What are 3-phase voltage regulators used for, help me out if you know? Thank you!

Can be widely used in industry, agriculture, transportation, post and telecommunications, military, railroads, scientific research and culture and other areas of large-scale electromechanical equipment, metal processing equipment, production lines, construction equipment, elevators, medical equipment, air conditioning, broadcasting and television and household appliances, and other places that need a voltage regulator. Shanghai Meitian electrical appliances is specialized in the production of these companies, not bad