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.

As a part of Göteborg Energi?s work towards a smarter electric grid, the company has chosen to investigate the possibilities of automation in their middle voltage grid. In Europe, there are example cases where these technologies already are installed which many articles on the CIRED conference 2011 proved. Netcontrol Oy in Finland has, together with Tekla, created an automated SCADA system that Vattenfall in Finland today uses. The grid mainly consists of 10 kV open loop fed city grid and this automation is mainly designed for this type of grid.

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.

This paper deals with the development of scientific geography during Antiquity from its mythical background before the seventh century BC to Claudius Ptolemy during the second century AD. The main focus is on questions concerning the shape of the earth, its place in the universe, size and mapping of the earth. Already before 400 BC, the idea of the earth as a globe was firmly estabished. During classical time, Aristotle used empirical and rational arguments to prove that the earth was a sphere and that it was situated motionless in the center of the universe. In the third century BC, the first reasonably correct measurements of the circumference of the earth was carried out by Eratosthenes.

This master of science thesis is focusing on how the fault handling on hardware connected toa control unit on a Scania vehicle is working. To the hardware counts buttons levers, sensorsand CAN. The work has been concentrated upon how the fault handling is working and if it ispossible to find any new fault modes.The control unit that has been studied is called the Coordinator and is the core in Scanias threenetworks of control units. The Coordinators work is to transmit messages between the threenetworks and to process signals from buttons, levers and sensors. The values is then usedinternally or is sent to other control units on the CAN networks.

Earth science is a dynamic system science that explores the structures and processes of the earth. Knowledge about the earth is important for citizens since the science is a vital part in the sustainable development of the society. Without good basic knowledge the citizens don?t have the possibility to anticipate in the questions and decision-making that concerns e.g. anthropogenic climate change. In the Swedish school system earth science is not an independent subject until academically studies at the University?s.

Earth science is a dynamic system science that explores the structures and processes of the earth. Knowledge about the earth is important for citizens since the science is a vital part in the sustainable development of the society. Without good basic knowledge the citizens don?t have the possibility to anticipate in the questions and decision-making that concerns e.g. anthropogenic climate change. In the Swedish school system earth science is not an independent subject until academically studies at the University?s.

With rising energy prices and the threat of climate change, energy costs and energy savings havebecome a central and important part in building. Therefore it is interesting to explore different andnon-conventional methods of energy conservation. Building Earth sheltered houses is such a method.Earth provides good insulation and provides the ability to both reduce the total heating needs and toreduce the maximum power demand. The aim of this study was to construct a house in Malmö and seeif Earth sheltered houses can be a cost effective alternative for the construction of sustainable andenergy-efficient houses.Previous studies have shown that Earth sheltered houses have reduced their power requirement with upto 25% and their use of energy with 10%. Numerical calculations in Comsol Multiphysic 4.2, wasperformed on a house with different degrees of earth covering.

Because of increasing demand of power on Malmbanan the capacity of the existing wires which supply the trains must be increased. This increases the stress on the existing poles and for this reason the system for supplying the loads along the railway is to be removed from the poles and be replaced by some other system. This thesis is a study on a two-level low voltage (1 kV and 0.4 kV) electrical system with the aim to investigate if it can be an alternative to the system used today taking into account the voltages, fault currents and costs.In this thesis the following tasks have been performed:? Gathering of data? Description of basic theory? Loadow and fault current calculations of the system with MATLAB? Life Cycle Cost estimate of the system? Analysis and conclusions from the resultsThe results show that the new system can be an alternative to replace today's system. The simulations and calculations show that the voltage drop is at an acceptable level and that the fault currents are large enough to supply a safe disconnection if a fault occurs at the far end of the system..

The purpose of this project is to analyze earthing systems for houses. By practical measurements and theoretical analyzes consequences of possible faults, that can occur within the facility and in the low-voltage distribution network, is illustrated.  The reason for this project is that nowadays one has to arrange with a main equipotential bonding system for buildings. Apart from that, if necessary, bathrooms must be provided with a supplementary equipotential bonding system.The practical measurements verify that potential differences in facilities may be due to voltage drops in the PEN conductor between the origin of the electrical installation and the power transformer.Based on the theoretical analyzes of possible faults, it is considered that the requirement for  supplementary equipotential bonding systems for bathrooms in most cases can be questioned, when basic insulation, fault protection, residual current devise and main equipotential bonding system already provides an adequate level of protection.A PEN conductor loss may result in a situation where metallic parts attached to the equipotential bonding system starts working as earth electrodes. Equipotential bonding system may also increase the incidence of stray currents. If TN-C-S systems is provided with a local connection to earth a redundant system against PEN conductor loss is obtained.

The purpose of this thesis work was to develop an automatic fault detection system for surveillance of bearing temperature in hydropower turbines. The parameters used except the bearing temperature were cooling water temperature and cooling water flow. A simple static model based on data sampled every minute was developed to estimate the bearing temperature. Then a detector for detection of change in bearing temperature based on the CUSUM-algorithm was designed. Since the amount of data was very small the developed model was too uncertain to be used in a working system.The designed fault detection system showed to work well for the available data.

With background in the rapidly growing need to find solutions for sustainable energy production and the increasing interest for wind power, this report was written. With take-off point from the wind power plant Big Glenn, which has been built in the harbour of Gothenburg, a model of the adjacent power grid has been created in Simulink/SimPowerSystems. Parameters for the power grid and its components has been provided by Göteborg Energi Nät, that has also been the supplier of measurement data of produced power, the power need from loads in the vicinity, voltage levels, current values and also the variation of power factor at the wind power plant.The SimPowerSystems model has been used to perform simulations of power flow in the grid. These simulated values have then been compared to the measured values to verify the functionality of the model. Further, the model has been used to perform simulations of a grid fault, which causes a voltage drop.

With background in the rapidly growing need to find solutions for sustainable energy production and the increasing interest for wind power, this report was written. With take-off point from the wind power plant Big Glenn, which has been built in the harbour of Gothenburg, a model of the adjacent power grid has been created in Simulink/SimPowerSystems. Parameters for the power grid and its components has been provided by Göteborg Energi Nät, that has also been the supplier of measurement data of produced power, the power need from loads in the vicinity, voltage levels, current values and also the variation of power factor at the wind power plant.The SimPowerSystems model has been used to perform simulations of power flow in the grid. These simulated values have then been compared to the measured values to verify the functionality of the model. Further, the model has been used to perform simulations of a grid fault, which causes a voltage drop.

Denna rapport handlar om Övervakning i en IT miljö som täcker både nätverk och system. Denna rapport inriktar sig på Fault Management och Performance Management..

The use of earth bricks in Scanian building traditionThe present work is concerned with the manufacturing and use of earth bricks inbuilt heritage in the south Swedish province of Scania. The first part of the studyprovides a thorough description of the traditional use and manufacturing of earthbricks based on relevant literature, archive material as well as interviews withinformants. This forms a basis for the second part of the study in which practicalexperiments on and tests with earth bricks where carried out. This involved themaking of traditional earth bricks of different composition. The new handmadebricks were compared with industrially produced bricks (extrusion bricks) and oldhandmade bricks.