Rockwell Automation 1336VT 5-300 AMP (2.2-160KW) - Manual (Page 26)

Overview
Chapter 3
3-10
The 1336VT is an AC adjustable frequency drive designed for use with a
standard, three-phase induction motor. The standard control is designed as
a constant torque, adjustable speed control with 115% overload capability
and is adaptable through programming to handle a wide variety of
applications.
The 1336VT provides an exceptional output voltage and current waveform.
Special considerations however, must be taken when applying an inverter
to an existing motor.
The 1336VT provides a three-phase motor with variable frequency and
voltage utilizing PWM (Pulse Width Modulated) technology. Varying the
frequency of the applied power to the motor varies the speed of the motor.
The 1336VT is designed for use with variable torque, square law and
cubed law loads. With square law loads, the torque varies directly with the
change in speed while the horsepower varies as the square of the speed
change. With cubed law loads, the torque varies as the square of the speed
change while the horsepower varies as the cube of the speed change.
Typical examples of square law loads are:
•
Some positive displacement pumps.
•
Some extruders and some mixers.
Typical examples of cube law loads are:
•
Some centrifugal pumps.
•
Fans and blowers.
Regardless of whether your application is a square law or cube law load,
sizing of the 1336VT should be based upon the motor load current required
at maximum operating speed. Caution is advised in going above motor
base (nameplate) speed in these applications.