Westerbeke BTDA 15.0 Operator's Manual & Installation Manual page 74

Motor Starting Requirements
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 than
others. Split-phase (AC) motors require more current to start, under similar Circumstances,
than other types. They are commonly 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 driven 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 required to start 115-volt motors connected to medium starting
loads will be approximately as follows:
MOTOR SIZE AMPS FOR AMPS FOR
(HP)
RUNNING
STARTING
(Amperes) (Amperes)
110
3.2 6.4 to 22.4'
1/4
4.6 9.2 to 32.2'
1/"
5.2
10.4 to
{".Il·
1/,
I."
14.4 to
"!!."
"/4 lU."
"U.4
to
4U.1l
1
1;;
,0
to 52
figure 6.0.2: Startmg Loads
NOTE: In the above table the maximum "Amps for Starting" is more
for some small motors than for larger ones. The reason for this is that
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 H 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, H possible, reduce the load on the electric motor.
Westerbeke Generators 72
15.0KWBTDA