Generating Power to the World
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PTI-15/20-T4F Operators Manual
GENERATOR ASSEMBLY INFORMATION
EXCITER TYPE GENERATOR
The exciter pole pieces contain residual magnetism, which sets up lines of force
across the air gap to the exciter armature. When the exciter begins to rotate a voltage
is induced and current flow is initiated in the exciter armature AC windings. This voltage
is fed to the rotating rectifier assembly, rectified and fed to the alternator field, which
sets up lines of force across the air gap to the alternator stator windings and to the
output circuit. A static voltage regulator is connected to the generator output. The
regulator will rectify part of the output voltage to provide a DC voltage to the exciter field
coils. This will increase the density of the lines of force in the exciter, increasing the
voltage induced into the exciter armature windings, and therefore, to the rotating
rectifiers. The rotating rectifier output will be increased which increase the alternator
field strength and generator output will build up its rated voltage. Adjustment of the
generator output to the rated voltage level is accomplished by controlling the current fed
to the exciter field coils. Regulation is automatic with the static type voltage regulator.
An additional voltage adjustment range is provided if desired by turning the Voltage
Adjust Rheostat.
ELECTRONIC VOLTAGE REGULATION
Electronic Voltage Regulator (EVR) also referred to, as an Automatic Voltage
Regulator (AVR) is a very reliable device, which uses solid-state electronics to maintain
voltage accuracy at ±2% of the regulated voltage. The Voltage Regulator is designed to
automatically regulate and maintain the generated AC voltage throughout the load
range that is from no load to full load.
VOLTAGE CONNECTION
The generator may be connected at the terminal board to deliver 120/240 volts to
a 3 wire grounded neutral system.
If all equipment requires 120-volts then the 120-volt connection is preferred, even if
two lines leave the same switch box. The two lines at the inputs to the switch box are
both connected to the un-grounded 120-volt lines from the generator.
The 120-volt connection enables the Electronic Voltage Regulator (EVR) to hold the
voltage very close to the 115 or 120 volts, as initially adjusted, regardless of the power
distribution amount the different distribution lines. The 120-volt connection is
recommended if the entire electrical load requires only 115 or 120 volts. Although the
120/240-volt connection may also be used when all loads requires only 110 volts, it
should be pointed out that this connection, the 240-volts, is regulated and the lightly
loaded phase, or line, will deliver a high line to neutral voltage and the heavily loaded
phase will deliver a low line to neutral voltage. The heavily loaded line may have such a
