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CONCLUSIONSHarmonic current components increase power system loss, cause an excessive heating in rotating machinery, can create significant interference with communication circuits and cause an excessive heating in power systems components such as cables, busbars, capacitors and transformers. Due to the importance of busbar in distribution systems harmonic effects on busbar joints are studied in this thesis.The main points that are extracted from this thesis are summarized as follows:• Harmonics is an issue that is not going to go away any time in the future, this is due to the wide use of solid state devices for control and energy conservation purposes and due to wide spread of computer in domestics, commercials and industries applications.• A new techniques of straight bus bar joints including its mechanical design, performance, the mathematical equations for calculating tension forces, compression forces and shearing forces affecting on the busbar joint and the maximum short circuit current which can be carrying without joint failure.• Harmonic effects on busbar joint life time state that as the harmonic increase the life time of busbar joints decrease due to the increase in temperature rise which affects the contact resistance of joints, increasing length of joints to a certain limits improve the performance of busbar joints, also variation of ambient temperature due to change in seasons affects the lifetime of joints, increasing the current of busbar joints is the main source of power losses and temperature rise of joints which short its life time and finally the clamping force affecting on the two member of joints improve joint life time as clamping force increase to a certain limits .• Harmonics increase the transient and steady state temperature distribution along busbar joint. The change in temperature distribution is proportion to the amount of harmonics and loads causing harmonics attached with these busbars. Also, the distribution of temperature rises at the ends of joints is more than the temperature at the middle of the joint.• Effect of harmonics on power capacitors shows that the capacitance of power capacitors increase by about 7% of its value as its temperature coefficient of capacitance increase as temperature increase (TCC is +ve) and decrease by the same value as temperature coefficient of capacitance is negative (TCC is –ve).• The overall change in capacitance due to change in season, tolerance, ambient temperature and harmonic effects ranging between (-7% ? ?c ? 12%) which increase its effects on passive filter and resonance point.• The change in capacitance of passive filter affects the impedance of filter, the current passing across the filter arms and the voltages of the filter capacitors.• The resonance points between filter impedance and source impedance (transformers) will be changes due change in filter impedance’s and may cause resonance at another order of harmonic existed on power system.• The important methods of eliminating the effects of changing capacitance of filter are using capacitors of positive and negative temperature coefficients connected in series or parallel in the systems.For future, we have ask a deterioration charts and damage charts as voltage DROP and temperature rise for busbars and cables and these have to be put in the catalogues. For future work we have to study the effects of harmonics on power cablesbecause of its high costs and important in distribution systems. Fore future, we need to study in detail harmonics effects on tension, compression and shear forces affecting on busbar joints and cables. Fore future work we have to design wireless system for contact problems, as sender and receiver to collect the data. . Also, we need small electronic cards to be connected on switchboards to give alarm if contact deteriorates, and to disconnect the supply if necessaryREFERENCES[1] T. Longhand, T.W. Hunt and A. B recknell, “Power Capacitor Handbook,” Butterworth, 1984.[2] Aly A. Mahmoud, “Power system Harmonics’ An assessment,” IEEE tutorial course, power system harmonics, 1984, pp. 1-8.[3] Common wealth Sprague home page, “Harmonic Filtering,” Technical data, world wide web at : http : // www. Comsprage.com.[4] J.J.Toth III and D. J. Velazquez, “Benefits of an Automated on-line Harmonic Measurement Sytem,” IEEE Trans. on Ind. Appl., Vol. IA-22, No. 5, Sept./Oct. 1986, pp. 952-963.[5] A. McEachern, W.M. Grady, W.A. Moncriff, G.T. Heydt and M. McGranaghan” Revenue and Harmonics; an Evaluation of some proposed rate structure,” IEEE Trans. on power Delivery, Vol. 10, No. 1, Jan. 1995, pp. 474-482.[6] Elham B, Makram, Regan B. Haines and Adly A. Girgis, “Effect of Harmonic Distortion in Reactive power Measurement,” IEEE Trans. on Ind. Appl., Vol. 28, No. 4, July/ Aug. 1992, pp. 782-787.[7] IEEE working group on sinusoidal situations effects on meter performance and definitions of power, “Practical Definitions for Powers in systems with Nonsinusoidal Waveforms and Unbalanced Loads; a Discussion,” IEEE Trans. on Power Delivery, Vol. 11, No. 1, Jan. 1996, pp. 79-85.[8] P.S. Fillipski and P.W. Labaj, “Evaluation of Reatctive Power Meters in the Presence of High Harmonic Distortion,” IEEE Trans. on Power Delivery, Vol. 7, no. 4, Oct. 1992, pp. 1793-1799.[9] W.M. Grady, G.T. Heydt, A.A. Mahmoud and R.D. Shultz, “System
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