Installation manual
GENERATOR
INFORMATION
USE
OF
ELECTRIC
MOTORS
The power required to start an electric motor is considerably
more than is required to keep
it
running after
it
is
started.
Some motors require much more current to start them than
others. Split-phase (AC) motors require more current to start,
under similar circumstances, than other types. They arc com-
monly used on easy-starting loads, such
as
washing
machines,
or
where loads are applied after the motor is
started, such as small power tools. Because they require 5 to
7
times
a'i much current to start as to run, their use should be
avoided, whenever possible,
if
the electric motor is to be dri-
ven
by a small generator. Capacitor and repulsion-induction
motors require from 2 to 4 times as much current to start
a<;
to run.
The
current required to start any motor varies with the
load connected to it. An electric motor connected to an air
compressor, for example,
will require more current than a
motor to
which
no load
is
connected.
In
geneml, the current required
to
start 115-
Volt
motors connected
to medium starting loads
will be approximately
a~
follows·
,.
MOTOR
SIZE
AMPS
FOR
AMPS
FOR
(HP)
RUNNING
STARTING
._--
(AMPERESJ
...
___
(AMPERES)
1/6
3.2
6.4
to
22.4'
1/4
4.6
9.2
to
32.2'
_.
_._-
1/3
5.2
10.4
to
72.8'
. -
--"'_
.
._-----
1/2
7.2
14.4
to
29.2'
3/4
10.2
20.4
to
40.8'
---
.-
1
13
26to
52
*NOTE:
III
the above table the maximum Amps for Starting is
more Jar
some
small motors than for larger ones. The reason
for this is
thaI the hardest starting types (split-phase) are not
made in larger sizes.
Because the heavy surge
of
current needed 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. If difficulty
is
experienced
in
starting motors, turn
off all
other
electrical loads and, if possible, reduce the load
on the electric motor.
Required
Operating
Speed
Run
the generator first with
no
load applied, then
at
half the
generator's capacity, and finally loaded to its full capacity as
indicted on the generator's data plate. The output
voltage
should be checked periodically to ensure proper operation
of
the generating plant and the appliances
it
supplies.
If
an
AC
voltmeter
or
ampmeter is not installed to monitor voltage and
load, check it with a portable meter and amp probe.
NOTE:
When the vessel
in
which the generator is installed
cOllfains
AC
equipment
of]
20 volts ollly,
it
is
recommended
that the generator:
..
AC
terminal block be configured to pro-
vide one 120 volt
AC
hOi
leg for the vessel:
..
distribution
panel. This will ensure good motor starting response from the
generator.
Generator
Frequency
Adjustment
Frequency
is
a direct result
of
engine/generator speed, as
indicated by the following:
o
When
the generator
is
run
at
1800
RPM,
the
AC voltage
output frequency
is
60 Hertz.
o
When
the
generator
is
run
at
1500 RPM,
the
AC voltage
output frequency
is
50 Hertz.
Therefore,
to
change the generator's frequency, the genera-
tor's drive engine's speed must be changed. Along with a
reconfiguring
of
the
AC output connections
at
the generator,
a regulator board voltage output adjustment must also be
made. Sec ELECTRONIC GOVERNOR
in
this manual.
Generator
Maintenance
D Maintaining reasonable cleanliness
is
important.
Connections
of
terminal boards and rectifiers may
become
corroded, and insulation surfaces may start conducting if
saits, dust, engine exhaust, carbon, etc. arc allowed to
build up.
Clogged ventilation openings may cause exces-
sive heating and reduced life
of
windings.
o For unusually severe conditions, thin rust-inhibiting petro-
leum-hase coatings, should he sprayed or brushed over
all
surfaces
to
reduce rusting and corrosion. Typical materials
suggested are Dauhert
Chemical Co. ·'Non-Rust AC-410"
and Ashland "lectylc
506"
or equivalent.
o
In
addition
to
periodic cleaning, the generator should be
inspected for (a) tightness
of
all
connections, (h) evidence
of
overheated terminals and (c) loose
or
damaged wires.
o The drive discs on single bearing generators should he
checked periodically if possihle for tightness
of
screws
and for any evidence
of
incipient cracking failure. Discs
should not he allowed to become rusty because rust may
accelerate cracking. The holts which
fa~ten
the drive disc
to the generator
shatt must be hardened steel
SAE
grade
8,
identified
by
6 radial marks, one
at
each
of
the 6 cor-
ners
of
the head.
o The rear annaturc bearing
is
lubricated and sealed; no
maintenance
is
required. However, if the bearing becomes
noisy
or
rough-sounding) have
it
replaced.
o Examine bearing
at
periodic intervals.
No
side movement
of
shaft should be detected when force
is
applied. if side
motion
is
detectable, bearings are wearing
or
wear on
shaft
of
bearing socket outside bearing has occurred.
Repair must be made quickly
or
major components will
rub and cause major damage
to
generator.
Engines & Generators
33