Power Tech Generators PTS-30 Operator's Manual page 144

TM
Athlon generators are brushless, self excited or permanent magnet generator (PMG) excited,
synchronous AC generators. All units utilize sophisticated Automatic Voltage Regulators (AVR) to control
the output voltages and frequencies.
The self excited generator is made up of six major components: main stator (armature), main rotor (field),
exciter stator (field), exciter rotor (armature), rectifier assembly, and voltage regulator (AVR). The
adds the PMG excitation
PMG - Optional
PERMANENT
MAGNET
STATOR
PERM.
SHAFT
MAGNET
ROTOR
In the self excited units, the generator’'s exciter consists of a stationary field and a rotating armature. The
stationary field (exciter stator) is designed to be the primary source of the generator’'s residual magnetism.
This residual magnetism allows the exciter rotor (armature) to produce AC voltage even when the exciter
stator (field) is not powered. This AC voltage is rectified to DC by the rotating rectifier assembly and fed
directly to the main rotor (field). As the generator shaft continues to rotate, the main rotor (field) induces a
voltage into the generator's main stator (armature). At rated speed, the main stator’'s voltage produced by
the residual magnetism of the exciter allows the automatic voltage regulator to function. The regulator
provides voltage to the exciter field resulting in a build-up of generator terminal voltage. This system of
using residual magnetism eliminates the need for a special field flashing circuit in the regulator. After the
generator has established the initial residual voltage, the regulator provides a controlled DC field voltage
to the exciter stator resulting in a controlled generator terminal voltage.
In the standard configuration (shunt excited), the automatic voltage regulator receives both its input power
and voltage sensing from the generator's output terminals (See Figure 1). With the optional PMG
configuration, the regulator receives input power from the PMG. The regulator automatically monitors the
generator's output voltage against an internal reference set point and provides the necessary DC output
voltage to the exciter field required to maintain constant generator terminal voltage. Adjusting the
regulator’'s reference set point changes the generator’'s terminal voltage. Consult the regulator manual for
specific adjustment and operating instructions.
When a motor is started, the motor draws a large surge of current. This starting current is equivalent to
the motor s locked rotor or stall current and is 5 to 10 times normal full load current. When the generator
unit.
EXCITOR
STATOR
EXCITOR
SHAFT
ROTOR
1
AUTOMATIC
VOLTAGE
REGULATOR
ROTATING
SHAFT
RECTIFIER
PMG
OUTPUT
GENERATOR
STATOR POWER
GENERATOR
SHAFT
ROTOR