Don energy efficient motors have to be oversized because they don develop enough starting torque?
The same minimum allowable locked rotor (starting) torque is specified by NEMA for all Design A and B motors regardless of efficiency. NEMA standards for Design E motor locked rotor torque are higher than Designs A and B levels for some horsepower and speed combinations and lower for others. While some energy efficient motors may exhibit a slightly lower locked rotor torque than their standard-efficiency counterparts, no problems should be posed except for special applications such as heavily loaded conveyors. NEMA Design C motors should probably be specified for such applications anyway. Full-load, breakdown and locked rotor torque values are available for most energy efficient and standard motor models within the MotorMaster+ Electric Motor Selection software.
