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Accurate AC Current Measurements
Nováková Zachovalová, Věra ; Vrabček,, Peter (referee) ; Draxler,, Karel (referee) ; Beneš, Petr (advisor)
In recent years precision measurement of alternating currents goes through large progress especially because of improvements in metrology of electric power, which is related to reduction of electricity consumption. Therefore, more precise measurement of electric energy, power and power quality is required. Measurement range is extending and number of measured frequency points is growing up to 100 kHz. Development of current to voltage transducer with normalized output voltage (0,5 V - 1 V) is in progress because of their easy integration in different measuring systems.. From big area of alternating current metrology this dissertation focuses on development of improved cage shunts for measurement of alternating currents in range 10 mA - 100 A, 10 Hz - 100 kHz. Main objective of this dissertation is to develop theoretical model of existing cage shunts, which will assist design of new improved cage shunts construction. In this dissertation the analytical model of CMI’s cage shunts was established, based on calculating of trans-impedance from cascade matrix of passive two-port which is representing the shunt. Trans-impedance can be used for AC-DC difference and phase error calculation, which are two basic parameters of shunts. Uncertainty analysis of the model was done by means of Monte Carlo method. Next, this dissertation also concentrates on suitable measurement methods of phase error, AC-DC difference, and power a temperature coefficient of resistance. These measurements method were used for calibration of existing CMI’s cage shunts and so the model’s verification was made. Finally, theoretical optimization of existing CMI’s cage shunts constructions and theoretical designs of 20A, 50A and 100A shunts were done using sensitivity analysis results.
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Low level DC voltage measurement
Obšilová, Lucie ; Nováková Zachovalová, Věra (referee) ; Havlíková, Marie (advisor)
This thesis deals with low level DC voltage measurement by three methods. First part of this thesis describes each method. It is about potentiometric method, reference step method and direct method. This thesis also describes Josephson voltage standard which was used for calibration nanovoltmeter and Zener reference. The theoretical part of this thesis also deals with the evaluation of key comparison data. The main goal of this thesis is the comparison of methods used to measure low level DC voltage. The practical part of the thesis deals with the implementation of measurement with all methods in cooperation with Czech metrology institute. The measured values are processed including uncertainty evaluations. The final part of this thesis focuses on comparison of measurement methods. The key comparison reference value and the degree of equivalence of the measurement of each method are determined. Next part of comparison consisted of graphic comparison of methods. The end of the thesis contains evaluation of the achieved results.
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Meaurement process automatization of deviations and stability of oscilators
Čermák, Jan ; Nováková Zachovalová, Věra (referee) ; Havlíková, Marie (advisor)
This Master´s thesis on a topic ,,Meaurement process automatization of deviations and stability of oscilators‘‘ describes methods for measuring the difference of time scales. Using this method, calculates the parameters of the oscillator, which is also describes in this work. Parameters of the oscillator means inning and stability. Describes is the procedure for calculating the uncertainties and their presentation in the final calibration sheet. This Master´s thesis also describes the practical measurement with this method in the Czech metrology institute in Brno. Measurement of the parameters of oscillator by the method of measurement of the difference of time scales is carried out automatically by computer. This Master´s thesis deals with the creation and development of new software and thus the automation of the entire task.
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Meaurement process automatization of Zener reference
Bábek, Tomáš ; Nováková Zachovalová, Věra (referee) ; Havlíková, Marie (advisor)
This thesis deals with metrology specialized to DC voltage. In the begining of thesis is explanation of technical terms from metrology, summarization of units from International System and explanation of the standards and its kinds in the context of metrology. Primary standards of DC voltage based on Zener diodes and Josephson effect are described as well. In cooperation with Czech metrology institute in Brno this work is focused on automatization of measuring Zener reference standards (ZRS). Goal of this project is to automatize the measuring of Zener reference standards and its relationship with Josephson voltage system using scanner. To do this, there is a need to find out offsets, that can develop on scanner's channels. There is a theoretical analysis of measuring made on the scanner and their uncertainties. Aim of the solution is computation of scanner channels offsets using everyday automatic measuring the system of Zener reference standards (ZRS). For measuring the LabView was used and for computing the data from measured values the Matlab was used. This thesis should short the time needed when measuring DC voltage references, measure values of DC voltage standards and set the scanner channels offsets. In the end there is a summarization of offsets measured on individual scanner channels.
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Accurate AC Current Measurements
Nováková Zachovalová, Věra ; Vrabček,, Peter (referee) ; Draxler,, Karel (referee) ; Beneš, Petr (advisor)
In recent years precision measurement of alternating currents goes through large progress especially because of improvements in metrology of electric power, which is related to reduction of electricity consumption. Therefore, more precise measurement of electric energy, power and power quality is required. Measurement range is extending and number of measured frequency points is growing up to 100 kHz. Development of current to voltage transducer with normalized output voltage (0,5 V - 1 V) is in progress because of their easy integration in different measuring systems.. From big area of alternating current metrology this dissertation focuses on development of improved cage shunts for measurement of alternating currents in range 10 mA - 100 A, 10 Hz - 100 kHz. Main objective of this dissertation is to develop theoretical model of existing cage shunts, which will assist design of new improved cage shunts construction. In this dissertation the analytical model of CMI’s cage shunts was established, based on calculating of trans-impedance from cascade matrix of passive two-port which is representing the shunt. Trans-impedance can be used for AC-DC difference and phase error calculation, which are two basic parameters of shunts. Uncertainty analysis of the model was done by means of Monte Carlo method. Next, this dissertation also concentrates on suitable measurement methods of phase error, AC-DC difference, and power a temperature coefficient of resistance. These measurements method were used for calibration of existing CMI’s cage shunts and so the model’s verification was made. Finally, theoretical optimization of existing CMI’s cage shunts constructions and theoretical designs of 20A, 50A and 100A shunts were done using sensitivity analysis results.
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Low level DC voltage measurement
Obšilová, Lucie ; Nováková Zachovalová, Věra (referee) ; Havlíková, Marie (advisor)
This thesis deals with low level DC voltage measurement by three methods. First part of this thesis describes each method. It is about potentiometric method, reference step method and direct method. This thesis also describes Josephson voltage standard which was used for calibration nanovoltmeter and Zener reference. The theoretical part of this thesis also deals with the evaluation of key comparison data. The main goal of this thesis is the comparison of methods used to measure low level DC voltage. The practical part of the thesis deals with the implementation of measurement with all methods in cooperation with Czech metrology institute. The measured values are processed including uncertainty evaluations. The final part of this thesis focuses on comparison of measurement methods. The key comparison reference value and the degree of equivalence of the measurement of each method are determined. Next part of comparison consisted of graphic comparison of methods. The end of the thesis contains evaluation of the achieved results.
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Meaurement process automatization of Zener reference
Bábek, Tomáš ; Nováková Zachovalová, Věra (referee) ; Havlíková, Marie (advisor)
This thesis deals with metrology specialized to DC voltage. In the begining of thesis is explanation of technical terms from metrology, summarization of units from International System and explanation of the standards and its kinds in the context of metrology. Primary standards of DC voltage based on Zener diodes and Josephson effect are described as well. In cooperation with Czech metrology institute in Brno this work is focused on automatization of measuring Zener reference standards (ZRS). Goal of this project is to automatize the measuring of Zener reference standards and its relationship with Josephson voltage system using scanner. To do this, there is a need to find out offsets, that can develop on scanner's channels. There is a theoretical analysis of measuring made on the scanner and their uncertainties. Aim of the solution is computation of scanner channels offsets using everyday automatic measuring the system of Zener reference standards (ZRS). For measuring the LabView was used and for computing the data from measured values the Matlab was used. This thesis should short the time needed when measuring DC voltage references, measure values of DC voltage standards and set the scanner channels offsets. In the end there is a summarization of offsets measured on individual scanner channels.
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Meaurement process automatization of deviations and stability of oscilators
Čermák, Jan ; Nováková Zachovalová, Věra (referee) ; Havlíková, Marie (advisor)
This Master´s thesis on a topic ,,Meaurement process automatization of deviations and stability of oscilators‘‘ describes methods for measuring the difference of time scales. Using this method, calculates the parameters of the oscillator, which is also describes in this work. Parameters of the oscillator means inning and stability. Describes is the procedure for calculating the uncertainties and their presentation in the final calibration sheet. This Master´s thesis also describes the practical measurement with this method in the Czech metrology institute in Brno. Measurement of the parameters of oscillator by the method of measurement of the difference of time scales is carried out automatically by computer. This Master´s thesis deals with the creation and development of new software and thus the automation of the entire task.
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