Lister Petter LPP Series, Руководство оператора

Страница: 12 / 52

12
LPP PetRoL GeNset oPeRAtoRs' hANdbook
WAttAGe CALCULAtIoN
The biggest problem in selecting a generator is determining the power requirements
that must be met under operating conditions.
Under-sizing of the generator is the single most common mistake and can be
avoided by considering all the loads to be connected to the generator. Additionally,
calculating the starting requirements of any electric motor operated equipment is
a very important consideration.
An estimate of the total load that will be connected to the generator can be made
by getting the nameplate amperage of all equipment or tools to be used. The
nameplate, showing the electrical requirements, is found on all electric powered
tools, appliances, electric motors or devices. It lists such information as running
amperage, the speed at which the tool operates; hertz,or frequency; phase; and
for electric motors, the code specification.
Once the total amperage draw for all tools and equipment is known, the following
can be used to establish starting wattage required:
If the equipment is for heating or lighting and contains no electric motors, multiply
the running amperage requirement times 1, times the voltage rating or requirement.
The result will tell the wattage required for this application. Heaters, light bulbs,
coffee makers, hot plates, are refered to as resistive loads. This type of equipment
draws a constant amount of current while operating.
If the equipment to be powered consists of hand tools, such as saws, drills or
other, handheld type of equipment; multiply the running amperage times 2, times
the voltage requirement. Again, the result will tell the wattage required for this
application. These types of equipment typically draw twice their normal, free running
amperage when used at full capacity or when starting the motor.
If the equipment being run is stationary equipment or appliances containing electric
motors, multiply the running amperage times 3, times the voltage requirement.
Once again, the result will tell the wattage required for this application. Electric
motor driven stationary equipment typically requires up to three times the running
amperage when starting, until the machine’s motor comes up to operating
speed.
Generator wattage required = (amps) x (volts) x (1, 2, or 3)
This example will help to explain these requirements.
A customer wants to operate the following equipment on a generator:
(1) A Radiant Heater, (2) a Freezer, (3) a Small Refrigerator, (4) a Microwave Oven
and (5) Four sixty-watt light bulbs.
seLeCtING A GeNeRAtoR