Answer / vivek

in a synchronous machine , there are three kinds of impedences

1. Xd - synchronous reactance ; (used in steady state
modelling )
a special case is salient pole machines where sync impedence
is split into direct axis impedence and quadrature axis
impedence , ie Xd and Xq . see double reactance theory for
more details
2. Xd' - transient reactance ;(used in transient modeling)
3. Xd'' - subtransient reactance .

all other machines have three kinds of impedences which are
used in power system modelling
1. positive sequence impedence
2. negative sequence impedence
3. zero sequence impedence

Answer / r

for a syn machine - syn impedance
fictious impedance
load impedance
normal case - input impedance
output impedance
transmission lines- surge impedance
load impedance

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