This paper covers the analysis of electrical parameters which affect the accuracy of current-to-voltage transducer based on Rogowski coil. The actual transducer is designed for high-accuracy measurement of AC current (up to 20 A at power supply frequency of 50 Hz, with the aiming uncertainty of 100 parts per million). The primary source of uncertainty of ac current measured by this type of transducer is non-ideal geometry (i.e. mutual position between primary conductor and secondary coils). Except these influencing parameters, the temperature dependence of coil geometry affect the accuracy as additional source of uncertainty, as well as the self resonance frequency, especially on higher frequencies. The analysis of influence of these parameters and temperature compensation of transformer transimpedance makes the topic of this work.

One of the most applied procedures for detention of incipient faults in power transformers, such as partial discharges, electrical arcing and overheating, is the analysis of the concentration of gases dissolved in the isolating mineral oil. This analysis usually is carried through in a laboratory through chromatography in gaseous phase. Although it presents trustworthy results the chromatography brings some inconveniences as the need of a periodic sampling along with the distance from the laboratory to the substation of electric energy. There are some measurement systems available with the capacity to carry through this analysis in the field. However these devices are costly, not justifying its use in a dedicated form in low cost power transformers. In such a way, a project for the monitoring of multiples transformers was initiated using only one measurement system. One of the most important features of the developed equipment is its capability to remote control and monitor. Thus, an Internet procedure based in GPRS (General Packet Radio Service) technology was developed. The use of the GPRS for remote communication made possible the development of an equipment more independent, capable to transmit and receive commands from different substation of electric energy.

A mobile station has been designed to monitor the air quality. Several of those stations are to be installed on the rooftop of taxis and buses in order to build a real time map of the air quality of a city. The modules are equipped with gas concentration measurement modules for 5 different gases (CO, NO₂, O₃, SO₂, and CO₂), GPS receivers for localization, GSM/GPRS modules for communication and solar panels/batteries for completely autonomous operation. Here we describe in detail the choices made and the problems encountered in the design of the solar powering system for this mobile station.

This work illustrates an analysis of Rogowski coils for power applications, when operating under non ideal measurement conditions. The developed numerical model, validated by comparison with other methods and experiments, enables to investigate the effects of the geometrical and constructive parameters on the measurement behavior of the coil.

For monitoring natural landslide disaster, wireless sensing node network is so effective system. The sensing node is constructed by some sensors (acceleration, soil moisture, GPS and so on), data processing unit (micro processor) and wireless communication unit. The network topology we have constructed is mesh type. In the system, at sensing landslide, the node will transport the information to host system through the node network by using wireless communication. Generally, in natural field, the landslide is sensed as the changing of acceleration. But, it is so difficult to distinguish the landslide obviously. The acceleration of the sensing node will change by not only the landslide disaster but also collision with several hard blocks like stones. This paper describes the distinction method of landslide disaster by using only the signal of acceleration sensor mounted in the sensing node. The method focuses the time transition of frequency distribution of the acceleration signal. Observing the time transition, the situations of sensing node have been distinguished.