Ad
related to: vfd braking torque definition chart
Search results
Results from the WOW.Com Content Network
Additional braking torque can be obtained by adding a braking circuit (resistor controlled by a transistor) to dissipate the braking energy. With a four-quadrant rectifier (active front-end), the VFD is able to brake the load by applying a reverse torque and injecting the energy back to the AC line.
A braking chopper is an magnetical switch that limits the DC bus voltage by switching the braking energy to a resistor where the braking energy is converted to heat. Braking choppers are automatically activated when the actual DC bus voltage exceeds a specified level depending on the nominal voltage of the variable-frequency drive
Direct torque control (DTC) is one method used in variable-frequency drives to control the torque (and thus finally the speed) of three-phase AC electric motors.This involves calculating an estimate of the motor's magnetic flux and torque based on the measured voltage and current of the motor.
Constant voltage operation above base frequency, and therefore with reduced V/Hz ratio, provides reduced torque and constant power capability. Regenerative AC drives are a type of AC drive which have the capacity to recover the braking energy of a load moving faster than the motor speed (an overhauling load) and return it to the power system.
Vector control, also called field-oriented control (FOC), is a variable-frequency drive (VFD) control method in which the stator currents of a three-phase AC or brushless DC electric motor are identified as two orthogonal components that can be visualized with a vector. One component defines the magnetic flux of the motor, the other the torque ...
Usually the magnetic field is bolted to the machine frame (or uses a torque arm that can handle the torque of the brake). So when the armature is attracted to the field the stopping torque is transferred into the field housing and into the machine frame decelerating the load. This can happen very fast (.1-3sec).
A baby without a father. A mother who carries her son in an urn. Two teens behind bars. Nearly two years after the shooting outside a Whataburger, the families involved are still reeling.
The braking current decays, and after a delay of about 1.5 seconds the braking relay contactor opens again. At this point the motor can be restarted. In such a unit, there are typically two potentiometers, one to vary the braking torque from the firing circuit and the other to vary the timer. These settings are balanced so that braking torque ...
Ad
related to: vfd braking torque definition chart