Pure Sine Wave Inverter
This is the inverter type that produces 230 V alternating voltage at its output in a clean sine shape, equivalent to the mains. Its harmonic content is low, so the risk of heating, humming and faulty operation is markedly lower in devices with motors, electronic control and measurement functions.
A pure sine output is obtained by high-frequency switching followed by filtering. Because the resulting waveform resembles the mains, the power stage inside the device sees the conditions it expects.
The difference becomes especially clear with these loads: compressor refrigerators and air conditioners, tools containing induction motors, switch-mode adapters of rechargeable devices, medical devices and precision measuring equipment. With a stepped waveform these devices either heat up more or do not work at all.
On the RV side there is a second reason: electromagnetic noise. An inverter producing a distorted waveform can generate interference both in the vehicle radio and in systems using wireless control. The noise level of a pure sine inverter is usually lower, but it is still right to mount it away from antenna and signal cables. Its standby consumption is above that of a modified sine equivalent; the decision is made according to the type of devices you will run.
Context in which this term is used: Guide to automatic RV levelling