TH750
HOW THESE INVERTERS WORK
Your inverter converts low voltage DC (direct current) electricity from a battery to 115 volt AC (alternating current)
household 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 converts the high voltage DC into 115 volts, 60 Hz AC.
Power Inverter Output Waveform
The AC output waveform of your inverter is known as a modified sine wave. It is a stepped 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 small motors.
The modified sine wave produced by this inverter has an RMS (root mean square) voltage of 115 volts. 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 correctly read the RMS voltage of a modified sine wave. Non-TRUE RMS meters will read
about 20 to 30 volts low when measuring the output of this inverter. For accurate measurement of the output voltage
of this unit, use a TRUE RMS reading voltmeter such as a Fluke 87, Fluke 8080A, Beckman 4410 or Triplett 4200.
115 VOLT AC OUTPUT
APPLIANCE POWER CONSUMPTION
Most electrical tools, appliances and electronic equipment have labels that show the unit’s power consumption in
amps, watts or both. To avoid inverter shutdown and possible damage to the inverter or equipment, do not exceed
the inverter’s wattage rating. To obtain a rough estimate of the current (in amperes) the power source must deliver
where the power consumption of the tool or device is given in watts AC, simply divide the power consumption of
the load by 10. For example, if a load is rated at 200 watts AC, the power source must be able to deliver: 200 divided
by 10 = 20 amperes.
Your inverter will operate most AC loads within its power rating. Some induction motors used in refrigerators,
freezers, pumps and other motor-operated equipment, require very high surge currents to start them. Your inverter
may not be able to start some of these motors even though their rated current draw is within specifications for this
power inverter.
If a motor refuses to start, observe the battery voltage using a DC voltmeter while trying to start the motor. If the
battery voltmeter drops below 11 volts while the inverter is attempting to start the motor, this may be why the motor
won’t start. Make sure the battery connections are tight and the power source battery (or batteries) is (are) fully-
charged. If the connections are good and the power source is charged, but the voltage still drops below 11 volts,
you may need to use a larger power source battery (or battery combination).
SINE WAVE
115V AC
MODIFIED
SINE WAVE
115V AC
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3
1
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6
1. Battery Clips
2. USB Charging Port
3. 115 volt AC three-prong outlets
4. Green Power LED
5. Red Fault LED
6. ON/OFF Switch
7. Grounding Post
8. Negative (–) DC Power Connection
9. High-Speed Cooling Fan
10. Positive (+) DC Power Connection
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7
10
9
Back of Unit
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5
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FEATURES
On the front panel are two LED indicators. The green LED indicates power and proper operation of the inverter; the
red LED indicates inverter shutdown from overload or over-temperature condition, or abnormal input voltages. The
ON/OFF Switch turns the inverter on and off. The switch can also be used to force reset of inverter circuits by
switching it off, then back on again.
120 volt AC power is supplied through standard North American three-prong type outlets. The outlets can
accommodate either two- or three-pin AC plugs.
Controls and Functions
TH225
TH400
5
6
2
4
4
1
7
1. Battery Clips
2. DC Accessory Outlet Plug
3. USB Charging Port
4. 115 volt AC three-prong outlets
5. Green Power LED
6. Red Fault LED
7. ON/OFF Switch
8. Positive (+) DC Power Connection
9. Negative (–) DC Power Connection
10. High-Speed Cooling Fan
11. Grounding Post
8
9
11
10
Back of Unit
3
2
4
4
1
1. Battery Clips
2. DC Accessory Outlet Plug
3. USB Charging Port
4. 115 volt AC three-prong outlet
5. Green Power LED
6. Red Fault LED
7. ON/OFF Switch
8. Grounding Post
9. Negative (–) DC Power Connection
10. High-Speed Cooling Fan
11. Positive (+) DC Power Connection
9
8
11
10
Back of Unit
5
6
7
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TH225_400_750_ManualENSPFR_051010.qxp 5/10/2010 2:27 PM Page 4
