Motor Basics

Motor Basics
AGSM 325

Motors vs Engines
• Motors convert electrical energy to mechanical energy. • Engines convert chemical energy to mechanical energy.


• Advantages
– – – – – – – – Low Initial Cost - $/Hp Simple & Efficient Operation Compact Size – cubic inches/Hp Long Life – 30,000 to 50,000 hours Low Noise No Exhaust Emissions Withstand high temporary overloads Automatic/Remote Start & Control

• Disadvantages
– Portability – Speed Control – No Demand Charge

Magnetic Induction
• Simple Electromagnet

• Like Poles Repel • Opposite Poles Attract


Operating Principle

Motor Parts
• • • • • • Enclosure Stator Rotor Bearings Conduit Box Eye Bolt


• Holds parts together • Helps with heat dissipation • In some cases, protects internal components from the environment.

Stator (Windings)
• “Stationary” part of the motor sometimes referred to as “the windings”. • Slotted cores made of thin sections of soft iron are wound with insulated copper wire to form one or more pairs of magnetic poles.


• “Rotating” part of the motor. • Magnetic field from the stator induces an opposing magnetic field onto the rotor causing the rotor to “push” away from the stator field.

Wound Rotor Motors
• Older motor designed to operate at “variable speed” • Advantages
– Speed Control, High Starting Torque, Low Starting Current

• Disadvantages
– Expensive, High Maintenance, Low Efficiency


• Sleeve Bearings
– – – – Standard on most motors Quiet Horizontal shafts only Oil lubricated

• Ball (Roller) Bearings
– Support shaft in any position – Grease lubricated – Many come sealed requiring no maintenance

Other Parts
• Conduit Box
– Point of connection of electrical power to the motor’s stator windings.

• Eye Bolt
– Used to lift heavy motors with a hoist or crane to prevent motor...