Electrical Machines
LSEGG216A9080V
Transformer Transformer OperationOperation
Week 2Week 2
IntroductionIntroduction
• Basic operation• AS/NZS symbols• Types Step-up, Step-down, Isolation
Transformer Transformer OperationOperation
V+ CIVILCIVIL
Voltage Current
Magnetic Flux
Transformer Transformer OperationOperation
Applied Voltage
Induced Voltage
Induced Voltage in Secondary
Resultant Current
V1
V’1V’2
IM
Induced VoltageInduced Voltage
• Φmax =Maximum instantaneous flux• F = Frequency• N = Number of turns• Bmax = Maximum permissible flux density in Wb• A = CSA of core in m2
fN44.4V max AfNB44.4V max
Transformer Transformer OperationOperation
V1
IM
Ie
Io
Ie= Iron loss currentIo = No load current
Transformer Transformer OperationOperation
V1
V’1V’2
Io
I’2
I’1
I1
Transformer Transformer OperationOperation
V1
V’1V’2
Io
I’2 I’1
I1
Transformation Transformation RatioRatio
Magnetic flux is common coils
fN44.4V max
Therefore the voltage can be varied by changing the number of turns
Transformation Transformation RatioRatio
V1= N1
N2V2== k = Transformation Ratio
Transformation Transformation RatioRatio
V1x I1
N1
N2
= V2 x I2
=I1
I2
Transformation Transformation RatioRatio
V1x I1
VA
V2 x I2
kVAPower In Power Out
Transformation Transformation RatioRatio
V1x I1V2 x I2
200
200V 100V
800
K = 2
Transformer Basic Transformer Basic TestsTests• Open Circuit Test• Short Circuit Test• Oil Tests• Electrical Insulation• Polarity• Continuity
Open Circuit TestOpen Circuit TestUsed to determine Iron Losses
Supply = Rated Voltage
Open Circuit TestOpen Circuit Test
Wattmeter reading
V1
IMIo
Ie
Supply Voltage
Ammeter reading
Short Circuit TestShort Circuit TestUsed to determine Copper Losses
Supply Adjusted = Rated Secondary Current
Top Related