Whether you call this an AC Drive, Inverter Drive or Variable Speed Drive, the IMO SD1 series Inverter is the ultimate variable speed drive IMO Inverter, offering a range from 0.4kW to 110kW in 8 frame sizes. The IMO SD1 series Inverter is the first complete range of variable speed drives from IMO to offer STO (Safe Torque Off) (SIL2/SIL3).