Power Struggles At The Bank
It recently wasn’t reported, although it should have been. The culprit, an off brand Inverter named Dyna-moe, claiming superior performance. The power struggle ensued after an altercation between the heart of the system, Battery Bank & the newest of digital offensive boys, FlatScreen HD.
Although there were no fatalities this time, power source officials stated ” If we hadn’t shut the system down when we did, They all would have died a horrible death “. The death would have been a combination of excessive heat, fire & electrocution, due to breakdowns in the systems.
When a battery bank is being used, a component called the ” inverter ” stands between the bank & all of your electronic gadgets. The inverter changes the D.C.(direct current) voltage of the battery bank to an A.C.(alternating current) voltage, so modern appliances can be run.
Inverters vary in size & style, dependent upon the battery bank voltage & how much power you intend to draw from the bank. Commonly battery banks will be 12 volt / 24 volt d.c. or something similar, & the inverter will invert that voltage to 120 or 240 volts a.c., enabling you to power your electronic appliances.
The struggle mentioned earlier has to do with how the inverted power is changed. There are two types of inverters. Modified Sine Wave & True Sine Wave. Both have their satisfactory points & bad. Very delicate electronic equipment may require you to use the True Sine Wave type, whereas many items can be run with the Modified Sine Wave type.
Most modified sine inverters put out simple square waveforms, actually only two pulses, timed & width-modulated to be somewhat lined up in time as a sine wave would be. In other words, a modified sine wave inverter generates a blocky wave which has none of the smoothness of a sine wave, yet fewer harmonics than a simple square wave.
There are some modified sine inverters that put out simple stepped waveforms that come closer to sine, yet they are still “blocky”. Both of them attempt to filter out all of the unwanted harmonics with huge capacitors & or inductors. Neither ever attains the lack of harmonics that a true sine wave offers, & it’s the harmonics that are the nasty part.
A “true” sine wave inverter does exactly the same thing- it approximates an analog sine wave with digital steps, with the huge exception that it creates many, many digital steps instead of just two or four, & since the steps are correspondingly tiny, it’s super effortless to filter out any remaining harmonics with a simple filtering network- the result is an actual sine wave that approximates an analog sine wave well enough that no-one (and no equipment) has any issues with the result.
A simple fix for MSW (modified sine wave) inverters, is to run the output into a 1:1 transformer. The output will clean up & become a true sine wave. Normally the items, particularly battery chargers that do not contain a transformer, don’t like the rapid rise of a square wave. The magnetic properties of a transformer will smooth out the rapid voltage rise of the MSW. You will have some loss in the transformer, yet not as much as you might expect.
For every step in any progression there will be loss. It costs energy to alter energy, just as every mechanical advantage adds friction, requiring more energy to overcome the use of that medium. I didn’t think you wanted me to obtain into all that technical mumbo jumbo, I’ll just say there’s no such thing as perpetual power, excluding the sun.
Inverters vary in cost & can be found in every size imaginable. They can be purchased in electronic shops & automotive parts houses. Read all of the specs on the equipment you want to power & see if there are any recommendations as to the style of inverter you should use.
My rule of thumb (sounds stupid huh?) : If it’s expensive & delicate equipment you want to power, I would go with true sine wave, & if it’s not that critical an issue, modified sine wave inverters will usually do fine.
Rusty Garner-Smith
http://www.corrosionworks.net
02/10/2012
