a brief introduction to transformers
DESCRIPTION
A Brief Introduction to Transformers. Transformer Construction. Three-Phase Transformer. Transformer Action -- DC. Opposes battery voltage. Opposes flux buildup. Transformer Action -- AC. Voltage ratio = Turns ratio. “No-Load” Condition. “No load” condition continued. I o = I fe + I M - PowerPoint PPT PresentationTRANSCRIPT
A Brief Introduction to Transformers
ECE 201 Circuit Theory 1 1
Transformer Construction
2ECE 201 Circuit Theory 1
Three-Phase Transformer
3ECE 201 Circuit Theory 1
Transformer Action -- DC
4ECE 201 Circuit Theory 1
ECE 201 Circuit Theory 1 5
11
de N
dt
2 2
de N
dt
Opposes battery voltage Opposes flux buildup
Transformer Action -- AC
6ECE 201 Circuit Theory 1
max
max
max
sin
6.28
4.44
p p
p p
p p
prms p
dE N
dtd
E N tdt
E fN
E N f
max
max
max
sin
6.28
4.44
s s
s s
s s
srms s
dE N
dtd
E N tdt
E fN
E N f
7ECE 201 Circuit Theory 1
max
max
4.444.44
p p p
s s s
E N f NE N f N
Voltage ratio = Turns ratio
8ECE 201 Circuit Theory 1
“No-Load” Condition
9ECE 201 Circuit Theory 1
“No load” condition continued
Io = Ife + IM
Io = exciting current
Io provides the “magnetizing flux” and the “core loss”
Ife = core-loss current Ife = VT / Rfe
IM = magnetizing current IM = VT / jXM10ECE 201 Circuit Theory 1
Component Fluxes – Loaded Transformer
11ECE 201 Circuit Theory 1
ΦP = net flux in window of primary ΦS = net flux in window of secondary
Φlp = leakage flux of primary Φls = leakage flux of secondary
ΦM = mutual flux
ΦP = ΦM + Φlp
ΦS = ΦM – Φls
12ECE 201 Circuit Theory 1