Sökning: "current interrupt"

Visar resultat 1 - 5 av 14 avhandlingar innehållade orden current interrupt.

1. 1. Electrochemical characterisation of porous cathodes in the polymer electrolyte fuel cell

   Författare :Frédéric Jaouen; KTH; []
   Nyckelord :polymer electrolyte fuel cell; cathode; mass transport; porous electrode; modelling; agglomerate model; electrochemical impedance spectroscopy; current interrupt; transient techniques; non-noble catalysts;

   Sammanfattning : Polymer electrolyte fuel cells (PEFC) convert chemicalenergy into electrical energy with higher efficiency thaninternal combustion engines. They are particularly suited fortransportation applications or portable devices owing to theirhigh power density and low operating temperature. LÄS MER

3. 2. On the design of hybrid DC-breakers consisting of a mechanical switch and semiconductor devices

   Författare :Jesper Magnusson; Göran Engdahl; Staffan Norrga; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; DC; circuit breaker; hybrid breaker; DC systems; DC; brytare; hybridbrytare; likström;

   Sammanfattning : The interest of using direct current in networks for both transmission and distribution of power is increasing due to the higher efficiency compared to the alternating current used today. As no natural zero crossings exist in direct current, the interruption of fault currents becomes a challenge. LÄS MER

4. 3. Enhanced Active Resonant DC Circuit Breakers for HVDC Grids

   Författare :Tim Augustin; Hans-Peter Nee; Marley Becerra; Jürgen Biela; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Active damping; Actuator; DC circuit breakers; DC grid; DC power systems; Fast mechanical switch; Fault handling strategy; Gas discharge devices; HVDC; HVDC circuit breakers; Multilevel converters; Multiterminal HVDC; Power transmission; Spark gaps; Thomson-coil actuator; Vacuum interrupter; Voltage Source Converter VSC ; Electrical Engineering; Elektro- och systemteknik;

   Sammanfattning : High-voltage DC (HVDC) grids are considered promising for the electricity grid expansion required to integrate renewable energy sources into the existing infrastructure. DC fault currents increase rapidly and lack a current zero crossing. LÄS MER

5. 4. Three Phase Controlled Fault Interruption Using High Voltage SF6 Circuit Breakers

   Författare :Richard Thomas; Chalmers tekniska högskola; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; controlled switching; high voltage; hypothesis testing; circuit breakers; fault interruption; least mean squares regression; power system protection;

   Sammanfattning : A method is presented for implementing controlled fault interruption,using high voltage, SF6 circuit breakers on three phase high voltage powernetworks. The main goal of the method is to synchronize the opening or tripcommands to each phase of a circuit breaker with respect to target currentzero times so that each phase will interrupt with a preselected arcingtime. LÄS MER

7. 5. Urinary leakage and physical activity in young women

   Författare :Kerstin Eliasson; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :Female urinary incontinence; low back pain; pelvic floor muscles; physical activity; risk factors; stop test.;

   Sammanfattning : The effect of recreational physical activity on urinary leakage/ incontinence (UL/UI) with regard to load on the pelvic floor (PF) in young women has not been studied specifically. The aim of the present work was, to survey the prevalence of UL and UI in young and mostly nulliparous women giving special attention to previous and current physical activity and micturition habits and to study the prevalence of UL and UI in women with low back pain (LBP) within the same age-span. LÄS MER