Power Tech Generators PT-8KSI-2 Operator's Manual page 23

GENERATOR ASSEMBLY INFORMATION
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.
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
low voltage that air conditioning will have more difficulty in starting, and long starting
lines may overload generator and trip circuit breakers.
EXCITER FIELD COIL VOLTAGE SOURCE
Field coil DC voltage is obtained by rectifying the voltage from the phase to
neutral line of the generator output, or either appropriate terminal to provide the needed
voltage reference.
The rectifier bridge is an internal part of the static regulator. The static regulator senses
a change in the generator output and automatically regulates current flow in the exciter
field coil circuit to increase or decrease the exciter field strength. An adjustable rheostat
sized to be compatible with the regulator is used to provide adjustment of the regulator
sensing circuit.
The rotating field assembly consists basically of four members: 1) the shaft
assembly, 2) the core assembly, 3) the field coil damper windings, and 4) balance lugs
to provide a high degree of static
VOLTAGE CONNECTION
ROTATING FIELD ASSEMBLY (ROTOR)
PT-8/10/12KSI-2 Operators Manual
Generating Power to the World
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