Section 2.1 - Description And Components; Introduction; Engine-Generator Drive System; Alternator Assembly - Generac Power Systems 7 kW NG Repair Manual

Section 2.1
Description and Components

INTRODUCTION

The alternator contained within the Generator is a revolving field
(rotor) type with a stationary armature (stator), and excitation
to the field provided through brushes and slip rings (direct
excitation). The Generator may be used to supply electrical
power for the operation of 120 and/or 240 VAC, 1-phase, 60
Hz, AC loads.

ENGINE-GENERATOR DRIVE SYSTEM

The air-cooled engine is directly coupled to the rotor internally.
Both the engine and the rotor operate at 3600 rpm to provide a
60 HZ AC output.

ALTERNATOR ASSEMBLY

The standard alternator consists of three basic components;
a rotor, stator, and brush assembly.
provides the magnetic field which will induce a voltage into the
stator assembly. The brush assembly provides the electrical
connection to the rotor, which allows for excitation voltage and
current to create the needed magnetic field.
Rotor
Operating the 2-pole rotor at 3600 rpm will supply a 60 HZ AC
frequency. The term "2-pole" means the rotor has a single
north magnetic pole and a single south magnetic pole. Held in
place with a single through bolt, the tapered rotor shaft mounts
to the tapered crankshaft of the engine. As the rotor rotates its
lines of magnetic flux cut across the stator assembly windings
and induces a voltage into the stator windings. The rotor shaft
has a positive and negative slip ring, with the positive slip ring
nearest the rear-bearing carrier. The bearing is pressed onto the
end of the rotor shaft.
SLIP RINGS
BEARING
Figure 38. Rotor
Stator
The stator houses a dual power winding and an excitation
winding. Coming from the stator there are Eight (8) stator leads
as shown in Figure 39.
An adapter molded into the engine block and a rear-bearing
carrier support the stator can. Four stator bolts connect the
rear bearing carrier and the stator can to the engine.
Page 40
The rotor assembly
Brush Holder and Brushes
Attached to the rear-bearing carrier, the brush holder and
brushes allow for the electrical connection to the rotor. Positive
and negative brushes are retained in the brush holder, with the
positive brush riding on the slip ring nearest the rotor bearing.
Wire 4 connects to the positive brush and Wire 0 to the negative
brush. Wire 0 also connects to the frame ground. The rotor
windings receive rectified and regulated excitation current (DC)
through Wire 4, as well as current from a field boost circuit.
The current flow creates a magnetic field around the rotor
having a flux concentration that is proportional to the amount
of current flow.
Located within the Generator control panel enclosure are the
Nexus controller, connection points, SCR, and Main Line Circuit
Breaker (MLCB).
PART 2
CLOSEST TO
STATOR
BEARING
BA
4
0
44
11
2 6
TO C1 SEE TABLE FOR PINOUT
Figure 39. Stator Output Leads
4
- +
Figure 40. Brush Holder and Brushes

OTHER AC GENERATOR COMPONENTS

AC GENERATORS
CONFIGURATION A
C1
PIN #
44 1 44
11 2 11
6 3 6
2 4 2
22
4 5 4
33
0 6 0
44
11
CONFIGURATION B
C1
PIN #
44
11 44 1 44
11 2 11
6
2 6 3 6
2 4 2
4
0 5
6
4 4
0 0
0