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# Machine Riddle No.43 – Excitation transformer vector group

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• #942
Javed alam khan

I am having LAVT panel iwth 6.6KV/415V transformer connection in the panel i want to supply 200N to the AVR panel. I am having Yy11 vector group in LAVT panel and want know whether i should give …
I am having LAVT panel iwth 6.6KV/415V transformer connection in the panel i want to supply 200N to the AVR panel. I am having Yy11 vector group in LAVT panel and want know whether i should give Yd11 or Dy11 excitation transformer connection to AVR panel. Als please provide answer whether vector group of transformer affect the system?

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• #3030
Hamid

A transformer that has one of its windings connected to one of these circuits, as a dedicated transformer, is a converter transformer, or rectifier transformer. IEC standards refer to these transformers as converter transformers, while IEEE standards refer to these transformers as rectifier transformers. Because it is IEEE practice to refer to these transformers as rectifier transformers, that same term is used throughout this discussion. Transformers connected to circuits with a variety of loads, but which may contain some electronic circuits that produce harmonics, are not considered to be rectifier transformers. However, they may have harmonic heating effects similar to rectifier transformers. Those transformers are covered under IEEE Recommended Practice for Establishing Transformer Capability when Supplying Non-Sinusoidal Load Currents, ANSI/IEEE C57.110. One of the major advantages of the ?-Y connection is that it provides harmonic suppression. Recall that the magnetizing current must contain odd harmonics for the induced voltages to be sinusoidal and the third harmonic is the dominant harmonic component. In a three-phase system the third harmonic currents of all three phases are in phase with each other because they are zerosequence currents. In the Y-Y connection, the only path for third harmonic current is through the neutral. In the ?-Y connection, however, the third harmonic currents, being equal in amplitude and in phase with each other, are able to circulate around the path formed by the ?-connected winding. The same thing is true for the other zero-sequence harmonics. If the magnetizing current waveforms of all three phases have approximately the same shape and magnitude, and if the phase angles of the 60 Hz fundamental frequencies are 120

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