Home › Electrical Engineering Forum › General Discussion › what is % impedance of transformer? › Re: what is % impedance of transformer?

2011/04/15 at 1:01 pm
#11962

freak16

Participant

**The normal method
of expressing transformer impedance is as a percentage voltage drop in the
transformer at full-load current and this reflects the way in which it is seen by
system designers. For example, an impedance of 10% means that the voltage
drop at full-load current is 10% of the open-circuit voltage, or, alternatively,
neglecting any other impedance in the system, at 10 times full-load current, the
voltage drop in the transformer is equal to the total system voltage.**

**Formula written by MH is perfect.
**

Thenormalmethod

ofexpressingtransformerimpedanceisasapercentagevoltagedropinthe

transformeratfull-loadcurrentandthisreﬂectsthewayinwhichitisseenby

systemdesigners.Forexample,animpedanceof10%meansthatthevoltage

dropatfull-loadcurrentis10%oftheopen-circuitvoltage,or,alternatively,

neglectinganyotherimpedanceinthesystem,at10timesfull-loadcurrent,the

voltagedropinthetransformerisequaltothetotalsystemvoltage.Expressed

insymbolsthisis:

Vz %Z

IFLZ

E

100

ofexpressingtransformerimpedanceisasapercentagevoltagedropinthe

transformeratfull-loadcurrentandthisreﬂectsthewayinwhichitisseenby

systemdesigners.Forexample,animpedanceof10%meansthatthevoltage

dropatfull-loadcurrentis10%oftheopen-circuitvoltage,or,alternatively,

neglectinganyotherimpedanceinthesystem,at10timesfull-loadcurrent,the

voltagedropinthetransformerisequaltothetotalsystemvoltage.Expressed

insymbolsthisis:

Vz %Z

IFLZ

E

100