text: <s>[INST] Single Isolation Transformer Multiple VFDs Summary: Has anyone ever use one big isolation tranformer to feed a panel with multiple VFDs?I have a panel with 11 1HP, 2 3HP, and 1 15HP PF525 drives and I want to use one isolation transformer to protect the power grid from the harmonics generated by the VFDs. I don't have room for individual line reactors and I'm not worried about protecting the drives from noise on the grid. Has anyone ever tried this? Would I just add up the KW ratings of all the drives? [/INST] i have done it with large drives and I did add up the KVA of each drive. you may also want to consider whether or not all drives are on at the same time etc. so that you may be able to get away with a smaller xfmr. keep in mind that even with an isolation xfmr the harmonics will still be quite high for six pulse diode front end drives. MTE and Arteche make some passive as well as active harmonic filters that should get you down to the 5% THD range. \\n </s>