Power Inverter Output Waveforms
Residential power inverters are primarily available in two types of output current waveforms, pure sine and modified waves. Pure sine dc to ac power inverters output a smooth wave of electricity similar to the output wave of electricity you will find from the electricity company. Modified sine output wave is more of square wave of electricity that most electronics will not be able to identify as a different current, but some sensitive equipment might and not function properly. I strongly suggest doing the proper research before purchasing your dc to ac power inverter for your off grid system. Most standard North American electronics will function normally if the output voltage remains between 105 volts and 125 volts modified output waveform could have fluctuations between these levels. PSW or pure sine wave inverters will hold a more constant voltage. DC to AC power inverter use a line-frequency transformer to perform the voltage transformation the close you get to true sine output waveform the low the frequency of current transforming.
Pure sine wave dc to ac power inverter are available in a large array of wattages and quality output waveform levels. These types of power inverter output more than three step gradual wave form which although is not perfectly smooth it is extremely clean and reliable. If you are setting up a off grid system that needs to power audio or medical equipment this is type of output waveform you should be looking to use. With these types of electronics if steps in output wave are too frequent the functionality will not function. Another important aspect will be the lower level of harmonic distortion in the output wave which will be essential for audio equipment. High levels of harmonic distortion will result in poor sound quality. When using medical equipment low step counts in you output wave could cause the devices to turn off. Obviously when dealing with a machine that help monitor or regulate vitals it is important to properly research your system. Now obviously if you classify a power inverter as a pure sine power inverter the only requirement is that the output wave needs to be great than three steps per cycle but the higher quality units go far beyond these minimal levels, inquire about the quality wave prior to purchasing.
Modified sine wave dc to ac power inverters output more square wave with three or less steps in the waveform. There are many benefits in using this type of power inverter the obvious one is that cost per unit will be far less than its counterpart pure sine waveform units. If your using the a inverter in a off grid system with standard residential electronics this might be the right option for you. Most standard electronics are not able to detect the differences in the waveform and will function perfectly with this type of waveform. With elevated harmonic distortion levels if you are using a motor with a MSW or modified sine wave inverters then you might hear a little noise but the motor will cycle properly. The best way to know if a MSW inverter will work with your device is consult the manufacturer of set device, because each piece of equipment is so different it would be hard to get a 100% guarantee that it will work with knowledge of the exact specifications. Some modified sine wave inverters are not able to handle inductive loads. Inductive loads are commonly found in devices with heating elements such as microwave, coffee machines and kettles. Make sure the inverter you purchase can handle these loads if you desire to use them with this type of device, otherwise the electronic will work but the heating element will not get hot. With square wave inverter the line-frequency transformer inside the unit will perform very frequent spikes in it waveform very different from a pure or true sine waveform.
Power inverter output waveforms range from two very extreme levels, make sure you select the right type of unit for you and be cautious not to purchase a unit with too high a line frequency for your device. At the same time you do not necessarily need to go out a purchase the highest level of true sine wave power inverter as you will find the cost to be great and not required. True or pure sine wave power inverters are normally two to three times the cost of the modified sine wave inverter, and if the low frequency is not required to run your device then you might be wasting your money. The cost is not the only factor you might want to consider when selecting your inverter, conventionally modified sine wave power inverters have more durable interior circuitry. If you are setting up a system in a mobile application such as truck or bus a more durable MSW unit might make more sense. You might want to properly consult a professional to help you select the right dc to ac power inverter, pure sine wave or modified sine wave inverters.