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Diplomska naloga opisuje izdelavo naprave za merjenje porabe električnih naprav na principu tokovnega merilnega upora. Glede na osnovne specifikacije naprava omogoča merjenje efektivne vrednosti izmeničnega toka do 25 A in kratke tokovne špice do 60 A. Naprava meri tudi električno napetost in fazni kot ter s tem omogoča izračun moči. Za izdelavo naprave je bilo potrebno načrtati električno shemo, izdelati knjižnice za program Altium Designer, izrisati tiskano vezje v tem programu in napisati programsko kodo. Program, napisan v programskem jeziku C, je sposoben z danimi elementi vzorčiti meritve, izračunati želene podatke in jih prikazati uporabniku na prikazovalnik LCD. Ob primerjavi izdelka z referenčnim instrumentom naprava meri znotraj predvidene napake, ki je nižja od 1 %, razen pri najmanjših vrednostih toka, kjer je relativna napaka meritve večja zaradi omejene ločljivosti in napake ničelnih vrednosti. Diploma thesis describes development and construction of the device for measuring power of electric appliances using current measuring resistor - shunt. According to the device specifications it is capable of measuring effective AC current up to 25 A and short current spikes up to 60 A. It also measures voltage and phase shift to be able to calculate the power. For constructing the device electrical schematic had to be designed, libraries for Altium Designer had to be made and PCB was designed. Program code, written in programming language C, is capable of sampling measurements, calculating wanted data and displaying them to the user via LCD. With comparison to the reference instrument the device is measuring within expected error under 1 %, except at lowest values, where the resolution and offset affects the measurement.