Motor Loads; Appliance Loads - Kohler 4CKM Operation And Installation Manual

Motor Loads

When figuring generator set capacity requirements for
installation involving motor loads, do not overlook the
high current demanded by the motor during start-up.
The " in-rush"or starting current may be 2-5 times higher
than that required when the motor reaches normal
operating speed. Reserve capacity must be allowed for
in-rush demands plus other loads which could be on the
line as the motor starts.
Air conditioning units are perhaps the most common
type of motor load for generator sets in recreational
vehicles. The starting characteristics of the different
makes of air conditioners vary greatly— one particular
13,500 Btu unit has, for example, lower starting
requirements than an 11,000 Btu unit of another make.
When only one unit is involved, there is usually no
starting problem, provided of course, the lighting and
appliance load is not too high when the unit is started.
The trend seems to be toward larger capacity air
conditioners and the use of more than one unit in larger
vehicles. Simultaneous starting of two units can present
problems if the capacity is marginal. Because of the
variation in starting characteristics of the various makes
of air conditioners, no definite statements are made in
this publication regarding multiple-motor starting
TP-5393 9/93
capabilities of the mobile generator sets covered.
Delayed starting or use of " easy starting"devices on air
conditioner units should be considered whenever
simultaneous starting of more than one motor is
involved. The starting and running requirements of
some motor loads common to mobile applications are
listed in Figure 6-1. Use this as a guide when selecting
generator set capacity requirements involving motor
loads. See Figure 6-2 for generator set capabilities
regarding air conditioners. Capabilities will vary
according to KILOWATT DERATING following. For
specific information regarding simultaneous starting of
two or more motors, contact Kohler Co., Generator
Division— Product Applications.

Appliance Loads

Generator sets in recreational vehicles are often used to
furnish AC for appliances such as TV, stereo, electric
water heaters, etc. With the exception of the resistance
type loads such as the water heater, requirements for
appliances are usually low. Such loads must not,
however, be overlooked
requirements. Reserve capacity should be available for
anticipated appliance loads to avoid overloading of a
set. The average power requirements of some electrical
appliances tools are listed in Figure 6-3 and Figure 6-4.
when figuring total
Installation 6-3