calculate transformer impedance
calculate transformer impedance
(OP)
How to find transformer impedance ( Delta- Y grounded transformer 12000V - 480V)?First , I calculate I2 using this formula -->I2= KVA(load)/Volt_left_side. After that, I calculate I1 using the formula , N1/N2 = I2/I1.
After that , I calculate Z2 = V2/I2. Next , I calculate Z1 using this formula --> N1/N2 = sqrt(Z1/Z2).
After found Z1 and Z2 , how to find the Ztransformer??I would like to get percentage of tranformer impedance.
After that , I calculate Z2 = V2/I2. Next , I calculate Z1 using this formula --> N1/N2 = sqrt(Z1/Z2).
After found Z1 and Z2 , how to find the Ztransformer??I would like to get percentage of tranformer impedance.






RE: calculate transformer impedance
Short secondary winding terminals
Apply low voltage to primary and increase until rated current circulates in secondary
Calculate ratio of applied voltage to rated voltage. x100 for percentage impedance
Read text book!
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RE: calculate transformer impedance
RE: calculate transformer impedance
Example: If it takes 10 VAC applied to a 120 VAC primary winding to produce the rated secondary current when the secondary is short circuited, the transformer impedance percentage would be 8.3333%.
I understand multiplying by 100 produces a percentage, but how is Vp/Vrated equal to an impedance. In my text books, impedance is always determined by the ratio of ac voltage divided by ac current. Please clear up my confusion over the use of this terminology - which is evidently commonly used in industry. (i.e., a tech note from Saftronics on variable frequency drives makes repetitive use of 2 or 3 % impedance ratings for power transformers.
Thanks for any and all elucidation.
RE: calculate transformer impedance
The voltage ratio Vp/Vr to produce 1 pu current is Vpu (per unit). The impedance in pu (Zpu) is Vpu/Ipu. Since Ipu is 1, Zpu is the same as Vpu.
RE: calculate transformer impedance
The short-circuit test is done during testing in the manufacturer's test lab and the X% impedance is something that established itself long before the ISO and other organisations decided that units shall reflect what we are measuring.
It fits quite well in pu thinking, though.
Gunnar Englund
www.gke.org
RE: calculate transformer impedance
Given transformer test data from the manufacturer i.e. load loss, % impedance, no-load loss, % exciting current. How can I calculate a series impedance and shunt admittance for modeling this transformer?
Thanks!