Why Delta-Delta Transformers used in Full Static Exciter System 1

[CuriousElectron]

Hello Gents,
I notice that in Full Static Excitation schemes, a delta-delta connected PPT is utilized. Why delta-delta type? My thoughts are that to provide higher reliability - if one phase fails, you can still supply AC power to your power bridge converter via open delta connected PPT. Also, a closed delta connection eliminates third harmonic voltages.
Thoughts?
Thanks,
EE

 

[edison123]

On top of advantages you mentioned, low voltage, high current invariably uses delta.

The phase magnetizing currents in 3 phase transformer should contain third harmonics to produce a sinusoidal flux. (The third harmonic present in the phase magnetizing current do not appear in the line current since they are co-phase and hence cancel out in the line.)

A sinusoidal transformer output produces less ripple content in the DC output of the static excitation system which in turn produces a good sinusoidal output from the generator.

Muthu

http://www.edison.co.in

 

[waross]

Some codes want the wye point of a wye secondary to be grounded.
A delta winding may be floated, (no ground connection).
In some instances a grounded supply is not allowed for an exciter supply.

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Ohm's law
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It's the LAW!