions related to tap changers and filtering of switching oil. Ideal for professionals looking to ensure reliability in operations.