Parallel operation of transformers

Sir,
In our plant we have got 2MVA,11/0.433 KV,Dyn11,Percentage imp 5% TFR and 1.MVA,11/0.415 KV,Dyn11,TFR with percentage impedence 6.5%.

I would like to operate these two tfrs in parallel.At present 2 MVA tfe is running with 85% load and 1.5 MVA tfe is running with 60% load. We just need the 1.5 MVA tfr to share another 10% or 20% load from 2 MVA tfr.Can we make the secondary voltages equal by adjusting the tap changers and synchronize both the transformers.

Kindly guide.
T.Sriram
9179094929
 
Responding to Sriram's 11-Feb-09 (08:00) query... the answer is yes!

1) If TR1 is the 2.0 MVA transformer, and TR1 the 1.5 MVA unit, then when paralleled, TR1 will carry about 56.5 percent of the combined load (2.6MVA), and TR2 about 43.5 percent. That is each will carry about 75 percent of their rating!

2) Tap adjustment will reduce circulating current to a tolerable level!

Regards, Phil Corso ([email protected])
 
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