dynamic braking


Also found in: Wikipedia.

dynamic braking

[dī¦nam·ik ′brāk·iŋ]
(mechanics)
A technique of electric braking in which the retarding force is supplied by the same machine that originally was the driving motor.

Dynamic braking

A technique for braking in which mechanical energy is converted to heat or electrical energy in order to slow or stop motion. An all-mechanical dynamic brake consists of rotating vanes that circulate a viscous fluid in a manner that generates heat. This is one way that the power of the wind is harnessed for space heating. An electric dynamic brake consists of an electric dynamo in which the mechanical energy is converted to electric form, and either converted to heat in a resistor or returned to the supply lines. Typically, electric braking is accomplished with the same machine that serves as the drive motor. Electric dynamic braking is employed in electric vehicles, elevators, and other electrically driven devices that start and stop frequently. See Wind power

The most common type of dynamic braking will be explained for a direct-current (dc) motor. To accomplish braking action, the supply voltage is removed from the armature of the motor but not from the field. The armature is then connected across a resistor. The electromotive force generated by the machine, now acting as a generator driven by the mechanical system, forces current in the reverse direction through the armature. Thus a torque is produced to oppose rotation, and the load decelerates as its energy is dissipated, mostly in the external resistor, but to some extent in core and copper losses of the machine. See Direct-current motor

Electric braking can also be accomplished by causing the energy of the rotating system to be converted in the armature to electrical energy and then returned to the supply lines. This mode of operation, called regenerative braking, occurs when the counterelectromotive force exceeds the supply voltage.

Interchanging two of the lines supplying a three-phase alternating-current (ac) induction motor also produces braking. In this case, called plugging, the direction of the electromagnetic torque on the rotor is reversed to cause deceleration. Both the energy of the system and the energy drawn from the supply lines are expended in copper and core losses in the machine as heat. The power lines must be disconnected when the rotor comes to rest. See Alternating-current generator, Electric power generation, Electric rotating machinery, Induction motor

References in periodicals archive ?
Tenders are invited for Dynamic Braking Resistor For Short Hood Roof Mounted Dbr Hatch Grid Resi8stance For Wdm3d Locos Drg No.
Dedicated stop and enable inputs are available, along with a dynamic braking feature that brings the motor to zero speed in a quick and controlled fashion.
offers spring-engaged, hydraulically disengaged caliper brakes for dynamic braking and static-holding applications.
The plug-in locomotive also can regenerate dynamic braking energy through a system provided by Brookville Equipment Company.
Full featured hydrostatics deliver power management, infinite speed control, power turns, counter-rotation and dynamic braking.
Cast steel flywheels warranted to a maximum speed of 900 rpm--which corresponded with a 65 mph road speed--were driven by V-belts to simulate the vehicle mass, and dynamometer dynamic braking was used to simulate road loads.
A third diesel locomotive will join the train to add dynamic braking.
Featuring integral dynamic braking as standard, the drive has the ability to absorb the energy created by fast stops, as in this case, whilst giving very smooth, precise control of off-the-shelf motors.
Next-generation LTO-3 improvements include the addition of a Graceful Dynamic Braking feature, which significantly reduces media stress and the likelihood of media damage in the event of a sudden loss of power to the drive.
A PID controller, DC injection braking and an integral dynamic braking transistor (IGBT) and resistor are all standard.
The ProBatter machine uses one submicro SCF drive for each axis, each equipped with the optional dynamic braking kit.
Pacesetter NEMA 4 Series AC variable frequency drives (VEDs) allow machinery builders to economically add the versatility of adjustable speed, dynamic braking and comprehensive motor protection to their products used in we or dusty environments.

Full browser ?