No abstract

Design of automobiles has already reached to a level that many uses highly complex and sophisticated computing applications with associated electronics. These high-ended car electronic automation systems require very accurate and steady supply and most of these sensitive car electronics like multimedia systems, navigation units, etc., prone to fail in the presence of transient over voltages through the DC supply lines. Therefore a measurement of transients in automobiles and analysis has been done in order to identify the characteristics and risk levels of such transients for the vehicular control and attendant systems. In evaluating, an extensive survey of the transients carried out at a constant location within the electrical system of many late model automobiles. Transients were measured, rise times ranging from 0.3 μs to 700 μs and pulse durations from few microseconds to hundreds. There are bursts spread over milliseconds while number of transients have rise and fall times (< 5 ns) in the RF range (> 200 MHz). Thus the transient waveforms were first categorized to arrive at a compact set of common types of waveforms and analyzed. The measured transient parameters were compared with the sensitivity of several standard car electronic devices to identify their immunity to the conducted transients. Providing an overview of how to mitigate or reduce the effect of transients in automobiles in order to increase the power system efficiency and reliability, also expected while addressing the sensitivity of devices.

Voltage transients caused by various motors and electrical equipment of tea factories in Sri Lanka have been observed and analyzed. While reporting the major components of transients, this work extends it aspires to investigate the risk of having faults in a three-phase induction motor by monitoring and analyzing the transient voltage waveforms during the starting period. Therefore, common mode transient investigations have been followed. Transient voltage signals have been obtained from high end test setup and altogether 588 waveforms have been analyzed in both the time and frequency domains. In DOL and Star-Delta starting, highest transient amplitude of 688.2 V and 572.1 V have been observed respectively. Highest transient amplitude of 976.4 V and 980.5 V were observed in DOL and Star-Delta switching respectively. Withering and rolling sections dominates over other stages, generating high amplitude transients in average, reflecting same endangerment in energy calculations as presented in voltage integral. DOL starting transients carries fast rise times as 14 ns and in Star-Delta it is 28 ns. In order to assist with the exegesis of these data, transient parameters like rise time, duration, highest peak, etc.… have also been presented in statistical basis.

Electrical equipment and supply cables demand a better quality of supply, with the recent advancements in integrated sensitive solid-state controls. Divergently, proliferated heavy inductive motors and some performance additions based on power electronics have introduced power quality issues to the network. Thus, this study mainly investigates the impact of switching transients generated by electromechanical machines in industrial power systems on insulation deterioration while taking transient overvoltages due to capacitor bank switching also to support. Transients with a high rate of rise are likely to catalyze the degradation of the insulation quality and break down the insulating material through ionization. These steeply passing overvoltage stresses let partial discharges ensue, which can attack the insulation over long service. To unveil this danger, 314 common-mode transient waveforms were measured in the electrical machines of five tea factories in Sri Lanka, in a 50 ms measurement window, taken in 55 measuring attempts. Most of the transients observed are in the form of a damped oscillatory waveform tailed by fast exponential collapse. That correlates to insulation degradation having a very steep rise as 30.04 V/ns, the highest at the withering section. When machines are heavily loaded, situations tend to generate transients with high amplitudes. There were transient bursts that spread as 426.3 ms, while 14 ns fast rise times were recorded from withering motors. Unlike electrical resonance and power-frequency overvoltages, electromagnetic switching transients last even less than 100 ms. To underline this, an analysis of the frequency domain of transients was also presented, which proves high density of high-frequency components reaching 107 kHz range. Accepting the fact that frequency and amplitude are always under the influences of innumerable dynamics, the observational evidence of the study endorses that electrical stress built by the transient nature of the factories reduces the life expectancy of electrical insulation.