1. COMPUTE AND SEPARATE
THE LOSSES IN
DC SHUNT MACHINE
By N.Tejaswani

2. LOSSES MEANS…………
• The basic function of a dynamo is the
conversion of energy, either from mechanical
to electrical form or from electrical to
mechanical form. Whole of the input to the
dynamo is not converted into useful output
energy but a part of the input energy is
converted into heat and is lost for the useful
output purpose of the machine. The energy
converted into heat is called the ENERGY LOSS.

3. TYPES OF LOSSES……….
• Copper Losses or Electrical Losses
• Core Losses or Iron Losses
• Brush Losses
• Mechanical Losses
• Stray-Load Losses

4. COPPER OR ELECTRICAL LOSSES…
These losses are the winding losses because these
occurs in the winding of the machine.
Armature current losses= = Ia
2Ra
Copper losses in shunt field of a machine=Ish
2Rsh
Copper losses in interpole winding=Ia
2Ri
Copper losses in a series field machine=Ise
2Rse
Copper losses in a compensating
windings=Ia
2Rc

5. CORE LOSSES OR IRON LOSSES…
These losses are also called as magnetic losses.
These losses are constant about 20% of a full
load losses
Core losses are of two types
1. Hysteresis losses
2. Eddy current losses

6. BRUSH LOSSES…
Power loss at the brush contacts between the
copper commutator and the carbon brushes.

7. MECHANICAL LOSSES..
The losses associated with mechanical effects
are called as MECHANICAL LOSSES. They
consists of bearing friction loss and windage
loss.
These losses are usually very small.

8. STRAY LOSSES…
Stray losses are results from
1. The distortion of flux because of Armature
reaction
2. Short circuit currents in the coil, undergoing
commutation etc
Stray losses are assumed as 1% of full load
output power

9. ANY queries ……..?