Voltage Stabilizer for CNC

Hi. I have a large (5x10) Biesse CNC that I purchased used and have installed in my shop. The CNC power is supplied through a transformer that came with the CNC that steps up voltage to 400V. We have 3 phase 208 Delta wye in our shop and the CNC crashes when we turn on our dust collector (15hp). We put a multimeter on the CNC (after the transformer) and the voltage drops to 360 when the dust collector is turned on. We believe that we need a voltage stabilizer. I am still doing the math but I think we need a 20 KVA stabilizer. Since the power goes immediately into a transformer we don't need the voltage transformed in the stabilizer. Is voltage transformation mandatory in stabilizers or will I be able to find one that has a VI of 208 and VO of 208? Not a big deal as the transformer can be transformed from a variety of voltages. Almost everything I am seeing on the internet is Chinese or Indian stabilizers available through AliExpress or Indiamart. Not necessarily a problem but can anyone suggest a us retailer where I won't have to deal with importing/tarrifs? Thanks in advance.