18-06-2013, 03:06 PM
AC drives
[attachment=55642]
intro
AC drives are used to bring about process and quality improvements in industrial and commercial applications' acceleration,
flow, monitoring, pressure, speed, temperature, tension and torque.
AC drives can also run a motor in specialized patterns to further minimize mechanical and electrical stress. For
example, an S-curve pattern can be applied to a conveyor application for smoother deceleration and acceleration control,
which reduces the backlash that can occur when a conveyor is accelerating or decelerating.
Many fixed-speed motor load applications that are supplied direct from AC line power can save energy when they are operated
at variable-speed, by means of VFD. Such energy cost savings are especially pronounced in variable-torque centrifugal fan and
pump applications, where the loads' torque and power vary with the square and cube, respectively, of the speed. This change
gives a large power reduction compared to fixed-speed operation for a relatively small reduction in speed. For example, at 63%
speed a motor load consumes only 25% of its full speed power. This is in accordance with affinity laws that define the relationship
between various centrifugal load variables.
[attachment=55642]
intro
AC drives are used to bring about process and quality improvements in industrial and commercial applications' acceleration,
flow, monitoring, pressure, speed, temperature, tension and torque.
AC drives can also run a motor in specialized patterns to further minimize mechanical and electrical stress. For
example, an S-curve pattern can be applied to a conveyor application for smoother deceleration and acceleration control,
which reduces the backlash that can occur when a conveyor is accelerating or decelerating.
Many fixed-speed motor load applications that are supplied direct from AC line power can save energy when they are operated
at variable-speed, by means of VFD. Such energy cost savings are especially pronounced in variable-torque centrifugal fan and
pump applications, where the loads' torque and power vary with the square and cube, respectively, of the speed. This change
gives a large power reduction compared to fixed-speed operation for a relatively small reduction in speed. For example, at 63%
speed a motor load consumes only 25% of its full speed power. This is in accordance with affinity laws that define the relationship
between various centrifugal load variables.