Winter is near and I want to be able to run my Trane HVAC 1 hp motor and my Dell abd Mac desktop computers off an inverter or generator. Should I get something that puts out a pure sine wave or can I safely use less expensive, modified sine wave equipment?
the laptop wont care if its modified sine wave power but if you plan on running an ac get a generator the trane is using a 1 hp capacitor start capacitor run induction motor, it requires a true sinewave to run using modified will ruin it and void the waranty. also truesine inverters are very costly. you should be fine using a 25kw generator.
even though this is a single phase system there will be some harmonics. all systems are susceptible to them. they are however a more serious issue on 3 phase systems. most insidious are the 3rd order harmonics. inverters that are not true sine are themselves a source of harmonics and that being said so are generators. and a contributing factor to the harmonics problem on any system are non liner loads such as computers and other equipment that has a switching power supply. now if you wish to have a fully scale able inverter system that is able to be tailored to your needs. im using a system made of these one of these and one of these additional racks can be added for more capacity as needed just like the inverters may be paralleled as demand grows.
Pure sine is better; no harmonics. Modified sine (really a stepped approximation) is usually close enough and cheaper; it has much weaker harmonics than the old square-wave sources and the remaining ones don't generally cause problems.