Generac Power Systems 53187 User Manual

Page 8

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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

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