Problem Loads with Modified Square Wave Inverters

Take heed if you’re considering buying a modified square wave inverter to shave a few bucks off your system costs. A whole raft of modern appliances won’t run as well and some not at all on this waveform:

• Laser printers, photocopiers, and anything with an electrical component called a thyristor
• Anything with a silicon-controlled rectifier (SCR), like those used in some washing machine controls
• A few laptop computers
• Some fluorescent lights with electronic ballasts
• Some battery chargers for cordless tools
• Some new furnaces and pellet heaters with microprocessor controls
• Digital clocks with radios
• Appliances having speed/microprocessor controls (like some sewing machines)
• X-10 home automation systems
• Medical equipment such as oxygen concentrators

In general, because the total harmonic distortion is higher in modified square wave inverters, motors will run hotter (less efficiently), and likely not last as long. Additionally, a modified square wave inverter will often cause a “buzz” to be heard from audio devices and sometimes other appliances like ceiling fans and microwave ovens.