Subject: Inverters, 2 of 5



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(3582)   Mon 29 Jul 91 12:50                             
By: Don Kulha
To: All

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Different Types of Inverters Inverters are manufactured in 3 
basic types. These types are named for the kind of power they 
produce. The question is, "How close does the inverter come to 
reproducing the waveform of standard commercial power?" There are 
trade-offs involved in inverter design. The more closely the 
inverter replicates commercial sinusoidal power, the less 
efficient the inverter becomes. This is a sad, but true, fact of 
physics. As the primary power source, efficiency is a very 
important factor in inverter operation. When we consider running 
large appliances such as freezers and washing machines on battery 
stored power, even small percentages of wasted energy are not 
acceptable. Battery stored energy is simply too expensive to 
waste. Square Wave Of all types of inverters, the square wave 
inverter produces power that least resembles commercial power. 
This inverter is the cheapest type to buy. It will not run many 
appliances which require cleaner forms of power. Stereos, 
televisions, computers, and other precision electronics will not 
accept square wave power. The power produced by square wave 
inverters varies considerably with the voltage changes of the 
batteries as they are discharged. These inverters are designed to 
be inexpensive, and as such their efficiency is low, less than 
70% when fully loaded. If the square wave inverter is only 
partially loaded, its efficiency drops to less than 30%. These 
inverter cost about $0.50 per watt and are available in sizes up 
to 1,000 watts. The square wave inverter is not suitable for 
homestead usage. It is neither efficient or versatile enough. 
Modified Square Wave The modified sine wave inverter represents a 
compromise between efficiency and utility. The modified sine wave 
inverter is the best type to use in home power service. This type 
of inverter is capable of powering almost all commercial 
electrical appliances, even very delicate electronics such as 
computers. The power this inverter produces is not identical to 
commercial power, but it is close enough to fool almost all 
appliances. The efficiency of the modified sine wave inverter is 
the highest of all types of inverters, in some cases consistently 
over 90%. For example, we use a 1,500 Watt Trace Inverter. This 
inverter is over 90% efficient at power output levels between 100 
and 600 watts. Its no load power consumption is less than 1 watt. 

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