Why does the intermediate frequency furnace start to burn out the household appliances?

The 6-pulse intermediate frequency furnace is a thyristor full-wave rectifier. During the working process, a large number of harmonics will be generated, especially the 5, 7, 11, and 13 harmonics are represented. The content is very high. These harmonics, Exceeding the standards for the safe use of household appliances, causing the household appliances to fail to work properly or even be damaged.