Appendix A Generator Selection And Wattage Requirements - Kohler 13ERG Installation Manual

Appendix A Generator Selection and Wattage Requirements

General Wattage Requirements
Consider the total wattage requirements (lights, motors,
appliances) when selecting a generator set, or when
sizing wattage usage in which available space and
construction limit the size of the generator set.
Motor Loads
When figuring generator set capacity requirements for
loads that include electric motors, consider the high
current demanded by the motors during startup. The
inrush or starting current is typically 2 to 3 times higher
than that required when the motor reaches normal
operating speed. Allow a reserve for inrush demands
plus other loads that could be on the line as the electric
motor starts. Use Figure 1 as a guide when selecting
generator set capacity requirements involving motor
loads.
Starting
(Inrush)
Motor
HP
1/4
1/3
1/2
3/4
1
2
3
Figure 1 Motor Requirements
Voltage
Full load amps
Rated load amps
Locked rotor amps
Starting (inrush) watts
Running watts
Figure 2 Typical Air Conditioner Requirements (60 Hz)
TP-6335 9/04
Running
Watts
Watts
750 330
1000 400
1500 600
2000 750
3300 1100
4000 2000
5000 3000
7,000
115 230
9.3 4.8
7.7 4.0
34.0 20.0
3910 4600
886 920
Appliance Loads
Generator sets often furnish AC for appliances such as
TVs, stereos, and electric water heaters. Except for the
resistance-type loads such as the water heater, the
requirements for appliances are usually low. Do not
overlook such
requirements. Allow a reserve capacity for anticipated
appliance loads to avoid overloading a generator set.
Lighting Load
To calculate the lighting load, add the wattage of each
generator set-operated lamp. Note that not all of the
lights or lamps are on the generator set AC
circuit—some are DC powered by a 12-volt battery.
Ensure that the calculated total wattage includes only
lights actually on the generator set AC circuit.
Air Conditioners
The starting characteristics of air conditioners vary
greatly—for example, one 12,000 Btu unit has lower
starting requirements than a 10,000 Btu unit of another
variety. When using only one unit, there is usually no
starting problem provided that the lighting and appliance
load is not too high when starting the generator set.
Simultaneous starting of two air conditioning units,
however, can present problems if the generator set
capacity is marginal. Because of the variation in starting
characteristics among air conditioners, this publication
makes no statements regarding multiple-motor starting
capabilities of the generator set covered. Consider
delayed starting or the use of easy-starting devices on
air conditioner units whenever simultaneously starting
more than one motor.
See Figure 2 for typical air conditioner requirements.
The requirements vary among different manufacturers.
Air Conditioner Size (Btu)
9,000 12,000
115 230 115
9.9 5.0 11.8
7.0 3.5 8.9
40.0 20.0 50.0
4600 4600 5750
805 805 1020
loads when figuring
16,000
230 115 230
6.3 16.3 8.0
4.8 13.0 6.2
31.0 75.0 36.0
7130 8630 8280
1100 1500 1430
the total
24,000
230
11.6
10.2
56.0
12,900
2350
Appendix A-1