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DTIC ADA1038248: Shipboard Powerline Transformers: H Emission Chara... |
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by Defense Technical Information Center |
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Harmonics of the powerline fundamental frequency (60/400 |
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Hz) can be generated whenever nonlinear loads are |
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connected to the power distribution system. In some |
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cases, these currents can be the source of radiated |
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magnetic field emissions that adversely affect shipboard |
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equipment. In this memorandum, the magnetic fields from |
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shipboard power transformers were determined using an |
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offline broadband generator as a source of controlled |
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powerline harmonics at frequencies up to 50 kHz. |
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Normalizing the flux density, B, by the harmonic current |
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spectral density in the primary winding, I, was found to |
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be an effective method to compensate for impedance |
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changes and harmonic distortion caused by the transformer |
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magnetic core. It was shown that between 5 and 50 KHz the |
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magnetic fields from transformers rated at 200 W to 5 kVA |
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depend on the distance from the center of the transformer |
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to the field point, the shielding effectiveness of the |
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case, and the current spectrum of the input harmonics. In |
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this frequency band, a transformer surface not containing |
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seams or openings behaves similar to an ideal shielding |
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boundary with respect to frequency (f to the minus 1/2 |
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power dependence). At a distance close to the |
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transformer, the magnetic fields are proportional to 1/R |
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cubed (dipole source); at greater distances they are |
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proportional to 1/R squared. |
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Date Published: 2020-04-02 06:12:42 |
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Identifier: DTIC_ADA1038248 |
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Item Size: 62502379 |
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Language: english |
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Media Type: texts |
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# Topics |
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DTIC Archive; Dalsass, Louis J ; NAVA... |
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@chris85 |
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