Electric Motors

Electrical Energy Equipment: Electric Motors

ELECTRIC MOTORS

1. INTRODUCTION..........................................................................................................1 2. TYPES OF ELECTRIC MOTORS .........................................................................2 3. ASSESSMENT OF ELECTRIC MOTORS .......................................................10 4. ENERGY EFFICIENCY OPPORTUNITIES ...................................................14 5. OPTION CHECKLIST..............................................................................................21 6. WORKSHEETS ...........................................................................................................22 7. REFERENCES .............................................................................................................24 1. INTRODUCTION

This section describes the main features of the electric motors.

1.1 Where motors are used

An electric motor is an electromechanical device that converts electrical energy to mechanical energy. This mechanical energy is used for, for example, rotating a pump impeller, fan or blower, driving a compressor, lifting materials etc. Electric motors are used at home (mixer, drill, fan) and in industry. Electric motors are sometimes called the “work horses” of industry because it is estimated that motors use about 70% of the total electrical load in industry.

1.2 How a motor works

The general working mechanism is the same for all motors (Figure 1): An electric current in a magnetic field will experience a force. If the current carrying wire is bent into a loop, then the two sides of the loop, which are at right angle to the magnetic field, will experience forces in opposite directions. The pair of forces creates a turning torque to rotate the coil. Practical motors have several loops on an armature to provide a more uniform torque and the magnetic field is produced by electromagnet arrangement called the field coils. In...