Losses in Machines Equations and Formulas
The following formulas and equations can be used to calculate and measure the different kinds of losses in an electrical machine such as eddy current and hysteresis as iron core losses and armature and field losses as copper losses.
Copper Losses:
Armature Loss:
Armature Cu Losses = Pa = Ia2 Ra
Where
- Ia is the armature current
- Ra is the armature resistance
Field Loss:
Field Cu Losses = Pf = If2Rf
Where
- If is the field current
- Rf is the field resistance
For Shunt Field:
Where
- Ish is the shunt field current
- Rsh is the shunt field resistance
For Series Field:
Where
- Ise is the series field current
- Rse is the series field resistance
Related Posts:
Iron/Core Losses
Hysteresis Loss:
Where
- η = hysteresis or Steinmetz’s constant
- Bmax = maximum value of the magnetic flux density
- f = frequency of magnetization
- V= volume of the core
Also
Where
- P is the number of poles
- N is the speed in RPM
Eddy Current Loss:
or
We = PB2max f2t2 Watts
Where
- Ke is the electrical constant of the core material
- Bmax is the maximum flux density
- f is the frequency of magnetization
- t is the thickness of lamination
- V is the volume of the core
Brush Losses in DC Machine:
PBD = VBD x Ia
Where:
- PBD = Power loss due to brush drop
- VBD = Voltage drop due to brush drop
- Ia = Armature Current
Other machinal loss and stray loss in a machine depends on multiple factors and different for each case and machine such as transformer, motor, alternator etc.
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