Abstract
Capacitance boxes (CBs) are extensively used in electrical laboratories for calibration of capacitance measurement devices. In this paper, a new recently fabricated CB has been presented to be used for automatic calibrations through its 4096 output capacitance steps in the range from 100 nF to 150 μF. Full specifications and characterization of this new CB have been investigated in detail including its frequency and voltage dependences. The presented CB has relative accuracy in the range from ±5 × 10−5 to ±5 × 10−4 , whereas the relative uncertainty due to the combination effect is less than 15 ppm. The described CB has been used to construct fully automated capacitance measurement system at the National Institute of Standards (NIS), Egypt, using Andeen-Hagerling 2700A, opt. E & opt. C, Ultra-precision Capacitance Bridge up to 1 μF. The second fully automated system for capacitance measurements is formed at NIS by An Agilent E4980A LCR meter, which is used to measure and characterize the higher capacitance values of the fabricated automated CB. Technical comparison between a previous CB and the new introduced one has been done to evaluate its performance.
Highlights
Capacitance has many useful applications in various fields, and most of them require capacitance measurement that can be performed by different methods [1,2]
Three units of the decade capacitance of output values are assembled to establish the recently fabricated Capacitance boxes (CBs) to generate a huge number of the capacitance values, which are mainly used in fully automated calibration of the capacitance meters
The fifteen output capacitance steps could be obtained from each decade separately and the remaining steps are generated by different possible combinations as the examples given in Table 1 [10]
Summary
Capacitance has many useful applications in various fields, and most of them require capacitance measurement that can be performed by different methods [1,2]. A capacitance box (CB) was fabricated using these two fourelement capacitance decades to provide a combination of sequential capacitance steps, automatically, at the common output terminals of the two decades Each one of these decades has four-capacitive elements having nominal. Three units of the decade capacitance of output values are assembled to establish the recently fabricated CB to generate a huge number of the capacitance values, which are mainly used in fully automated calibration of the capacitance meters. The fifteen output capacitance steps could be obtained from each decade separately and the remaining steps are generated by different possible combinations as the examples given in Table 1 [10] This controlling code is stored in the microcontroller ROM, ATMEGA8515-40-. Automatic control is obtained by a special LabVIEW program through a computer USB-to-serial converter
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