Motor control application guide

Typical applications

• Centrifugal rotary pumps
• Fans with normal inertia
• Motor-generator sets
• Sanders
• Grinders
• Circular saws
• Pulp grinders
• Shapers and planers
• Lathes
• Milling machines

Load conditions

Normal starting torque. For continuous duty. Load fluctuations are infrequent. Has some capacity to handle minor, occasional overloads. Likely to draw less than 300% FLA on a reduced voltage start.

NEMA-preferred motor design

NEMA Design B: Low starting current, normal torque, normal slip.

Typical applications

• Reciprocating, positive displacement pumps
• Air compressors
• Refrigeration compressors
• Conveyors
• Crushers without flywheels
• Dough mixers
• Hammer mills
• Ball mills
• Turntables
• Car pullers

Load conditions

Heavy starting torque. Continuous or intermittent duty. Has some overload capacity. May draw more than 300% FLA.

NEMA-preferred motor design

NEMA Design C: Low starting current, high breakaway torque, normal slip.

Typical applications

• Hoists, lifts and cranes
• Elevators
• Machine tools
• Punch presses
• Crushers with flywheels
• High inertia flywheels

Load conditions

High starting torque. Intermittent or reversing service, plugging service, heavy or fluctuating loads. Likely to draw well over 300% FLA at starting.

NEMA-preferred motor design

NEMA Design D: High starting current, high breakaway torque, high slip.