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GENERATOR INFORMATION
USE OF ELEGTRIC 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 are 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 as 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 as
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
general, the current reqnired to start 115-Volt motors connected
to medium slllI1ing loads will he approximately as follows:
MOTOR SIZE
AMPS FOR
AMPS FOR'
(HP)
RUNNING
{~TARTIN~l
(AMPERES)
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.S'
1/2
7.2
14.4
to
29.2'
3/4
10.2
20.4
to
40.S'
1
13
26
to
52
*NDTE: In the above table the maximum Amps for Starting is
more for some s111nlll1wtors than for lJ2rger ones. The reason
for this is tim! the hardest starting types (split-phase) are not
made in lJ2rger 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, tum
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 ampere meter is not insralled to monitor voltage
and load, check it with a pOltable meter and amp probe.
NOTE: When the vessel in which the generator is installed
contains AC equipment of 120 volts only, it is recommended
tim! the generator's AC tenninalblock be configured to pro-
vide one 120 volt AC hot leg for the vessel's distribution
panel. This will ensure good I1wtDr sta.ting response from the
generator.
Generator Frequency Adjustment
Frequency is a direct result of engine/generator speed, as
indicated by 111e following:
• When the generator is run at 1800 RPM, theAC voltage
output frequency is 60 Hertz.
• When the generator is run.at 1500 RPM, theAC voltage
output frequency is 50 Hertz.
Therefore, to change the generator's frequency/voltage,
the
generator's drive engine's speed must be changed using 111e
dipswitch on the ECU. The AC output configuration of 111e
generator changed and the connections on the voltage
sensing PC board changed.
Generator Maintenance
• Maintaining reasonable cleanliness is important
Connections of tenninal boards and rectifiers may
become corroded, and insulation surfaces may start con-
ducting if salts, dust, engine exhaust, carbon, etc. are
allowed to build up. Clogged ventilation openings may
cause excessive heating and reduced life of windings.
• For unusually severe conditions, thin rust-inhibiting petro-
leum-base coatings, should be sprayed or brushed over all
surfaces to reduce rusting and corrosion. 'TYpical materials
suggested are Daubert Chemical Co. "Non-RustAC-
410" and Ashland "Tectyle 506" or equivalent.
• In addition to periodic cleaning, the generator should be
inspected for (a) tightness of all connections,
(b)
evidence
of overheated terminals and (c) loose or damaged wires.
• The drive discs on single bearing generators should be
checked periodically if possible for tightness of screws
and for any evidence of incipient cracking failure. Discs
should not be allowed to become rusty because rust may
accelerate cracking. The bolts which fasten the drive disc
to the generator shaft must be hardened steel SAE grade
8, identified by 6 radial marks, one at each of the 6 cor-
ners of the head.
• The rear armature bearing is lubricated and sealed; no
maintenance is required. However, if the bearing becomes
noisy or rough-sounding, have it replaced.
• 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 OCCUlTed.
Repair Il).ust be made quickly or major components will
rub and cause major damage to generator.
...-N"
WESTERBEKE
Engines
&
Generators
35
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