When a variable frequency drive decelerates an AC motor, especially one with a large inertial load attached, a braking resistor may be required to help dissipate the energy. Larger AC drives also require that dynamic braking units be used in conjunction with the appropriate braking resistors.
Input line reactors protect the AC drive from transient overvoltage conditions typically caused by utility capacitor switching. Input line reactors also reduce the harmonics associated with AC drives and are recommended for all installations.
Output line (load) reactors protect the motor insulation against AC drive short circuits and IGBT reflective wave damage, and also allow the motor to run cooler by "smoothing" the motor current waveform. They are recommended for operating "non-inverter-duty" motors, and for any motors where the length of wiring between the AC drive and motor is less than 100 feet.
For AC Drive-to-Motor wiring distances over 100 feet, use of the VTF series output filter is recommended.
Braking resistors are used to increase the braking torque of the AC drive, for frequently repeated ON-OFF cycles of the AC drive, or for decelerating a load with large inertia.
Larger AC drives also require that dynamic braking units be used in conjunction with the appropriate braking resistors.
Drive configuration and programming software allows the user to connect to a VFD from a PC for fast, convenient setup and/or programming of a built-in PLC, and offline storage of (multiple) configuration parameters.
Option cards are available to increase the available I/O or add communications capabilities.
Replacement cooling fans for drives are direct replacements, dimensionally and electrically equivalent to the original part. Fan electrical loading is included in the input amperage ratings of the drives, and the DC voltage to power the fans is provided internally by the drives.
An assortment of accessories to complete your VFD installation includes:
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