Motor Selection Considerations

  Torque and speed are the two primary considerations in choosing a motor for a particular application.

Motor manufacturers’ data that are usually available to users include the following specifications:

• Mechanical Specifications
– Mechanical time constant
– Speed at rated load
– Rated torque
– Frictional torque
– Dimensions and weight
– No-load speed
– No-load acceleration
– Rated output power
– Damping constant

– Armature moment of inertia

• Electrical Specifications
– Electrical time constant
– Armature resistance and inductance
– Compatible drive circuit specifications (voltage, current,
etc.)
– Input power

– Field resistance and inductance

• General Specifications
– Brush life and motor life
– Heat transfer characteristics
– Coupling methods
– Efficiency
– Mounting configuration
– Operating temperature and other environmental conditions