<p>After extensive research during the last decades extruded polymeric insulation is now becoming an alternative to the traditional oil-paper systems for high voltage DC (HVDC) cables. Durability is of great importance for power cables, and the main purpose of this work has been to increase the knowledge of factors controlling the endurance of an extruded polymeric insulation under HVDC conditions. The effect of electrical and thermal ageing on electrical properties like space change accumulation, DC breakdown strength and electrical tree initiation has been investigated and related to changes in morphology, oxidation level and antioxidant concentration.</p><p>Low density polyethylene (LDPE) with and without an antioxidant additive was selected as insulating material. Test objects with plane electrodes or needle-plane electrodes were prepared by pressure moulding and equipped with aluminium electrodes. Iron particles with a diameter of 45 – 55 μm were introduced to simulate conducting contaminations in the insulation. The test objects were subjected to thermal ageing of 70°C and 90°C and the applied electrical field during ageing ranged from zero to 150 kV/mm. ageing was conducted both with constant DC polarity and with polarity reversals. The ageing period ranged from 4 weeks to 5 months.</p><p>Thermal oxidation was observed in LDPE without antioxidant and this clearly affected the electrical properties. The DC breakdown voltage was reduced by 40% and this was explained by enhanced high-field conduction and increased joule heating due to the oxidation products. It was found that oxidation was prohibited when the thickness of the aluminium electrodes increased. </p><p>Introduction of iron particles reduced the short term DC strength by 20 – 30%, but during long term ageing with constant DC voltage no difference was observed between test objects with and without particles. This was probably caused by screening of the particles by accumulated space charge. </p><p>The experiments showed that abrupt grounding or polarity reversal initiated electrical trees from the needle-electrodes. The longest trees were observed when the test objects had first been subjected to thermal and electrical ageing. The tree formation was caused by the high electrical field arising when the accumulated homocharge around the needle was converted to heterocharge at polarity or grounding,</p><p>The following main conclusions were made from the work:</p><p>*Oxidation is detrimental and must be avoided in HVDC insulation.</p><p>* The antioxidant additive can have a negative influence on the electrical properties under HVDC stress.</p><p>*Polarity reversal or abrupt grounding can initiate electrical trees from protrusions present at the electrode-insulation interface of a HVDC insulation system. </p>

<p>Detta examensarbete har utförts på uppdrag av Stora Enso Skoghall AB.</p><p>För ett vinstdrivande industriföretag som Stora Enso är oplanerade stopp, oberoende av orsak, kostsamma och skall i största möjliga utsträckning undvikas. Att effektivt kunna förutse och förhindra haveri har därför hög prioritet.</p><p>Mätsystemet Argus CC gör, bland annat, analyser av varvtalsavvikelser med hjälp av pulsgivare. Dessa mätningar ligger sedan till grund för inplanering av underhållsstopp.</p><p>Syftet med detta examensarbete är att utvärdera hur utnyttjandet av Argus CC sparar in på kostsamma och onödiga underhållsstopp, samt att konstruera en kommunikationslänk mellan Argus CC och ABB’s styrsystem.</p>

After extensive research during the last decades extruded polymeric insulation is now becoming an alternative to the traditional oil-paper systems for high voltage DC (HVDC) cables. Durability is of great importance for power cables, and the main purpose of this work has been to increase the knowledge of factors controlling the endurance of an extruded polymeric insulation under HVDC conditions. The effect of electrical and thermal ageing on electrical properties like space change accumulation, DC breakdown strength and electrical tree initiation has been investigated and related to changes in morphology, oxidation level and antioxidant concentration. Low density polyethylene (LDPE) with and without an antioxidant additive was selected as insulating material. Test objects with plane electrodes or needle-plane electrodes were prepared by pressure moulding and equipped with aluminium electrodes. Iron particles with a diameter of 45 – 55 μm were introduced to simulate conducting contaminations in the insulation. The test objects were subjected to thermal ageing of 70°C and 90°C and the applied electrical field during ageing ranged from zero to 150 kV/mm. ageing was conducted both with constant DC polarity and with polarity reversals. The ageing period ranged from 4 weeks to 5 months. Thermal oxidation was observed in LDPE without antioxidant and this clearly affected the electrical properties. The DC breakdown voltage was reduced by 40% and this was explained by enhanced high-field conduction and increased joule heating due to the oxidation products. It was found that oxidation was prohibited when the thickness of the aluminium electrodes increased. Introduction of iron particles reduced the short term DC strength by 20 – 30%, but during long term ageing with constant DC voltage no difference was observed between test objects with and without particles. This was probably caused by screening of the particles by accumulated space charge. The experiments showed that abrupt grounding or polarity reversal initiated electrical trees from the needle-electrodes. The longest trees were observed when the test objects had first been subjected to thermal and electrical ageing. The tree formation was caused by the high electrical field arising when the accumulated homocharge around the needle was converted to heterocharge at polarity or grounding, The following main conclusions were made from the work: *Oxidation is detrimental and must be avoided in HVDC insulation. * The antioxidant additive can have a negative influence on the electrical properties under HVDC stress. *Polarity reversal or abrupt grounding can initiate electrical trees from protrusions present at the electrode-insulation interface of a HVDC insulation system.

Detta examensarbete har utförts på uppdrag av Stora Enso Skoghall AB. För ett vinstdrivande industriföretag som Stora Enso är oplanerade stopp, oberoende av orsak, kostsamma och skall i största möjliga utsträckning undvikas. Att effektivt kunna förutse och förhindra haveri har därför hög prioritet. Mätsystemet Argus CC gör, bland annat, analyser av varvtalsavvikelser med hjälp av pulsgivare. Dessa mätningar ligger sedan till grund för inplanering av underhållsstopp. Syftet med detta examensarbete är att utvärdera hur utnyttjandet av Argus CC sparar in på kostsamma och onödiga underhållsstopp, samt att konstruera en kommunikationslänk mellan Argus CC och ABB’s styrsystem.

Examensarbetet utfördes på Koteko AB som är ett ingenjörsföretag inom processautomation, elkraftteknik och industriell elautomation. Rapporten behandlar problematiken som finns idag med att kunna testa och utveckla processmaskiners styrning och reglerförmåga innan leverans samt test av nya koncept. Detta ska göras genom att konstruera en testrigg som ska kunna testa olika körningar med vissa avgränsningar. Rapporten behandlar även dimensioneringen av alla motorer och växellådor som behövs för att testa olika körningar som presenteras senare i arbetet, samt vad som behövs för att styra och köra motorer. / The work was performed at Koteko AB which is a consultant company in process automation, power engineering and industrial electrical automation. The report deals with todays´existing problems of testing and developing process machines’ controller and controllability before delivery and also tests new concepts. This will be done by constructing a test rig that will be able to carry out various test runs with certain limitations. The report also covers the sizing of all engines and gearboxes that are needed in order to test different runs that are presented in the report and also what is needed to control and drive motors.

<p>Vi har genomfört en undersökning av den okända effektförbrukningen på Älvenäs industrihotell Pescator AB. Sedan de ändrade elförsörjningen till industrihotellet och börjat mäta upp olika lokaler har de upptäckt</p><p>att det finns ett stort mörkertal i deras förbrukning. Undersökningen genomfördes dels genom att vi mätte med tångamperemeter och dels genom okulär inspektion där vi gick igenom deras ställverk och centraler. Vi</p><p>fann en mängd områden där det inte fanns mätare men som helt tydligt tillhörde det som måste mätas upp. Bland annat så upptäcktes det att belysningen på ett flertal ställen inte mäts upp.</p> / <p>This assignment is a study of the unknown power consumption at “Älvenäs industrihotell Pescator AB”. They’ve recently changed their power supply and since the change, they have started to record measurements of the power usage. It came to their attention that a large part of the power consumption wasn’t recorded. During our research of the building we first did a visual inspection and then we started to measure the current in different places. We’ve found that a large part of the unrecorded power was lighting.</p>

Vi har genomfört en undersökning av den okända effektförbrukningen på Älvenäs industrihotell Pescator AB. Sedan de ändrade elförsörjningen till industrihotellet och börjat mäta upp olika lokaler har de upptäckt att det finns ett stort mörkertal i deras förbrukning. Undersökningen genomfördes dels genom att vi mätte med tångamperemeter och dels genom okulär inspektion där vi gick igenom deras ställverk och centraler. Vi fann en mängd områden där det inte fanns mätare men som helt tydligt tillhörde det som måste mätas upp. Bland annat så upptäcktes det att belysningen på ett flertal ställen inte mäts upp. / This assignment is a study of the unknown power consumption at “Älvenäs industrihotell Pescator AB”. They’ve recently changed their power supply and since the change, they have started to record measurements of the power usage. It came to their attention that a large part of the power consumption wasn’t recorded. During our research of the building we first did a visual inspection and then we started to measure the current in different places. We’ve found that a large part of the unrecorded power was lighting.

<p>Conventional hydraulic actuators in aircraft are demanding regarding maintenance which implies high operation costs. In recent years the focus therefore has been set on electro-hydrostatic and electro-mechanical actuators.</p><p>The aim of this work is to analyze and evaluate the possibility of introducing electro-mechanical actuators (EMAs) in more electric aircraft applications. The major goal is to optimize the weight of such actuator systems including the electro-machine (electric motor) gear mechanism and power converter, without loss of reliability. Other optimisation criteria on such solutions are low losses and good thermal properties.</p><p>A quasi-static model approach of EMAs is used here in order to decrease the simulation time. It is possible because the low (mechanical) and high (electrical) frequency components are separated in the model, see [1]. The inverters and converters are described as fictive DC-DC transformers with corresponding efficiencies, see [2]. By introducing an object oriented approach the model is flexible and re-usable and can be used as a framework in the future build-up of models of entire MEA aircrafts, see [3].</p><p>Power density, cost and weight of the actuator systems are some of the important key factors for comparing purpose and as a platform for the dimensioning of the aircraft. The next issue becomes the scalability of the model and the key factors, because of the diversity of the actuators used in different parts of the MEA aircraft. Therefore the ambition is set to build up a database of different scalable actuator solutions which among others returns these key factors as output.</p>

Idén med examensarbetet var att konstruera en generell radiolänk med minsta möjliga storlek, som skulle kopplas samman med en redan befintlig konstruktion. Radiokrets CC1100 från Chipcon används tillsammans med mikroprocessor MSP430 från Texas Instruments. För att radiomodulen skall klara ett stort inspänningsområde används en spänningsstabilisator XC6202 från Torex. Det färdiga kortet är ett fyralagerskort med komponenter på en sida, med ett helt jordplan. Komponenterna är placerade så att de fyller sin funktion, samtidigt som de upptar minsta möjliga utrymme egentligen kanske detta med ska vara dåtid? . Med hjälp av en nätverksanalysator undersöktes antennanpassningen så att denna erhöll ett värde på nära 50 W. Radiokretsen programmerades och testades sedan. / The idea behind this project was to construct a general RF-module as small as possible and the RF-module should be able to connect to an existing design. A transceiver from Chipcon, CC1100, was used together with a microprocessor MSP430 from Texas Instruments. To make the RF-module handle a wide input voltage range a voltage regulator, XC6202, from Torex was used. The circuit board is a four layer card with one layer ground and components on one side. The components are placed to full fill there purpose and at the same time make the card as small as possible. With help from a network analyzer the network to the antenna was examined so it obtained a value near 50 W. The RF-module was programmed and tested with good result, but I didn’t participated.

Examensarbete har utförts för AIAB DC Systems i Karlstad. Vår uppgift gick ut på att göra ett övervakningssystem för DC-system. Enheten skall användas för att övervaka isolerade DC-system avseende spänningsnivåer och isolation samt larma vid fel. Tidigare har man haft ett analogt system ute på marknaden men nu vill man ha ett digitalt processorbaserat system. Vi har använt oss av en 8-bitars RISC-processor. Programmeringen har gjorts i assembler med hjälp av ett utvecklings-kit och sköter logiken för övervakningen. Programmet manövreras med två tryckknappar och en display. Programmet vi har tagit fram behöver kompletteras med vissa funktioner. Vi har inte hunnit få klar en prototyp eftersom projekttiden tog slut. / This thesis was performed for AIAB DC Systems in Karlstad. Our task is to make a monitoring system for DC-system. The unit is used to supervise voltage and isolation in isolated DC-systems. The unit shall alarm if there is any failure in the system. The company now has an analog solution on this product but now they want a digital version. An 8-bit RISC processor has been used to take care of the logic. The programming has been done in assembler with the help of a developing kit. The program operates with two buttons and a display. The program that we made needs to be added with some functions. We haven’t got a prototype ready yet due to the project time was expired.