Umerjanje števcev električne energije

MUBI, ANŽE (author), Tuma, Tadej (mentor)

V diplomskem delu je opisan postopek razvoja novega merilnika napake, ki je eden ključnih elementov v sistemu za testiranje in umerjanje števcev električne energije. Merilnik napake opravlja meritve impulzov merjenega števca in meritve impulzov etalonskega števca. Podatke o impulzih nato posreduje računalniku, ki izračuna kakšna je napaka. Računalnik podatke o napaki števca posreduje nazaj merilniku napake, ta pa jih prikaže na svojem zaslonu. Moja naloga je bila, da stari merilnik napake posodobim tako, da bo še vedno kompatibilen z ostalimi napravami v sistemu, da bo sprejemal iste ukaze in opravljal iste funkcije, da bo izdelava cenejša kot pri starem merilniku ter da bo na njem možna tudi kasnejša nadgradnja. Problema sem se lotil tako, da sem najprej pregledal stare načrte ter razmislil, kaj bi lahko uporabil. Ugotovil sem, da je procesorski del načrtov neuporaben in ga bo potrebno na novo razviti. Lahko pa sem uporabil načrte za vhodno-izhodne signale ter načrte za serijsko komunikacijo, tako sem tudi dosegel, da je bil merilnik še vedno kompatibilen z ostalimi napravami v sistemu. Zaradi cenejše izgradnje sem se odločil, da bom procesorski in vhodno-izhodni del združil tako, da se bo merilnik napake nahajal na samo enem tiskanem vezju. To sem dosegel tako, da sem uporabil manjše elemente v SMD tehnologiji. Prav tako je bilo treba posodobiti prikazovalnik. Sprva je bilo v načrtu, da bi se uporabil enovrstični LCD zaslon, vendar zaradi slabe preglednosti ta ni bil uporabljen. Potem sem razmišljal, da bi uporabil OLED zaslon, vendar nisem našel nobenega, ki bi dimenzijsko ustrezal ohišju merilnika. Zato sem se odločil, da bom nekoliko predelal stari zaslon, ki uporablja sedem-segmentne zaslone. Ker je bila zahteva, da mora prikazovalnik prikazati pogrešek na tri decimalke natančno, sem preprosto dodal še en karakter, tako da jih je bilo sedem, gonilnik zaslona oziroma kontroler pa prestavil na zadnjo stran zaslona. Merilnik napake je bil izdelan tudi v skladu z zahtevami kasnejše nadgradnje, ki je predvidena na področju komuniciranja z računalnikom. Saj je bil uporabljen mikrokontroler, ki ima že vgrajeno USB komunikacijo in bo sposoben sam izračunati pogrešek ter ga posredovati računalniku.

• Language: Slovenian
• Keywords: merilnik napake, nadgradnja, kompatibilen, 7-segmentni zaslon, mikrokontroler.
• Work type: Bachelor thesis/paper
• Organization: FE - Faculty of Electrical Engineering
• Year: 2015
• PID: 20.500.12556/RUL-73248
• Publication date in RUL: 29.10.2015

Secondary language

• Language: English
• Title: Calibrating Electrical Power Meters

Abstract

The thesis describes the process of developing a new error meter, which is one of the key elements in the system for testing and calibrating electricity meters. The error meter measures the pulses in the measured meter as well as measures the pulses of the standard meter. The error meter forwards the gathered data to the computer, which in turn calculates the error. After that the computer sends the error data back to the error meter, which displays it on its screen. My task was to update the old error meter in such a way as to keep it compatible with other devices in the system and have it respond to the same commands and perform the same functions. However at the same time I had to lower the manufacturing cost as well as make future upgrades on the meter possible. I began tackling the issue by reviewing some old blueprints and considering what I could use. I found the processor part of the blueprints to be useless and needing to be remade, however i was able to use the blueprints for the input-output signals as well as those for serial communication. In this way i made sure my meter is still compatible with other devices in the system. On account of cheaper construction i decided to combine the processor and the input-output parts so as to have the error meter located on a single circuit board. I achieved this by using small elements of the surface-mount technology. It was also necessary to update the display. Initially the plan was to use a single-line LCD screen, yet i decided against using it due to bad visibility. Then i thought of using an OLED screen, but i failed to find one that would fit the housing. Therefore i decided to slightly rework the old seven-segment display. Since the requirement was that the display shows the error to three decimal places, i simply added one more character, making it seven, and i moved the display driver or controller to the back of the screen. The error meter was made in accordance with the requirements of the subsequent upgrade, which is intended to make the meter communicate with a computer. This was achieved by using a microcontroller, which already has a built-in USB-communication and will be able to compute the error and pass it on to a computer.

• Keywords: Error meter, upgrade, compatibility, seven-segment display, microcontroller