09-06-2012, 02:15 PM
Four Quadrant operation of DC Drives
DC Drives.ppt (Size: 3.77 MB / Downloads: 45)
4Q OPERATION: LIFT SYSTEM
Convention
Upward motion of the cage: Positive speed
Weight of the empty cage < Counterweight
Weight of the full-loaded cage > Counterweight
Introduction to electric braking
Braking of Electrical motor is frequently
employed to perform following operation.
(1)To stop a running motor
(2) To stop and run the motor in reverse
direction
(3) To limit the speed of the motor when
it is over hauled by an active load
Comparison of Electrical braking with Mechanical Braking
Mechanical braking cause wear and tear
Electrical braking is smooth and free from wear and tear.
Mechanical breakings are used along with electric braking as a back up protection to avoid accident in case of failure of electric
Braking .
Types of electric braking
In Braking , the motor works as generator
developing a negative torque which opposes
the motion.
There are three types of electric braking
(1) Regenerative Braking
(2) Dynamic braking
(3) Plugging