Termo-električna analiza in optimizacija elektromagnetnega sprožnika selektivnega tokovnega odklopnika

TOPČAGIĆ, ZUMRET (author), Križaj, Dejan (mentor)

Delo opisuje izgradnjo modela primernega za statično in dinamično elektro-termično numerično analizo delovanja integriranega elektromagnetnega sprožnika. V numeričnem modelu je bil upoštevan vpliv temperature na spremembo električnih lastnosti navitja, kar je rezultiralo v sklopljenem reševanju elektro-termičnih enačb. Poleg tega model omogoča študijo vpliva magnetnega polja na magnetne sile v sprožniku. Največji problem predstavlja ustrezna določitev termičnih mejnih pogojev, kar se do določene mere reši s primerjavo modela in eksperimentalno izmerjenih vrednosti pri statičnih razmerah. S pomočjo zgrajenega modela je bila izvedena statična in dinamična analiza delovanja sprožnika pri različnih tokovnih vzbujanjih (I 1 do I 4 ). Glede na v zažetku predpostavljene poenostavitve model ustrezno prikazuje potek prehajanja toplote iz navitja na bimetalni element, kar je bistven podatek za ustrezno načrtovanje in optimizacijo delovanja sprožnika. Model omogoča analizo vpliva spremembe geometrijskih parametrov in tudi spremembe materialov na delovanje sprožnika. V drugem delu sem se osredotočil na optimiacijo integriranega sprožnika. Optimizacija integriranega sprožnika je potekala v smeri spreminjanja geometrije sprožnika. Na osnovi analize rezultatov iz prvega dela sem določil osnovne spremembe, ki jih bom obravnaval. Poudarek je bil na iskanju takšnih sprememb geometrije ali materialov sprožnika, da bo prenos toplote od navitja do bimetalnega elementa čim hitrejši. Ta problem se je v praksi najizraziteje pokazal pri toku I 4 , zato sem se v analizi osredotočil ravno na elektro-termične razmere pri tem toku. Z upoštevanimi geometrijskimi spremembami kotve je bil dosežen hitrejši toplotni pretok od navitja v smeri bimetalnega elementa. Posledično je bilo doseženo hitrejše segrevanje bimetalnega elementa. Kotva, skrajšana za 4 mm, je pri vzbujalnem toku I 4 v času 40 sekund povzročila za 6 stopinj Celzija višjo temperaturo bimetalnega elementa kot v primeru neoptimiranega sprožnika.

• Language: Slovenian
• Keywords: Sklopljena termo-električna analiza, tokovni odklopnik, numerično modeliranje
• Work type: Master's thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2015
• PID: 20.500.12556/RUL-73444
• Publication date in RUL: 16.11.2015

Secondary language

• Language: English
• Title: Thermo-electric analysis and optimization of an electromagnetic tripping unit of a selective circuit breaker

Abstract

This work describes development of a numerical model suitable for stationary and time dependent electro-thermal numerical analysis of an integrated electromagnetic trigger. In the model a temperature influence on electrical properties of the windings was incorporated resulting in a coupled thermo-electromagnetic analysis. This model also enables analysis of the magnetic field and forces inside the integrated trigger. The biggest problem was setting the correct boundary conditions for thermal analysis. This was partially solved by comparing calculated and measured thermal states in stationary conditions. With given numerical model the stationary and time dependent analysis for different excitation currents (from I 1 to I 4 ) were performed. Taking into account given simplifications the model enables analysis of heat transfer from the winding to the bimetal element which is crucial element for planning and optimization of operation of the integrated trigger. The numerical model enables analysis of geometrical and materials parameter changes on the operation of the trigger. In the second part of this work the focus was on optimization of the integrated trigger. Optimization was performed in by studying the influence of geometrical modifications on trigger operation. The goal was to find such a geometry or material changes which would result in fastest heat flow from the winding toward the bimetal element. The heat transfer toward the bimetal element was most critical when the trigger was loaded with the current I 4 , because of that we have analysed thermo-electromagnetic states of the integrated trigger excited with I 4 . Heat flow from the winding toward the bimetal element was improved by modifications of the anchor geometry. Consequently, faster heating of the bimetal element was achieved. The anchor was shortened for 4 mm which at the winding current I 4 caused 6 degC higher temperature of the bimetal element compared to the non optimized trigger.

• Keywords: Coupled thermo-electromagnetic analysis, current breaker, numerical simulations