On 5 Feb, 09:29, firstname.lastname@example.org wrote:
The following conditions must exist for transformers to operate
satisfactorily in parallel:
1. Connection diagrams must be identical. Paralleling transformers
with different connection diagrams is similar to short circuiting
their secondary windings.
2. Voltage ratios must be the same. If voltage ratios are not the
same, circulating currents will flow in the secondaries with no or
little load, and the division of load will be improper.
3. Percent impedance, including primary and secondary leads to each
transformer, should be nearly equal. If the impedance's are equal and
the turns ratios are identical, the paralleled transformers will
divide the load currents (properly) in proportion to their kVA
ratings. If the percent impedance's are different, the transformer
with the lower percent impedance will take more than its proper share
of the load.
On 2/5/07 1:29 AM, in article
I don't know your or your employer's background, but you are asking for
professional engineering advice that, legally, can be given only by licensed
engineers. Moreover, if your company is in the business of advising clients,
they need to have true expertise on the subject.
-- Fermez le Bush--about two years to go.
Theoretically yes you can operate in parallel if the transformer
impedances are equal when expressed on a common MVA base and the turns
ratio are identical, also the angle of displacement between pri and
sec need to be identical.
In practice however, would it be wise to parallel transformers of such
disparity? I would seriously consider changing both transformers to
12.5MVA with an emergency rating of 25MVA should one be offline.
You can get reasonable prices for secondhand transformers nowadays so
the existing ones could be sold to offset the investment.
That may be true in some countries but not all. In many countries there
is no such thing as a "licenced engineer". In many countries, electrical
installations are set up (I won't say designed) and run by those who
have had no formal engineering training or education at all.
That may be worth thinking about when choosing a room overseas - or
boarding a ferry or other passenger vessel.
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