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Tehrān, Iran

Faiz J.,University of Tehran | Siahkolah B.,Kavandish Company
Power Systems | Year: 2011

Electrical power generator units supply small and large electrical energy consumers in the most economical way, as such that the delivered electrical energy has acceptable reliability and quality (Billinton and Allan IEE J Electro Power 30(3):231-236, 1984). But for many decades, electricity suppliers had concentrated on generation, transmission and distribution of electrical energy to the consumers. This was while reliability and quality were not taken into account seriously (Bollen Understanding power quality problems. IEEE Press Series on Power Engineering, 2000). The reason was that those days lighting was the most important load of consumers. Of course electrical motors loads have been gradually grown as major loads of the power systems. However, consumers could wait hours for the re-connection of electricity. © Springer-Verlag Berlin Heidelberg 2011.


Faiz J.,University of Tehran | Siahkolah B.,Kavandish Company
Power Systems | Year: 2011

Tap-changer with the ability to change taps while power is on called under-load tap-changer. If a tap-changer is built as such that its fixing requires its being disconnected from the power line, the tap-changer is called no-load tap-changer. © Springer-Verlag Berlin Heidelberg 2011.


Faiz J.,University of Tehran | Siahkolah B.,Kavandish Company
Power Systems | Year: 2011

The most important element in a full-electronic tap-changer is its solid-state switches. Since voltages and currents are AC, the switches used in electronic tap-changer must be bi-directional. Bi-directional switches are tolerable for the positive and negative voltages in the switch-off condition and passing the positive and negative currents in the switch-on conditions (Wheeler et al. Power Eng J:273-282, 2002). In this chapter realization of these switches is presented, static behavior and current commutation is explained. © Springer-Verlag Berlin Heidelberg 2011.


Faiz J.,University of Tehran | Siahkolah B.,Kavandish Company
Power Systems | Year: 2011

Full-electronic tap-changer is faster, has better performance, more capabilities and lower maintenance costs compared with mechanical tap-changers and hybrid tap-changers; however, the cost of electronic tap-changers is higher than that of the conventional ones. © Springer-Verlag Berlin Heidelberg 2011.


Faiz J.,University of Tehran | Siahkolah B.,Kavandish Company
Power Systems | Year: 2011

Tap changing in the mechanical tap-changer generates arc in the contacts of the diverter switches. This arc causes contamination of the oil surrounding the diverter switches and also leads to the erosion of their contacts. Meanwhile, the whole tap changing process in the mechanical tap-changer is basically performed mechanically. Therefore, in the mechanical tap-changers the conditions of oil, contacts and mechanical moveable parts must be examined regularly and are serviced if necessary. However, there is no arc in the full-electronic tap-changer during the tap-changing and also no moveable mechanical part. So, their maintenance cost is very low and almost zero. © Springer-Verlag Berlin Heidelberg 2011.

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