Motor control systems
Different kinds of motor control solution are compared in the following tables.
|Type||Is/In||Ts/Tn||Speed control||Torque control||Pros||Cons|
|Direct on line||5-10||5-10||No||No||Reduced cost, high starting torque||High in-rush current|
|Star – Delta||2-3||1-2||No||No||Reduced in-rush current||Reduced starting torque|
|Auto-transformer||2-3||1-2||No||No||Reduced in-rush current||High weight|
|Soft starter||3-5||1.5-2.5||No||Yes||Reduced in-rush current, controlled start and stop||Reduced starting torque|
|Variable speed drive||1.5||1.5-2||Yes||Yes||Controlled speed, Energy saving at reduced speed||Higher cost|