Generac Power Systems 53187 - Manual (Page 8)

SECTION 1.2
HOW A GENERATOR WORKS
1
PARTI
THE REVOLVING FIELD AC GENERATOR
Operational Analysis- Units with 10 inch Stator Laminations
NO TE: See "IDENTIFYING UNIT S BY STATO R DIAM ETER" on Page 1.1-1.
Generator Operation m ay be briefly described as
follow s:
CZl
The ROTOR is attached to the engine PTO shaft
and rotates at the sam e speed as the engine.
□ As the Rotor turns, its m agnetic lines of flux cut
across the stationary coils of (a) a stator excitation
w inding and (b) dual stator AC pow er w indings. A
voltage is induced into these stationary w indings.
□ Current flow from the Stator excitation w inding is
delivered to the Voltage Regulator as unregulated
alternating current.
□ Current flow from the Stator AC pow er w indings is
delivered to connected electrical loads.
□ Sensing leads deliver a signal of ACTUAL pow er
w inding output voltage to the Voltage Regulator,
from the Stator AC pow er w indings.
□ The Voltage Regulator electronically com pares the
ACTUAL pow er w inding voltage to a REFERENCE
voltage w hich w as pre-set.
□ If the ACTUAL pow er w inding voltage is less than the
Regulator’s REFERENCE voltage. Regulator action
w ill (a) change the excitation w inding output to direct
current (DC), and (b) increase the excitation current
flow to the Rotor.
□ If the ACTUAL pow er w inding voltage is m ore than
the Regulator’s REFERENCE voltage, regulator ac­
tion w ill (a) change the excitation current to direct
current, and (b) decrease excitation current to the
Rotor.
□ The regulated direct current flow to the Rotor is
delivered via brushes and slip rings.
□ A regulated voltage is induced into the Stator AC
pow er w indings as the Voltage Regulator acts to
m aintain an ACTUAL voltage as close as possible to
an adjusted REFERENCE voltage.
A = EXCITATION W INDING
B = STATOR AC POW ER W INDING
C = STATOR AC POW ER W INDING
CB1 = MAIN CIRCUIT BREAKERS
CB4 = EXCITATION CIRCUIT BREAKER
TP = THERMAL PROTECTOR
Figure 5. Operating Diagram - Units w ith 10 Inch Stator Lam inations
PAGE 1.2-2