Milutin Pavlica

The impact of the induction motor on short-circuit current

Simplified analytical models for calculation of the induction motors short-circuit current are presented. Laboratory tests have been performed on two induction motors with low power rating, 26 kW and 122 kW, respectively, in order to measure their short-circuit current. Results calculated according to the available literature have been compared to those acquired by testing. Calculations have also been made for a high-voltage induction motor rated 1250 kW, whose parameters have been known.

Some problems of synchronous hydro-generator temperature measurement

During complex measurements on synchronous hydro-generator 35 MVA, among other measurements, temperature measurement of stator winding end was realized. The real aim of this temperature measurement was to determine influence of excitation winding on armature windings during different operation points. This paper describes the measurement procedure, measurement system and some problems that occurred during this measurement.

Measurement of hydro-generator's end region temperature

Paper presents results of measurements of hydrogenerators end region steady state temperatures. Measurements were carried out in case of two hydro-generators, 65 MVA and 40 MVA respectively, installed in the same power plant. Four thermal probes were placed in each of the generators. Some of the tests, carried out for under-excited load conditions, had to be interrupted because the temperature of the end region exceeded 130degC. Results indicate that end region temperature should be monitored.

Induction motor's contribution to short circuit current

Simplified analytical models for calculation of the induction motors momentary short circuit current are presented. Laboratory tests have been performed on two induction motors, in order to measure their contribution to short-circuit current. Results calculated according to the available literature have been compared to those acquired by testing.

Large turbogenerator's synchronous reactance's load dependence determined by measurements

The paper presents research on underexcited turbogenerator operation capability. Measurements of basic electrical values for various loads have been carried out in case of 247 MVA turbogenerator. Synchronous reactance for various loads has been determined from measurements. Its influence on underexcited operation limits has been evaluated.

Analysis of hydro-generator's losses determined by calorimetric method

The paper presents the results of determination of losses for 12 hydro-generators performed on-site using calorimetric method. The losses were determined in two different ways: from prescribed off-line tests and from online tests. The analysis of the acquired results in some cases shows significant differences.

Ensuring synchronous generator special standstill tests

During extensive testing of 35 MVA synchronous generator, some tests in standstill were conducted. For those tests rotor was blocked and different DC currents were driven through excitation and armature winding. In order to ensure all necessary conditions for such tests lots of preparations were made. This paper will thoroughly explain all problems that come out of such request and solutions for them.

Influence of synchronous generator's stator core on partial discharge on-line measurement

Paper presents the results of on-line partial discharge (PD) measurements of large hydro-generators stator winding. Measurements were performed for different load conditions using temporary installed capacitive couplers and applying high frequency phase resolved method. The results show high PD levels caused by core arcing and its change with rise of core temperature.

Computer role in electrical machines courses - synchronous generator's power chart Web application

This paper presents a specific use of a computer in electrical machines courses. Computer simulations over Internet have proven themselves useful because of their flexibility and availability. Such simulation of synchronous generators power chart has been custom made to help the electrical engineering students acquire better understanding of the subject.