1/10/2025
DC Generator
Prepared By:
Engr. Renante D Junto REE,MTM
Technological University of the Philippines Taguig
Instructor
Principle of Generator Action
DC generator converts mechanical energy into electrical energy.
When a conductor move in a magnetic field in such a way
conductors cuts across a magnetic flux of lines and e.m.f. produces
in a generator and it is defined by faradays law of electromagnetic
induction e.m.f. causes current to flow if the conductor circuit is
closed.
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
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1/10/2025
Faradays Law
Faraday’s law basically states,
“when the magnetic flux or
the magnetic field changes with
time, the electromotive force is
produced”.
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
3
Lenz’s Law
Lenz’s law basically states, “the direction of the
generated voltage in the coil is such that it tends to
produce a current flowing opposing change of flux
through the coil.
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
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2
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Fleming Right Hand Rule
•The Thumb represents the direction of Motion of the
conductor.
• The First finger (four finger) represents Field.
• The Second finger (Middle finger) represents Current
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
5
How the Voltage generated
Presence of magnetic
lines of force
Motion of Conductors
cutting the flux
Magnetic field :- Permanent Magnet
(or)
Electro Magnet (practical)
Conductor : Copper (or) Aluminum bars placed in
slots cut around the periphery of cylindrical rotor
Relative motion:-
By Prime Mover
Turbine
I.C Engine (Internal combustion)
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
6
3
1/10/2025
Generated Voltage Equation
Eg - total generated voltage
𝜙 - flux per pole, maxwell
P - number of poles, even number
N - speed of armature, revolution per minute
Z - total number of armature conductors effectively used to add a resulting voltage
a - number of armature paths connected in parallel( determine by armature
winding)
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
7
Sample Problem 1
Thirty six dry cell are connected in four parallel groups
of nine series per group. If the voltage and rating of
each cell is 1.45 volts and 4 amp respectively. (a)
Calculate the voltage current and power, rating of the
entire combination? (b) recalculate the problem for
nine parallel groupsof four cells in series per group.
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
8
4
1/10/2025
Sample Problem 2
Calculate the average voltage generated in a
moving106 conductor if it cuts 2.5x106 maxwell in 1/40
seconds; in 1/80 seconds
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
9
Sample Problem 3
A six pole DC Generator has an armature winding with 504
conductors connected in six parallel paths. Calculate the
generated voltage in this machine if each pole produces 1.65 x
106 maxwell and the armature speed is 1800 rpm.
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
10
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1/10/2025
Sample Problem 3
A six pole DC Generator has an armature winding with 504
conductors connected in 2 parallel paths. Calculate the armature
speed in this machine if each pole produces 1.65 x 106 maxwell and
the generated voltage is 250 volts.
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
11
Sample Problem 5
Calculate the voltage generated by a four pole DC Machine given
the following particulars: Number of slots in armature=55 ; number
of conductors per slot =4; flux per pole=2.62 x 106 maxwells; speed
1200 rpm; number of parallel paths in armature=2
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
12
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1/10/2025
Sample Problem 6
If the armature winding of sample problem 5 had four
parallel paths, What would have been the generated
voltage?
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
13
Sample Problem 7
A four pole Machine generates 250 volts when operated at 1500
RPM. If the flux per pole is 1.85 x106 maxwells, The number of the
armature slots is 45, and the armature winding has two parallel
paths, Calculate (a) the total number of armature conductors, b
the number of conductors in each slot
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
14
7
1/10/2025
Sample Problem 8
How many total conductors and conductors per slot
would be necessary in the armature of problem 2-7. if
the winding had four parallel paths?
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
15
Sample Problem 9
At what speed is an armature rotating in a 12 pole machine if the
frequency in the armature conductors is 50 cps?
Technological University of the
Engr. Renante D. Junto REE Introduction of DC Generator
Phils. Taguig
16
