A data logger has been built to record, for a month, the power consumption of various equipment and the temperature at different points inside and outside of a radio communication base station operated by Vodafone Portugal. Here we show how the concerns with measurement uncertainty led us to choose an analog system over a digital one for AC power measurement.
An analytical expression for the standard deviation of Total Harmonic Distortion (THD) estimation is derived. It applies to the case where the estimator uses sine fitting. It is shown that, in common circumstances, it is inversely proportional to the actual value of THD, the signal-to-noise ratio and the square root of the number of samples. The proposed expression is validated both with numerical simulations and an experimental setup using a Monte Carlo procedure.
The development of accurate computer control of a 3 MV Van de Graaff accelerator operation is described. The developed system comprises the accelerator turn-on and turn-off procedures during a normal run, which includes the setting of the terminal voltage, ion source light up, beam focusing and control of ion beam current and energy during operation. In addition, the computer monitors the vacuum and is able to make a detail register of the most important events during a normal run. The computer control system uses a LabVIEW application for interaction with the operator and an I/O board that interfaces the computer and the accelerator system. For everyday operating conditions the control implemented is able to turn-on and off the machine in about the same time as a specialized technician. In addition, today more users can make experiments in the accelerator without the help of a specialized operator, which in turns increases the number of hours during which the accelerator can be used.