Papers by radojle radetic
Measurement Science Review, 2010
The article describes systematic error analysis for realized chopper low-resistance comparator. T... more The article describes systematic error analysis for realized chopper low-resistance comparator. The objective was to determine optimal working conditions, considering limited resolution (about 10 nV) and resistance variation due to self-heating caused by increase of measuring current. The analysis and performances of realized chopper low-resistance comparator prototype instrument confirmed the initial assumptions of applied principles. The error for 1 A measuring current is 1.15 ppm in the measuring range of 10 mΩ. It is possible to use the same principle for calculation of optimal measuring current and measurement error in other measurement ranges, as well.
Building high precision instruments needs almost ideal operational amplifiers. Effects of offset,... more Building high precision instruments needs almost ideal operational amplifiers. Effects of offset, common mode rejection ratio (CMRR) and other imperfections have to be reduced as much as possible. One way is to apply precision operational amplifiers but their parameters are limited and their price is high. Another approach is to use composite amplifiers proposed in this text. Instead of a single operational amplifier, composite amplifiers are built from two or more operational amplifiers with significant improvements in resulting parameters. The research is started with theoretical analysis. Benefits of the proposed circuits are shown by simulations on the simulation models and measurements on the real model. The theory and practice introduced below could be well included in undergraduate course in analog electronics.
The most exact temperature measurement can be made by using platinum sensors. Temperatures from –... more The most exact temperature measurement can be made by using platinum sensors. Temperatures from –254.3 °C up to +850 °C can be measured with Pt100 sensor. The relationship between resistance and temperature is relatively linear, but for measurements of very high precision, Pt100 working curve should be a little bit improved. The paper describes an efficient way of measurement characteristic linearization by using the analogue electric circuits. The obtained results proved the initial considerations and the Pt100 becomes rather transducer than pure sensor.
Przegląd Elektrotechniczny, 2013
The authors designed and realized an instrument for resistance measuring using the known comparis... more The authors designed and realized an instrument for resistance measuring using the known comparison method. As the first solution it was a single range unit for small resistors. The further investigations had a goal to reach a wide resistance range measuring. It was achieved, but some of appeared difficulties had to be overcome. The paper presents the real instrument characteristics and describes the way of practical solutions of their improvements.
Mining and Metallurgy Engineering Bor
The Mining and Smelting Complex Bor (RTB) is one of the biggest electrical energy consumers in Se... more The Mining and Smelting Complex Bor (RTB) is one of the biggest electrical energy consumers in Serbia, with costs that exceed 3 million USD per month, or between 30 and 40 million USD per year. A complex technological process of copper production comprises mining, concentrate production (flotation), smelting and electrolytic refining. In all these stages a large amount of energy is consumed. The electricity is supplied from the power plants using 5 substations: two of them located in Bor, and the remaining three in Majdanpek. The conditions for delivery and billing of the electrical energy were defined by the contract with the supplier. The methods of billing (calculation) the electrical energy costs were changed several times in the previous 25 years. Although the consumed energy is the largest part of the overall costs, there were also some indirect costs affecting the final monthly price. It is clear that even a minor percentage decrease of costs can lead to substantial savings in the total amount. Hence, different technological and organizational activities were undertaken to reduce these costs. The paper presents primarily the effects of administrative measures on the amount of total electrical energy costs in copper production.
Serbian Journal of Electrical Engineering, 2015
The most exact temperature measurement can be made by using platinum sensors. Temperatures from-2... more The most exact temperature measurement can be made by using platinum sensors. Temperatures from-254.3 °C up to +850 °C can be measured with Pt100 sensor. The relationship between resistance and temperature is relatively linear, but for measurements of very high precision, Pt100 working curve should be a little bit improved. The paper describes an efficient way of measurement characteristic linearization by using the analogue electric circuits. The obtained results proved the initial considerations and the Pt100 becomes rather transducer than pure sensor.
Tehnika, 2015
Operacioni pojačavači (OP) predstavljaju nezaobilazan element u obradi analognih signala. U praks... more Operacioni pojačavači (OP) predstavljaju nezaobilazan element u obradi analognih signala. U praksi je često potrebno da se utvrdi koliko je vremena potrebno da se izlazni napon OP približi stacionarnom stanju sa unapred zadatim maksimalnim odstupanjem. Postojeća literatura ovo pitanje samo dotiče i uglavnom daje neprecizne, nepotpune a ponegde i netačne odgovore. U ovom radu dati su rezultati detaljnog teorijskog istraživanja promene izlaznog napona OP nakon odskočne promene ulaznog napona Ključne reči: operacioni pojačavač, smirivanje OP, maksimalna brzina promene izlaznog napona OP
Przeglad Elektrotechniczny
The authors designed and realized an instrument for resistance measuring using the known comparis... more The authors designed and realized an instrument for resistance measuring using the known comparison method. As the first solution it was a single range unit for small resistors. The further investigations had a goal to reach a wide resistance range measuring. It was achieved, but some of appeared difficulties had to be overcome. The paper presents the real instrument characteristics and describes the way of practical solutions of their improvements. Streszczenie. Autorzy zaprojektowali przyrząd do pomiaru rezystancji bazujący na metodzie porównania. Abu osiągnąć szeroki zakres pomiarowy niezbędne było rozwiązanie wielu nowych problemów. W artykule zaprezentowano możliwości wykonanego przyrządu. (Charakterystyka funkcjonalna komparatora rezystancji oraz możliwości poprawy jego parametrów) Keywords: Resistance comparator, parasitic voltage, output voltage hold circuit, response time, measuring current. Słowa kluczowe: komparator rezystancji, czas odpowiedzi, prąd pomiarowy. Introducti...
Serbian Journal of Electrical Engineering, 2014
The dual-slope ADC (DSADC) is a type of analog-to-digital conversion with low input bandwidths. I... more The dual-slope ADC (DSADC) is a type of analog-to-digital conversion with low input bandwidths. It is pretty slow, but its ability to reject high-frequency noise and fixed low frequencies such as 50 Hz or 60 Hz makes it useful in noisy industrial environments and applications. It provides very good resolution. For the practical measurements in the Institutes laboratory an instrument is designed and realized. The base DSADC method is used, but improved by multiple conversions to make the measuring more precise and the time shorter. The special attention is paid to the problems occurred in practical realization and the way to overcome them. The paper describes the proposed and applied solutions, functional principles and achieved performances of the realized instrument.
Measurement Science Review, 2010
The article describes a new control method of transistor power bridge converter. It is a new one,... more The article describes a new control method of transistor power bridge converter. It is a new one, because of some original solutions and its difference in comparison to existing methods. It's irrelevant of load, similar to the "phase shifted" control method. It is easy to realize using ordinary electronic elements. A significant advantage of method is the possibility of permanent output current monitoring by measuring the voltage sag on a pair of transistors. That allows a very efficient current protection.
Sensors, 2009
The paper describes an improvement of the chopper method for elimination of parasitic voltages in... more The paper describes an improvement of the chopper method for elimination of parasitic voltages in a low resistance comparison and measurement procedure. The basic circuit diagram along with a short description of the working principle are presented and the appropriate low resistance comparator prototype was designed and realized. Preliminary examinations confirm the possibility of measuring extremely low voltages. Very high accuracy in resistance comparison and measurement is achieved (0.08 ppm for 1,000 attempts). Some special critical features in the design are discussed and solutions for overcoming the problems are described.
Journal of Electrical Engineering, 2000
One Way of Output Voltage Hold Circuit Improvement at Low Resistance Comparator The article prese... more One Way of Output Voltage Hold Circuit Improvement at Low Resistance Comparator The article presents a way of improvement the important performances of an electronic low resistance comparator. The practical usage of a realized instrument prototype shows some disadvantages: the time until the result appears at the display is to long (the stationary state establishing sequence should be shorter) because of the negative influence of parasitic voltages. Modification of output voltage hold circuit gives quite convenient instrument response time. The parasitic voltage disturbance is decreased to acceptable value, even though the comparator is modified for multirange measurement. The paper describes some details of a solution and its conformation in practical usage.
Electronics and Electrical Engineering, 2012
Serbian Journal of Electrical Engineering, 2013
The paper presents the real instrument functional characteristics and describes the way of practi... more The paper presents the real instrument functional characteristics and describes the way of practical solutions of its performance improvement. It presents the design process of the instrument made for resistance measuring. In order to achieve desired objectives, a great number of experiments have been carried out during the development. Basically, the comparison method has been applied. At first, it was intended for the small resistor measuring as a single range unit. Later, the device has been improved and upgraded for a wide range resistance measuring. Finally, some of the difficulties have been detected and explained as well. The paper contains solutions developed and applied for their overcoming.
Uploads
Papers by radojle radetic