The aims of the following project has beento make a proposition how to create aspecific kind of transformer. Thefollowing report evaluates the differentimportant variables and contains asuggestion for a possible design. Intheory it's an ordinary transformer that'ssuppose to transform electrical effect toa high voltage line. The design of thetransformer is using an already existingCurrent transformer design and is adjustedto work for it's specific purpose. Theproject also contains the developing of atransformer simulation model that will beused to evaluate and optimize thedimensions of the resulting transformer..

The aims of the following project has beento make a proposition how to create aspecific kind of transformer. Thefollowing report evaluates the differentimportant variables and contains asuggestion for a possible design. Intheory it's an ordinary transformer that'ssuppose to transform electrical effect toa high voltage line. The design of thetransformer is using an already existingCurrent transformer design and is adjustedto work for it's specific purpose. Theproject also contains the developing of atransformer simulation model that will beused to evaluate and optimize thedimensions of the resulting transformer..

Historically transformers with system earth equipment have been modeled as open circuits in zero sequence. This approximation has been satisfying, but lately it has been discovered that equipment on one side of the transformer have responded to faults that occurred at the other side. Most of these problems took place when the majority of the system on the secondary side of the transformer contained cables. These findings have led to questioning whether or not the former model of the transformer in zero sequence is correct. This report investigates if it is necessary to represent the transformer in zero sequence in another way than it is usually done today.

This master thesis has been performed at Vattenfall Power Consultant in Gothenburg and Trollhättan for Vattenfall Vattenkraft. In this report vacuum circuit breaker in small-scale hydropower stations with the rated power 4 MVA and below has been studied. Models of the stations are modeled and analyzed in PSCAD/EMTDC to study the high voltage transients that are created after current chopping with vacuum circuit breaker. Vacuum circuit breaker may chop the current before it reaches zero value, which means that high voltage transients can be created. The equipment of the stations can be destroyed by high voltage transients.The purpose of this thesis is to examine the use of vacuum circuit breaker in small-scale hydropower stations and the risk for high voltage transients from current chopping.According to the results there is a risk of high voltage transients after current chopping with small synchronous generators in stations with the operating voltages 0.4 kV and 3.6 kV.

This report is a degree project performed at Freudenberg Household Products AB, (FHP). The degree project comprises measurement and analysis of the power net at FHP Basproduction. The content is divided between one theory-part, one document- part with measurements and also conclusions and a list of measures to be taken. During the project the purpose and restriction change from a quality investigation to only concentrate on harmonics and finding the reason why they exist, and also to find a solution to the problem with harmonics. The measurements shows that the power net contains harmonics of different order and intensity.

Problem StatementAfter the hurricane Gudrun in January 2005 EON Elnät Sverige AB started the project KRAFTTAG, were 17,000 km of the airborne power grid shall be replaced with cables underground. The transformers in the airborne power grid shall be dismounted, renovated if necessary and then conveyed to stations, of type kiosk.Additional new transformers, more than planned, have been bought. This is due to the dysfunctional transformer flow from the demolished power supply to projects, were the new power supply is built, the general picture is complicated, since the reconstruction involves other companies and many employees at E.ON.PurposeThe purpose of this master thesis is to map and understand the existing transformer flow. The objective is to make a recommendation on how to increase the level of E.ON? s transformer recycling.Methodthe authors have worked with a system approach, including both qualitative and quantitative data.

The majority of all power cuts that affects individuals and communities are caused by earth faults on the power transmission lines at 10kV and 20kV level [1]. If these power cuts could be eliminated, less disturbances and interrupts would lead to large amounts of money savings.Swedish Neutral has developed such a protection system. When an earth fault occurs power is injected into the neutral point of the transformer. The RCC (Residual Current Compensation) protection calculates a compensation current exactly 180 degrees out of phase to the fault current. Doing this, the voltage at the fault location becomes very close to zero, without affecting the power transmission.The protection system can only compensate automatically for the fundamental frequency (50Hz), and manually for the 3rd, 5th, 7th and 9th harmonics.

The transformer is one of the most common and most important electric machines for power companies. Cost of investment and the economic worth of a transformer are counted in millions of SEK. Because of that, proper maintenance actions that may lead to longer technical life time should be the aim in all situations.The aim with the report was to perform transformer diagnosis by dissolved gas analysis on Umeå Energi AB´s power transformers and a risk assessment. The report should also contribute to longer life time for the transformers.Oil samples were taken from each transformer two times. The first sample in summer 2013 and the second in April 2014.

As break downs of production transformers are costly and often result in long outages it is essential for reliability of operation that the transformers are manufactured to be robust. The aim of this M.Sc. thesis is to investigate if deviations should be made from the standard IEC 60076 ? Power Transformers in order to describe a robust large power transformer for procurement.The investigation has been conducted in three stages. In the first stage a definition of the term robust was developed in consultation with the client Vattenfall Vattenkraft.

Renewable energy and the charging of electrical vehicles will increase in the future. Therefore the risk of outages is also increasing, partly because renewable energy is intermittent and the production amount can change fast. Charging electrical vehicles is often demanding high effect in short time, which could make faults occur. It takes more advanced technology to short the outage time. Today Övik Energi has high reliability in the power grid, but in order to maintain the reliability, it is time to prevent problems that can occur in the future. This thesis has presented a suggestion for the placement of fault detectors Protrol IPS2, in which a total of four detectors is proposed.

The purpose of this master thesis is to present a model that illuminates the important factors when deriving technical information from market data within a company. For companies to be able to become and stay competitive in the market, product quality is an important factor. Whilst good product quality leads to customer satisfaction and loyalty, lack of quality brings costs in service and replacements. To improve product quality, the developers need information and knowledge about what quality issues affect existing products. Most companies gather data from market about known issues, but in order eliminate known quality issues in new products; this data has to be transformed into information and knowledge.

Normally the operational amplifier is used as a component in active filter design. The goal for future components in filter design is large bandwith and the use of low supply voltages. The use of current-mode instead of voltage-mode circuits gets a step closer to the required performance. A component that use current as the signal conveying part is the current conveyor. In this report a comparative study between two current conveyor structures of second generation (CCII) is performed.

To measure losses in a transformer with today?s methods is either slow or insecure. There s a new method developed by Alstom that hasn't been actualize in to a test-system and that has been the assignment in this project. The idea is built on a switched system and a CLR- circuit in the resonant frequency. The test-system has a calculated power-loss that make the efficiency to be as high as 99,8% and in reality over 95%.

A current conveyor is an active building block that can be used to implement most active and passive components. It differs from the operation amplifier in that it uses current instead of voltage. The current conveyor also has significantly higher voltage gain over a broader frequency range. To simplify the construction of analogue circuits and increase the construction efficiency it is desirable to use a top-down methodology. This means that the whole system is partitioned into a hierarchy of subsystems.

A study was made to evaluate how current measurementscould help to determine how particles from fish farms are dispersed. During sixweeks of the summer 2012, two different current measurements were conducted.One of them consisted of measurements each fifth minute at 5 m and 15 m atthree locations for 14-16 days each. The other consisted of profilemeasurements at each location at four times during the period of six weeks. Forthe current measurements two instruments (model RCM 9) were used. A two weekmeasurement can give enough data to make an evaluation of how the currents at alocation will transport litter from a fish farm.