4.2
PRINCIPLES OF OPERATION
The power inverter converts power in two stages. The first stage is a DC-to-DC conversion process that raises the
low voltage DC at the inverter input to 145 volts DC. The second stage is the actual inverter stage that converts the
high voltage DC into 110 volts, 60 Hz AC, Modified Sine Wave (MSW). MSW is a waveform that has
characteristics similar to the sine wave shape of utility power. This type of waveform is suitable for most AC loads,
including linear and switching power supplies used in electronic equipment, transformers, and motors. The
modified sine wave produced by the power inverter has an RMS (root mean square) voltage of 110 volts, which is
the same as standard household power. Most AC voltmeters (both digital and analog) are calibrated for RMS
voltage under the assumption that the waveform measured will be a pure sine wave. These meters will NOT READ
the RMS voltage of a modified sine wave correctly. They will read about 20 to 30 volts low when measuring the
output of the power inverter. For accurate measurement of the output voltage of this unit, use a voltmeter marked
“TRUE RMS”. Figure
5
compares a Modified Sine Wave with a True Sine Wave.
The Power Inverter is incorporated into the Power City main unit. It
*
s DC source is the main unit
*
s 12 volt, 19AH
battery. Power is provided to the inverter through two flat contacts on the bottom of the inverter. The inverter
operates on stored energy in the main battery. With a full charge on the main battery, the inverter will supply a load
of 100 watts for approximately one hour and
5
minutes. Lower wattage loads will operate longer, higher wattage
loads will operate for a shorter time using energy from the main battery.
When the inverter is operated away from the main unit, the power source must provide between 11 and 14.5 volts
DC and must be able to supply the necessary current (amps) to operate the load. The power source may be a battery
or a well-regulated DC power supply. To obtain a rough estimate of the current (in amperes) that the power source
must deliver, simply divide the power consumption of the load (in watts AC) by 10.
Example: If a load is rated at 100 watts AC, the power source must be able to deliver:
100 / 10 = l0 amperes
CAUTION:
The inverter must be connected only to batteries with a nominal output voltage of 12 volts. The unit
will not operate from a 6 volt battery and will sustain permanent damage if connected to a 24 volt battery.
The inverter may be used whether or not the vehicle’s engine is running. However, the inverter may not operate
while the engine is starting since the battery voltage can drop substantially during engine cranking. The inverter
draws less than 0.06 ampere from the battery when it is not supplying power to a load.
4.3
CONNECTING INVERTER TO POWER SOURCE AWAY FROM
MAIN UNIT
The Inverter can be used away from the main unit by removing
it
from it
*
s mounting on the main unit and powering
it
from the Inverter power cable, located in the storage compartment in the back of unit. The power inverter has two
flat metal contacts that normally mate with the connector on the main unit. These flat contacts are connected to the
inverter power cable (black and red color) when the inverter is removed from the unit and operated away from the
unit. The inverter power cable comes equipped with a 12 volt DC plug. The tip of the p lug is positive and the side
contact is negative. Connect the power inverter to the power source by inserting the DC plug firmly into the
accessory outlet of a vehicle or other DC power source. The connection to the accessory outlet can be improved by
slightly rotating the plug in the socket. (See Figures 6 and 7)
Содержание Power City VEC029ACY
Страница 1: ......
