6
OPM-129/F
UNIT CAPABILITIES
GENERATOR CONNECTIONS
120 Volt and 240 Volt receptacles are provided for
connection to various loads. The diagram below represents
this 7,500 watt (starting output) generator. A & B represent
the 120 volt output legs of this generator. Up to 3,360 watts
at 120 volts (56 Amps) can be drawn from the receptacles
attached to either A or B output legs. This generator is
capable of producing 28 Amps of 240 volt current at C.
Check the appliance or tool nameplates for the current and
voltage to insure compatibility. Remember that power taken
from C reduces the power available at equally both A and B
and vice versa.
STARTING ELECTRIC MOTORS
Electric motors require much more current (amps) to start
them than to run them. Some motors, particularly low cost
split-phase motors, are very hard to start and require 5 to 7
times as much starting current as running current. Capacitor
motors are easier to start and usually require 2 to 4 times
as much starting current as running current. Repulsion
Induction motors are the easiest to start and require only 1
1/2 to 2 1/2 times as much starting as running current.
Most fractional horsepower motors take about the same
amount of current to run them whether they are Repulsion
Induction (RI), Capacitor (Cap), or Split-Phase (SP) type.
If the electric motor is connected to a hard starting load
such as an air compressor, it will require more starting
current. If it is connected to a light load, or no load such as
a power saw, it will require less starting current. The exact
requirement will also vary with the brand or design of the
motor.
Self-exciting generators respond to severe overloading
differently than utility power. When overloaded, the engine
is not able to supply enough power to bring the electric
motor up to operating speed. The generator responds with
high initial starting current, but the engine speed drops
sharply. The overload may stall the engine. If allowed to
operate at very low speeds, the electric motor starting
winding will burn out in a short time. The generator
winding might also be damaged.
CAUTION: EQUIPMENT DAMAGE
Running the generator set under these conditions may
result in damage to the generator stator as well as the
motor winding.
The heavy surge of current required for starting motors
is required for only an instant. The generator will not be
damaged if it can bring the motor up to speed in a few
seconds of time. If difficulty is experienced in starting
motors, turn all other electrical loads off and if possible
reduce the load on the electric motor.
