Tuolla
paremmilla elektroniikkafoorumeilla ollaan kuitenkin sitä mieltä, että kanttiaaltoinvertteri ja läppäri = nou nou not hyvä.
Jos ei muuta, niin ainakin kone ottaa turpiinsa, kestoikä lyhenee tai taivaalta tippuu saavillinen ankeriaita. Jokainenhan uskoo täällä annettuja suosituksia ja ongelmavapauslausekkeita ihan oman mielensä mukkaan. On kuitenkin olemassa muunkinlaista käsitystä asiasta kuin tämän foorumin käsitys asiasta.
Sitten yhden invertterivalmistajan käsitys asiasta, joka on sen suuntainen että tietsikat tykkäis kanttiaallosta. Samasta lähteestä tulee jonkinlainen järjellinen selityskin sille, miksi tietyt moottorit eivät ehkä lähde käyntiin kanttiaaltoinvertterillä.
Q: What is the difference between
sine wave and
modified sine wave?
A: Alternating current (AC) has a continuously varying voltage that swings from positive to negative. This has great advantages in power transmission over long distances. Power from your power company is carefully regulated to be a perfect sine wave, because that is what naturally comes out of a generator, and also because sine waves radiate the least amount of radio power during long distance transmission.
On the other hand, a sine wave is expensive to make in an inverter, and many sine wave techniques use heavy, inefficient transformers. The most inexpensive way to make AC is to switch the DC on and off--a square wave. A modified sine wave is scientifically designed to simulate a sine wave in the most important respects so that it will work for most appliances. It consists of a flat plateau of positive voltage, dropping abruptly to zero for a while, then dropping again to a flat plateau of negative voltage, back to zero for a while, then returning to the positive voltage. This pause at zero volts puts more power into the 60HZ fundamental than a simple square wave does, so it is called "modified sine wave" instead of "square wave." Because the MOSFETs only have to turn completely on and completely off the dissipate he least amount of heat for the power generated, and so smaller semiconductors and heat sinks are needed than if you were trying to generate a real sine wave.
Q: Can I use a modified sine wave inverter for my medical equipment?
A: For Medical equipment, oxygen generators, etc. talk to the manufacturer of the equipment. PowerStream inverters are never tested or rated with medical equipment, and we don't guarantee that they will work to save your life. For such applications please find inverters that are rated and tested for such applications.
Q: What about square wave inverters?
A: These old-fashioned inverters are the cheapest to make, but the hardest to use. They just flip the voltage from plus to minus creating a square waveform. They are not very efficient because the square wave has a lot of power in higher harmonics that cannot be used by many appliances. Synchronous motors, for example, use the 60Hz component and turn the rest of the frequencies into heat. The modified sine wave is designed to minimize the power in the harmonics while still being cheap to make.
Q: How do I know if I need a sine wave, or if I can live with a modified sine wave?
A: The following gadgets work well with a modified sine wave: electric blankets, computers, motor-driven appliances, toasters, coffee makers, most stereos, ink jet printers, refrigerators, TVs, VCRs, many microwave ovens, etc.
Appliances that are known to have problems with the modified sine wave are some digital clocks, some battery chargers, most light dimmers, some battery operated gadgets that recharge in an AC receptacle, some chargers for hand tools (Makita is known to have this problem in the past). In the case of hand tools, the
problem chargers usually have a warning label stating that dangerous voltages are present at the battery terminals when charging. We would like to add to this FAQ any appliances that you have had trouble with, or had success with, using modified sine wave inverters.
