Advanced motor-control techniques are a practical necessity because they enable more efficient and quieter appliances. In the past, these advanced control techniques were only available as proprietary solutions, and hence were limited in scope to a few high-end appliances.
Standard MOVs (metal oxide varistors) have been providing transient voltage surge protection from surges for many years. These surges can originate from lightning, electronic switching, electromagnetically induced surges and a myriad of other sources. MOVs are specifically designed to protect electronic equipment from overvoltage transient surges however they are not designed to protect the same equipment from a temporary abnormal overvoltage.
