To stay competitive, companies are forced to improve their products continuously. Field data is a source of information that shows the actual performance of products during operation, and that information can be used to clarify the items in need of improvements. This master thesis aims at identifying the set of field data that is required for dependability improvements and to develop a working procedure that enables increased utilization of the field data in order to make cost-effective design improvements. To achieve this, a 12-step model called the Design Improvement Cycle (DIC) was developed and tested in a single case study. The field data need was identified using a top-down method and was included as a part of the DIC. Testing of the model showed that it was practicable and each step could be carried through, even though the last steps only could be tested hypothetically during discussions with concerned personnel. The model implied a working procedure that should be aimed at, according to personnel with competence within the subject. As the DIC appeared to be very flexible it should be possible to use within several areas. It was discovered that field data was not a sufficient source of information to support design improvements but it could be used to indicate which items that should be focused on during further investigations. The quality of the field data had a big impact on the analysis possibilities and to point out which data quality issues that had to be amended to make the data more useful, the data need for dependability improvements could be used.

This thesis investigates problematic cases in AC substation grounding system design. Particularly, the grounding design for substations that are built on high resistivity soil is considered. Here, possible physical rectification schemes are introduced and compared for their effectiveness from safety and cost efficiency perspectives. For this comparison, the CYMGRD program (a finite element analysis tool for AC substation grounding) is used for detailed analysis of the various schemes. An additional computer program is developed to implement the formulations of the related AC substation standards (IEEE, IEE, and Turkish National Regulations). The output of this program is compared with the finite element analysis of the high-resistivity-soil rectification schemes to investigate the validity of the formulations in these standards.

<p>To stay competitive, companies are forced to improve their products continuously. Field data is a source of information that shows the actual performance of products during operation, and that information can be used to clarify the items in need of improvements. This master thesis aims at identifying the set of field data that is required for dependability improvements and to develop a working procedure that enables increased utilization of the field data in order to make cost-effective design improvements. To achieve this, a 12-step model called the Design Improvement Cycle (DIC) was developed and tested in a single case study. The field data need was identified using a top-down method and was included as a part of the DIC.</p><p>Testing of the model showed that it was practicable and each step could be carried through, even though the last steps only could be tested hypothetically during discussions with concerned personnel. The model implied a working procedure that should be aimed at, according to personnel with competence within the subject. As the DIC appeared to be very flexible it should be possible to use within several areas. It was discovered that field data was not a sufficient source of information to support design improvements but it could be used to indicate which items that should be focused on during further investigations. The quality of the field data had a big impact on the analysis possibilities and to point out which data quality issues that had to be amended to make the data more useful, the data need for dependability improvements could be used.</p>