Understanding Transformer Power Measurements with Open Circuit Experiment

[nhrock3]

http://i44.tinypic.com/142zgg5.jpg

they say that we can measure aM and R_c

they say that in a good transformer the power waisted on R_1
is much smaller then on R_c
then we can neglect the power on R_c
so the power measured on the power meter will be the power on R_c

http://i39.tinypic.com/20zpcvm.jpg

why
aM=L_c
?
if we measure the voltage threw those to points
we need to know the current to get z_eq
and i don't have short circuit citiation here

 

[berkeman]

http://i44.tinypic.com/142zgg5.jpg

they say that we can measure aM and R_c

they say that in a good transformer the power waisted on R_1
is much smaller then on R_c
then we can neglect the power on R_c
so the power measured on the power meter will be the power on R_c

http://i39.tinypic.com/20zpcvm.jpg

why
aM=L_c
?
if we measure the voltage threw those to points
we need to know the current to get z_eq
and i don't have short circuit citiation here

I think they are just asserting that aM = L_c. I don't know why they labelled it aM in the first place. It's the magnetizing inductance of the transformer, I would think, in parallel with the transformed load resistance.

 

[nhrock3]

i posted it in the wrong sub forum
damn i am tired
please move it to tech

 

[berkeman]

No worries, thread moved. Are they just making a definition for us to use?

 

[nhrock3]

no they just say that from the total impedance we could know aM

but i don't know how?

 

[berkeman]

no they just say that from the total impedance we could know aM

but i don't know how?

What does aM stand for anyway?