Comparative Analysis of European and American Standards for Maximum Fault Current Calculations on Medium Voltage Mine Power Networks

Continuous work of mine supplying electrical power networks is a prerequisite to ensure the continuity of the mining process and the safety of its crew. The choice of the appropriate method for calculating short-circuit currents is therefore particularly important in terms of both economic and safety considerations. The methods used are always a compromise between the accuracy of obtained results, computational complexity and availability of data necessary for calculations. The study compares the two most common standards for calculating maximum short-circuit currents - IEC and ANSI/IEEE. The study presents the most important interrelationships that describe the characteristic magnitudes of short-circuit currents for IEC standard and for the ANSI/IEEE standard. This comparison has been done on the basis of novel calculations performed on a typical MV mine network. The results of the calculations showed a high contiguity of the results despite the different methodological assumptions for rotating machines modelling and for determining the equivalent value of resistance and reactance of the network where the fault occurred, and the extent of assumed simplifications

Monitoring of the pulsation cycle in a jig using a radiometric density meter

Application of a radiometric density meter to monitor changes in coal bed density during a pulsation cycle in a jig has been presented. The signal from the radiation detector has been filtered in an adaptive filter to react properly to rapid changes in density. The radiometric density meter has been used to measure density of a coal layer 3 cm thick and 30 cm wide. The distribution of the material density along the bed height has been measured during field tests performed on the industrial jig. Changes in density have shown the process of material loosening and its compression during each cycle of pulsations

Monitoring of the pulsation cycle in a jig using a radiometric density meter

Application of a radiometric density meter to monitor changes in coal bed density during a pulsation cycle in a jig has been presented. The signal from the radiation detector has been filtered in an adaptive filter to react properly to rapid changes in density. The radiometric density meter has been used to measure density of a coal layer 3 cm thick and 30 cm wide. The distribution of the material density along the bed height has been measured during field tests performed on the industrial jig. Changes in density have shown the process of material loosening and its compression during each cycle of pulsations