pro200-400w.qxp 4/30/2010 9:07 AM Page 19

OPERATING PRINCIPLES

For You Technical Types.

1. Basic Operating Principles:

WHISTLER inverters work in two stages. During the first stage, the DC to DC converter increases the DC input voltage from the power source (e.g. a 12 volt battery) to 145 volts DC. In the second stage, the high voltage DC is converted to 110 volts (60 Hz AC) using advanced power MOSFET transistors in a full bridge configuration. The result is excellent overload capability and the capacity to operate difficult reactive loads. The output waveform resulting from these conversions is a "quasi-sine wave" or a "modified sine wave" as shown on below.

This stepped waveform is similar to the power generated by utilities and has a broad range of applications.

The modified sine wave produced by the Inverter

The modified sine wave produced by your Whistler inverter has a root mean square (RMS) voltage of 110 volts.

OPERATING PRINCIPLES

The majority of AC voltmeters measure RMS voltage and assume that the measured waveform will be a pure sine wave.

Consequently, these meters will not read the RMS modified sine wave voltage correctly and, when measuring your WHISTLER inverter output, the meters will read about 20 to 30 volts too low. To accurately measure the output voltage of your inverter, use a true RMS reading voltmeter such as a Fluke 87, Fluke 8060A, Beckman 4410, Triplett 4200 or any multimeter identified as "True RMS."

For more information on inverters see our Inverter FAQ page.

A true sine wave typical of home AC outlet.

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Whistler PRO-200W, PRO-400W owner manual Operating Principles, Modified sine wave produced by the Inverter