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Harmonics in transformer magnetizing currents
Proceedings of the American Institute of Electrical Engineers, 1915The purpose of this paper is to show in a concise manner the cause and effects of higher harmonic currents in magnetizing currents of transformers. A hypothetical case is analyzed to show the cause of the harmonics; then the schemes of connecting transformers that are commonly used for polyphase transformation are taken up and the effects of the ...
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Harmonics in opposed current converters
IECON 2012 - 38th Annual Conference on IEEE Industrial Electronics Society, 2012Practical switching devices have finite turn-on and turn-off times. Normally a blanking time is added between the turn-off and turn-on of switches to avoid a short circuit during switching. This blanking time results in a current dependent voltage error of the pulse width modulated output of a converter.
Schellekens, J.M. +3 more
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Harmonic Contributions Evaluation With the Harmonic Current Vector Method
IEEE Transactions on Power Delivery, 2008A method to evaluate harmonic contributions at the point of common coupling is presented in this paper. The proposed approach is based on the harmonic current vector method where reference impedances are introduced. Resistance defined at fundamental frequency with measurements is used as the customer-side reference impedance.
Tomaz Pfajfar +2 more
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Harmonic measurements: current and voltage transducers
199 IEEE Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.99CH36364), 2003An overview of the development of special current and voltage transducers at the National Research Council of Canada for accurate measurements of harmonics in power systems will be presented. The transducers include two-stage and electronically-aided instrument transformers, openable-core AC and AC/DC current transformers, multi-stage clamp-on current ...
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Inductive load current harmonic injection
Proceedings of the Thirty-Fourth Southeastern Symposium on System Theory (Cat. No.02EX540), 2003Induction motor audible noise can be related to the frequency content present in the stator winding currents. These currents produce time varying air gap fluxes which in turn produce exciting forces resulting in vibrations in the mechanical structure. By adding harmonics into the winding currents, additional frequencies can be added to the air gap flux
B. Brzezinski +4 more
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Current Harmonics Measurement by Means of Current Transformers
IEEE Transactions on Power Delivery, 2007This paper analyzes the accuracy of current transformers (CT) when excited with nonsinusoidal currents. It uses a nonlinear model that accounts for the minor hysteresis loop of the core. It was concluded that instrument transformers with accuracy class 0.6 or better provide reasonably accurate measurements of current harmonics magnitudes, however the ...
Alexander E. Emanuel, John A. Orr
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Current harmonics in nonlinear resistance circuits
Electrical Engineering, 1935A semigraphical method of solving for harmonics in the input current to a network containing any number of linear and nonlinear resistances in any combination, when a sinusoidal voltage is applied across the network, is presented herewith. The treatment is restricted to nonlinear resistances in which the d-c volt-ampere characteristic is the same ...
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Harmonic-current-restrained relays for differential protection
Electrical Engineering, 1938DIFFERENTIAL relaying is the commonly accepted means of protecting large power transformers, a-c generators, and station bus systems against internal faults.1 The methods and circuits employed in various instances, while differing in detail, are all fundamentally the same in basic principle.
L. F. Kennedy, C. D. Hayward
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Alternating current sensor with second-harmonic detection
Applied Optics, 2000We describe a novel optical sensor based on the Faraday effect for measuring ac. The sensing element is a piece of material of high Verdet constant placed between polarizers. When the angle between the polarizers differs by 45 degrees, a signal of twice the frequency of the ac is generated--in addition to the usual signal with the same frequency as the
J A, Ferrari +4 more
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Divisors and Harmonic Currents
2001In the first two sections of the present chapter we introduce a conjecture (Conjecture 7.1) which specifies the idea that the characterization of the divisor of the Selberg zeta function of the a-twisted geodesic flow proved in Chapter 3 Section 3.3 is related to its characterizations in terms of a-twisted harmonic currents on SX.
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