6-1
6. Generator
GENERATOR DESCRIPTION
These are vertical-shaft, 2-bearing, belt-driven,
2-pole, revolving field generators with brushes and
slip rings (Figure 6-1). Output voltage is regulated
by microcontroller-based genset controller A1
(Page 5-1).
Stator
The stator consists of steel laminations with two or
three sets of windings in the lamination slots. The
main windings (T1–T2, etc.) power the connected
loads and the quadrature windings (Q1–Q2) supply
power for the generator field. Some models have
battery charging windings (B1–B2). See the Fig-
ure 6-3 schematics.
Rotor
The rotor consists of a shaft with steel laminations
wrapped with field windings. A molded slip ring as-
sembly is pressed on to supply field current to the
rotor windings through the brush block assembly.
The rotor shaft is supported on both ends by sealed
ball bearings and is driven by a belt pulley.
Genset Cooling Fan
The genset cooling fan (blower) is bolted to the gen-
erator drive pulley to cool generator and engine.
Brush Block
Field current passes through the brush block which
has two spring-loaded carbon brushes that make
contact with the rotor slip rings.
Voltage Regulator
Genset controller A1 maintains constant output volt-
age under varying load conditions by varying field
current. Power for field excitation is supplied by the
quadrature winding (Q1–Q2).
Line Circuit Breakers
Line circuit breakers (CB1 / CB2 / CB3) are mounted
on the control panel to protect the generator leads
and provide a means for disconnecting the genera-
tor from the load. See the Figure 6-3 schematics.
Principle of Operation
During startup the controller enables field flashing
by means of battery current for fast buildup of gener-
ator voltage as the engine accelerates to operating
speed. During operation, the controller maintains
nominal AC output voltage by varying field current in
response to load. In response to transient loads, it
lowers the voltage setpoint to allow engine recov-
ery. The quadrature windings supply field power
through the controller.
GENERATOR SERVICE
The generator brush block, end bell and stator (Fig-
ure 7-2) can be removed from the top of the genera-
tor/engine base, leaving the rotor in place. It is nec-
essary to remove the rotor drive pulley before the
rotor can be pulled up out of the base. To remove the
rotor drive pulley see Section 7. Drive Belt System.
Stator Removal
1. Remove the two-piece control enclosure (Sec-
tion 5. Control) and disconnect the stator leads
from the line circuit breakers and neutral
(grounded) terminal on the base.
2. Remove the brush block (Page 6-3).
CAUTION
The brushes can be damaged if
the brush block is not removed before re-
moving the end bell.
3. Remove the generator/engine bracket.
4. Remove the four generator through bolts.
5. Pull the generator end bell straight up.
6. Pull the stator assembly straight up, taking care
not to damage rotor or stator windings.
Stator Reassembly
Reassembly is the reverse of removal. Align the sta-
tor so that the leads exit through the slot in the base.
Relubricate the bearing bore in the end bell with mo-
lybdenum disulfide paste or equivalent. Make sure
the wave washer and O-ring are in place in the bear-
ing bore. Torque the through bolts to 8 lb-ft
(11 N-m).
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