Generac Power Systems GP Series Diagnostic Repair Manual page 12

Section 2 Direct Excitation (Brush Type)
The regulator changes the AC from the excitation
winding to DC. In addition, based on the Wire S15 and
Wire S16 sensing signals, it regulates the flow of direct
current to the rotor. The rectified and regulated current
flow from the regulator is delivered to the rotor windings,
via Wire 4, and the positive brush and slip ring. This
excitation current flows through the rotor windings and
through the negative (-) slip ring and brush on Wire 0.
The greater the current flow through the rotor windings,
the more concentrated the lines of flux around the rotor
become. The more concentrated the lines of flux around
the rotor that cut across the stationary stator windings,
the greater the voltage that is induced into the stator
windings.
Some generators have color coded wires. Always use
the appropriate schematic and wiring diagram for unit.
Initially, the AC power winding voltage sensed by the
regulator is low. The regulator reacts by increasing the
flow of excitation current to the rotor until voltage
increases to a desired level. The regulator then maintains
the desired voltage. For example, if voltage exceeds the
desired level, the regulator will decrease the flow of
excitation current. Conversely, if voltage drops below the
desired level, the regulator responds by increasing the
flow of excitation current.
4 (+) RED
0 (-) WHITE
VOLTAGE REGULATOR
6
AC Power Winding Output
A regulated voltage is induced into the stator AC power
windings. When electrical loads are connected across
the AC power windings to complete the circuit, current
can flow in the circuit.
AVR SENSING
C1 FEMALE
NOT USED
Figure 2-3. Alternator Configuration B
TO LOAD
MLB = MAIN LINE
MLB
CIRCUIT BREAKER
240 VAC
120 VAC 120 VAC
STATOR
POWER
WINDING WINDING
MAGNETIC
FIELD
ENGINE -
DIRECT ROTOR
DRIVE
MAGNETIC
FIELD
STATOR
EXCITATION
WINDING
Figure 2-2. Generator Operating Diagram
S15 2
WHITE BLUE
S16 6
GREEN BLUE
C1 MALE
RED (R2 – 22)
BLUE (R1 – 11)
BROWN (L2 – 44)
WHITE (L1 – 33)
POWER WINDING
BROWN
WHITE
L1 L2
TERMINAL BLOCK
44
(BLACK)
33
(WHITE)
TO PANEL
SENSING
STATOR
POWER
- +
AUTOMATIC
VOLTAGE
REGULATOR
003818
DPE
RED
BLUE
R1 R2
22
(WHITE)
11
(RED)
004966
Diagnostic Repair Manual