Electrical motor controls

Once the proper motor is selected, understanding the many various control devices available and
their uses and limitations becomes an important part related to reliable operation and protection of
the motor and the personnel using the motor.
Motor Control Topics
There are four major motor control topics or categories to consider. Each of these has several
subcategories and sometimes the subcategories overlap to some extent. Certain pieces of motor
control equipment can accomplish multiple functions from each of the topics or categories.
C The four categories include:

1) Starting the Motor
                      Disconnecting Means
                      Across the Line Starting
                      Reduced Voltage Starting
2) Motor Protection
                      Over-current Protection
                      Overload Protection
                      Other Protection (voltage, phase, etc)
                      Environment
3) Stopping the Motor
                      Coasting
                      Electrical Braking
                      Mechanical Braking
4) Motor Operational Control
                      Speed Control
                      Reversing
                      Jogging
                      Sequence Control
• An understanding of each of these areas is necessary to effectively apply motor control
principles and equipment to effectively operate and protect a motor.