Inverter – Modified and Pure Sine

What is a power inverter?
A power inverter is a device that converts DC power (12 or 24 volt) into AC power (240volt). The AC power output is usually 230VAC, 50Hz.

How can an inverter be used?

With a large enough battery bank or alternator output from a vehicle almost anything can be powered from an inverter, assuming that the inverter has a high enough power output for the given load. Everyday appliances such as microwaves, power tools, TV’s and DVD players, lights, audio/visual equipment, battery chargers and computers are common loads. Sine Wave inverters on the other hand are ideal for running sensitive appliances. Brands such as Victron Energy, COTEK and Sinergex are all inverters designed to run sensitive test equipment such as communication equipment, scales, high end stereos and video equipment and communications equipment.

Modified Square Wave:

The most common, general-use inverters available on the market today are the Modified Sine.
Out of the Sine Wave” variety they are usually available at more moderate pricing compared to pure sine wave models. Modified Square Wave or better known as Modified Sine Wave are designed to have better characteristics than that of the outdated Square wave.
Designed to emulate the Pure Sine Wave output, Modified Sine Wave inverters do not offer the same perfect electrical output than that of the Pure Sine. As such, a negative by-product of the Modified output unit is the electrical noise, which can prevent these inverters from properly powering certain loads. For example, many T.V’s and stereos use power supplies incapable of eliminating common mode noise. As a result, powering such equipment with a Modified Sine Wave may cause “grain” or small amount of “snow” on your T.V picture or even a humming noise. Digital appliances with timing devices, light dimmers or variable speed devices such as late model microwaves may not work well or may not even work at all.
Modified Sine Inverters will power appliances such as power tools, kitchen appliances charging mobile phones, camera batteries and most T.V’s, DVD players.

Pure Sine Wave:

Pure Sine Wave Inverters are mandatory for powering any device that requires a sensitive load. Pure or True Sine Wave inverters provide power similar to the mains power you receive in your very own home or office at work. This is highly reliable and does not produce electrical noise interference associated with other types of inverters. Because this type of inverter has a “perfect “sine wave output, the power produced will reliably power your sensitive loads correctly with no interference. Some appliances which are likely to require Pure Sine Wave include computers, digital clocks, battery chargers, light dimmers, variable speed motors and audio/visual equipment. If your application is an important video presentation at work, running digital electronic appliances in your caravan or motor home, telecommunications application or any other sensitive loads, you must use a Pure Sine Wave inverter.

What size inverter do I need?

The power rating of the inverter you chose (in VA or Watts) is directly dependent on the load you will power. It is important that you select an inverter which is powerful enough to operate your specific loads.

Step1:
The first step in selecting your inverter is to calculate the total watts of all the appliances that you plan to power. Virtually all AC appliances will display a label, normally on the back of the appliance placed near where the power wire enters the unit. This will indicate how many Amps or Watts the equipment uses.

Step2:
The second step is to determine the characteristics of your load. AC loads normally fall into two categories. Electronic loads, such as switching power supplies (or SMPS, normally found in computers), and motors such as a compressor in a refrigerator. Both of these types of loads require different levels of the initial surge of power required to start up, normally referred to as Peak Surge. This is almost always considerably higher than the Continuous Load (which is the power needed to run the load after initial start up)and must be considered when sizing the inverter, the battery, and the cables that connect the two.

What are some safety precautions to keep in mind?

Improper use of a power inverter can result in serious injury. The inverter should not be installed under the bonnet in the engine bay of a motor vehicle. Keep the inverter free from moisture as liquids conduct electricity, which may lead to serious damage or injury!
Do not use the inverter near flammable materials or where fumes and gases accumulate.