Bryant ASPAS1BBA015 - Manual (Page 26)

Page 26
SECTION 2.1
DESCRIPTION & COMPONENTS
PART 2
AC GENERATORS
INTRODUCTION
The air-cooled, pre-packaged automatic standby
system is an easy to install, fully enclosed and self-
sufficient electric power system. It is designed
especially for homeowners, but may be used in other
applications as well. On occurrence of a utility power
failure, this high performance system will (a) crank
and start automatically, and (b) automatically transfer
electrical loads to generator AC output.
The generator revolving field (rotor) is driven by an
air-cooled engine at about 3600 rpm.
The generator may be used to supply electrical power
for the operation of 120 and/or 240 volts, 1phase, 60
Hz, AC loads.
A 2-pole, "V-Type", prepackaged transfer switch is
shipped with the unit (see Part 3). Prepackaged
transfer switches do not include an "intelligence
circuit" of their own. Instead, automatic startup,
transfer, running, retransfer and shutdown operations
are controlled by a solid state circuit board in the
generator control panel.
ENGINE-GENERATOR DRIVE SYSTEM
The generator revolving field is driven by an air-
cooled, horizontal crankshaft engine. The generator is
directly coupled to the engine crankshaft (see Figure
1), and mounted in an enclosure. Both the engine and
generator rotor are driven at approximately 3600 rpm,
to provide a 60 Hz AC output.
THE AC GENERATOR
Figure 1 shows the major components of the AC
generator.
ROTOR ASSEMBLY
The 2-pole rotor must be operated at 3600 rpm to
supply a 60 Hertz AC frequency. The term "2-pole"
means the rotor has a single north magnetic pole and
a single south magnetic pole. As the rotor rotates, its
lines of magnetic flux cut across the stator assembly
windings and a voltage is induced into the stator
windings. The rotor shaft mounts a positive (+) and a
negative (-) slip ring, with the positive (+) slip ring
nearest the rear bearing carrier. The rotor bearing is
pressed onto the end of the rotor shaft. The tapered
rotor shaft is mounted to a tapered crankshaft and is
held in place with a single through bolt.
Figure 1. AC Generator Exploded View