DC Generators
• Equivalent circuit
• Field circuit:
• Radj – adjustable external resistor to control field current
• RF - Resistor and inductor representing field coils which
produces flux in the generator
• LF
• Armature circuit
• EA – ideal voltage source
• RA – Resistance in armature
circuit EA
• VBrush – brush voltage drop
,• Simplified equivalent circuit
• RF,adj - combining both (RF and Radj)
• VBrush - left out if not too critical, otherwise
is approximated and added to RA
, • Magnetization curve of a DC generator:
• EA = K∅𝑤, ֜ EA ∝ ∅𝑤
• Field current, IF, produces mmf, F = NFIF,
(NFIF which in turn produces flux , ∅, in the machine)
• Since, IF ∝ NFIF ∝ ∅; and EA ∝ ∅,
• Then: Magnetization curve of a generator is normally
plotted as: EA versus IF
• Equivalent circuit
• Field circuit:
• Radj – adjustable external resistor to control field current
• RF - Resistor and inductor representing field coils which
produces flux in the generator
• LF
• Armature circuit
• EA – ideal voltage source
• RA – Resistance in armature
circuit EA
• VBrush – brush voltage drop
,• Simplified equivalent circuit
• RF,adj - combining both (RF and Radj)
• VBrush - left out if not too critical, otherwise
is approximated and added to RA
, • Magnetization curve of a DC generator:
• EA = K∅𝑤, ֜ EA ∝ ∅𝑤
• Field current, IF, produces mmf, F = NFIF,
(NFIF which in turn produces flux , ∅, in the machine)
• Since, IF ∝ NFIF ∝ ∅; and EA ∝ ∅,
• Then: Magnetization curve of a generator is normally
plotted as: EA versus IF
