Papers by Keyword: Transformers

Abstract: This paper shown and describe this behaviour an original conceptual design of an electrical transformer. The device it is constituted by an electrodynamic actuator and piezoelectric crystals.The input AC voltage generates an axial vibration in the electrodynamic actuator. The axial vibration is transmitted to a piezoelectric crystal which is polarized in the axial direction and generates the output voltage. In a reduced volumes and a single step, it would be possible to reach voltages of tens of MV and great transformation ratios-achieving these voltages is impossible with conventional systems-The transformer works at axial resonance of the piezoelectric crystal. This device operates to the frequency of order kHz; therefore could be used to generate electromagnetic waves. The capacitive and inductive at its output negligible respect conventional transformer. This transformer could be used in countless devices, such as gamma‐ray machines, electron microscope, solid-state propulsion system, Ion thruster, small particle accelerator etc.

Abstract: The Port of Durban (PoD) is currently upgrading its existing power supply to a supply voltage of 132 kV. The existing 33 kV supply cables are old and have exceeded their designed life resulting in unplanned power outages. The existing 33 kV switchgear is old and obsolete as a result it is difficult to maintain. The existing maximum demand capacity will not be able to cater for the additional loads required for the planned expansion developments.The electrical load flow is a very important and fundamental tool for the analysis of any power systems and in the operations as well as planning stages. The electrical load flow study was conducted using PowaMaster software to analyse the behaviour of PoD’s electrical network post implementation of the new substation onto the currently existing network. In performing the electrical load flow study, load diversification is one of the critical input parameters that was considered because it is a true representation of the network behavior. The load forecasting was based on the planned developments commissioned between 2017 and 2027. The electrical load flow study was also to validate if all the new selected reticulation cables and transformers as part of the design have been correctly sized and will be able to operate reliably without compromising security of firm supply with the implementation of all the planned future loads. This report entails the results of the electrical load flow study that was conducted to analyse the voltage stability and system reliability of the PoD’s electrical network in conjunction with new 132/33 kV Langeberg Substation.

Abstract: This paper presents an investigative study on a selected 11 kV distribution feeder network in Akure township, Nigeria, aimed at evaluating power distribution problems and solution proposals for effective application of existing 11 kV feeders for power supply within Nigeria. Based on peak loads recorded on the feeder for 8 years a long term load forecast up to 2021 was carried out using “Trend’ and “Growth’ functions in Excel worksheet. These functions use Method of Least Squares. The peak network load is 8 MW and the expected load in 2021 is 14.5 MW (18.5 MVA at 0.8 power factor) after an exponential growth rate of 0.6 MW per annum. There is need to increase the rating of the power transformer feeding the feeder in order to enhance the security power supply to the network. Furthermore, the Power Company must provide standard input voltage (1.05x11 kV) to the network in order to normalize end-users voltage quality.

Abstract: The aim of this paper is to explore new approaches of monitoring, diagnosis, condition evaluation, and possibility of extending the life of transformers. Research, emphasizing to experimental work, is conducted on a 1.5 KVA single-phase transformer to measure the internal temperature of the primary and secondary winding, using reliable instruments. Special consideration is given to the convenience in the acquisition and management of experimental data, so that the proposed monitoring system can be exploited for all kinds of thermal tests and various loading conditions. The transformer under study is designed and constructed from scratch, according to particular technical specifications. Having completed the transformer construction with the temperature sensors linked in each coil, our aim is to apply various types of loads and record the temperature variation inside the transformer. A process of acquisition and processing of data related to various parameters of transformers is developed so as to predict the behavior and prevent the failure of a transformer.