Sökning: "konstruktion"

Visar resultat 21 - 25 av 349 avhandlingar innehållade ordet konstruktion.

1. 21. Modeling and Verification of Ultra-Fast Electro-Mechanical Actuators for HVDC Breakers

   Författare :Ara Bissal; Göran Engdahl; Elena Lomonova; KTH; []
   Nyckelord :Actuators; Armature; Capacitors; Circuit breakers; Coils; Damping; Eddy currents; Elasticity; Electro-mechanical devices; Electromagnetic forces; Finite element methods; HVDC transmission; Image motion analysis; Magnetic domains; Magnetic flux; Magnetic forces; Magnetic materials; Magnets; Thermal analysis; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : The continuously increasing demand for clean renewable energy has rekindled interest in multi-terminal high voltage direct current (HVDC) grids. Although such grids have several advantages and a great potential, their materialization has been thwarted due to the absence of HVDC breakers. LÄS MER

3. 22. On the Design of Ultra-fast Electro-Mechanical Actuators

   Författare :Ara Bissal; Göran Engdahl; Torbjörn Lembke; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Electro-mechanical drive; Circuit breakers; HVDC transmission; Eddy currents; Finite element; Electromagnetic; Thermal; Mechanical; Coils; Armature; Image motion analysis.;

   Sammanfattning : The continuously increasing demand for connecting electric grids with remote renewable energy sources such as wind power and photovoltaic cells has rekindled interest in high voltage direct current (HVDC) multi-terminal networks. Although HVDC networks have numerous benefits, their adoption relies entirely on the availability of HVDC circuit breakers which, compared to traditional alternating current circuit breakers, have to operate in a time frame of milliseconds. LÄS MER

4. 23. Propagation of some coherent and partially coherent laser beams

   Författare :Yangjian Cai; Sailing He; Franco Gori; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; : dark hollow beam; elliptical Gaussian beam; flat-topped beam; twisted anisotropic Gaussian Schell-model; partial coherent; propagation; paraxial optical system; Electrical engineering; electronics and photonics; Elektroteknik; elektronik och fotonik;

   Sammanfattning : In this thesis, we investigate the propagation of some coherent and partially coherent laser beams, including a dark hollow beam (DHB), an elliptical Gaussian beam (EGB), a flat-topped beam and a twisted anisotropic Gaussian Schell-model (TAGSM) beam, through a paraxial optical system or a turbulent atmosphere. Several theoretical models are proposed to describe a DHB of circular or non-circular symmetry. LÄS MER

5. 24. Magnetizing Currents in Power Transformers : Measurements, Simulations, and Diagnostic Methods

   Författare :Claes Carrander; Hans Edin; Göran Engdahl; Rajeev Thottappillil; Amr Adly; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Transformer core; diagnostics; three-phase; no-load; hysteresis; modeling; resonance; remanence; delta; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : This thesis demonstrates a method for transformer core diagnostics. The method uses the no-load current of the transformer as an indicator, and gives different characteristic signatures for different types of faults or defects. Using the no-load current for the diagnostic gives high sensitivity. LÄS MER

7. 25. On methods of measuring magnetic properties of power transformers

   Författare :Claes Carrander; Göran Engdahl; Anders Bergqvist; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; No-load; magnetizing current; losses; diagnostics; delta; three-phase; power transformer; magnetic core; electrical steel; measurements; simulation; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : The core of a power transformer can weigh hundreds of tons, and represents a significant part of the total ownership cost of the transformer, in terms of both the construction cost and of the monetary cost of losses. It is therefore desirable to have a method of diagnosing the core to ensure optimal performance, and to enable the operator to plan repairs of damaged or defective cores. LÄS MER