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Variable speed drives allow the
operation of any IBC system to be more user friendly and much
more efficient when compared to systems using manual damper
valves and fixed speed blowers.
The precise control allows operators to make fine adjustments
that are nearly impossible using damper valves. The fine adjustments
can mean the difference between a stable bubble and an unstable
one. However, there are several considerations that should
be investigated before selecting the drive.
Not
all drives are created equal. There is a variety of features
available that may or may not be necessary for the IBC application.
In this case, the general application is a fan. This most
commonly calls for a general purpose, variable torque drive,
with linear ramping, coast to stop, and at least one configurable
dry contact used to report drive faults. Other features, including
interface protocols are also available at extra costs. Review
the headings below for additional information on the most
common VSD concerns. Then review the compatible
drives list and also the drive
checkout procedure below. For drive interface documentation,
please click
here for the DRJ service section (requires registration).
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| Flux
Vector or General Purpose |
Variable
or Constant Torque |
Capacitor
Banks and Braking Resistors |
| Flux
vector drives promise very tight speed control tolerances, but
there is significant effort required to achieve this performance.
For fan applications, the fan has to be separated from the blower
motor and calibrated. This takes considerable time and the value
is difficult to justify. DRJ successfully uses general purpose
drives for all IBC applications. |
Variable
speed drives come in two varieties, constant torque and variable
torque. For all IBC and airing fan applications, variable torque
is sufficient. This is because at low speeds, the fan requires
very little torque to initiate spinning. Generally speaking,
the variable torque drives are less expensive. |
As
drives become available at lower costs and the drive packages
getting smaller, the limited ability to dissipate energy can
cause nuisance trips that shut down the extrusion line. The
specific fault is over voltage on the DC buss. Plan on purchasing
the braking resistor kit for these small package of drives.
Contact us if you have any questions about the drive you are
considering. |
A list of the current
drives that are compatible with the IS-IBC1 system and any special
interface notes.
If the drive is not
on the compatible list, the customer can test the drive against
the functional tests listed in this document.
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