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CONTROLS, INDICATORS AND CONNECTORS
Figure 1 details the front panel, featuring the unit's 115 volt AC Outlet, ON/OFF
Power Switch and two LED indicators. The green LED indicates power and proper
operation of the inverter and the red LED indicates inverter shutdown from an over-
load or over-temperature fault. In addition to turning the unit ON and OFF, the
ON/OFF Power Switch can be used to force reset of the inverter circuits.
Power is supplied through a standard North American outlet that can accommodate
either two- or three-pin AC plugs.
Figure 1 Front Panel
115 VOLT AC
OUTLET
Figure 2 shows the back panel of the inverter, where the DC Power Connections and
high speed cooling fan are located.
Figure 2 Back Panel
NEGATIVE DC POWER
CONNECTION
HOW THIS INVERTER WORKS
The power inverter converts low voltage DC (direct current) from a battery or other
power source to standard 115 volt AC (alternating current) household power.
Principle of Operation
The 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 current into
115 volts, 60 Hz AC current.
12VDC to
145VDC
CONVERSION
12VDC
Internal
Input
Fuses
The DC-to-DC converter stage uses modern high frequency power conversion
techniques that have replaced the bulky transformers found in less technologically-
advanced models. The inverter stage uses advanced power MOSFET transistors in a
full bridge configuration. This ensures excellent overload capacity.
The Power Inverter Output Waveform
The AC output waveform of the Power Inverter is known as "modified sine wave." It
is a waveform that has characteristics similar to the sine wave shape of utility power.
INVERTER ON/OFF
POWER SWITCH
POWER LED
INDICATOR
FAULT LED
INDICATOR
POSITIVE DC POWER
CONNECTION
HIGH SPEED COOLING FAN
145VDC to
115VAC
CONVERSION
AC
115VAC, 60Hz
Outlet
to AC appliances
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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 115 volts, which is the same as standard household power. Most
AC voltmeters (both digital and analog) are sensitive to the average value of the
waveform rather than the RMS value. They 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 inverter. For accurate measurement
of the output voltage of this unit, use a true RMS reading voltmeter such as a Fluke
179, Fluke 79 III series, Beckman 4410, or Triplett 4200.
Modified Sine Wave and Sine Wave Comparison
PROTECTIVE FEATURES OF THE INVERTER
The Power Inverter monitors the following potentially hazardous conditions:
Low Battery Voltage — This condition is not harmful to the inverter, but could damage the
power source. An alarm will sound and the Inverter automatically shuts down when input
voltage drops below 10.7 volts. When the condition is corrected, the inverter will
auomatically restart.
Over Voltage Protection — The Power Inverter will automatically shutdown when the
input voltage exceeds 15.0 volts DC.
Overload Protection — The unit will automatically shut down when the continuous
draw exceeds the 225 watts. Reduce the load and manually reset using the inverter's
ON/OFF Power Switch.
Over Temperature Protection — If the temperature inside the Power Inverter reaches
150°F, the unit will automatically shut down. Allow the unit to cool for at least 15
minutes before restarting after a heat-related shutdown. Unplug the unit while cooling.
If the Fault LED lights when the battery is fully charged, follow the steps outlined in the
"Troubleshooting" section of this User's Manual. The Fault LED will light if there is an
excessive voltage drop between the battery and the inverter.
Note:
Reverse polarity or short circuit condition may cause external or internal fuses
to open and may cause irreversible damage to the Power Inverter. Take extra
care to ensure a proper polarity hook-up.
INSTALLATION AND OPERATING INSTRUCTIONS
Power Source Requirements
The power source must provide a nominal voltage of 12.8 volts DC and must be able
to supply the necessary current 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) 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 225 watts AC, the power source must be able to deliver:
225 divided by 10 = 22.5 amperes.
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