VYPER
™
VARIABLE SPEED DRIVE
OPERATION
100-210 IOM (
JUL
09)
Page 49
Suggested VFD and Capacity Control Settings
There are individual control strategies required for various
industries. The Vyper
™
VFD and Capacity control settings
provide versatility in meeting these individual needs. The
following pages provide examples of some suggested control
strategies and settings for individual industries. These are
only suggestions. Specific applications may require further
refinements of the control strategy.
NOTE: The operating range of the VSD is between 20% and
100% speed but the advantage of total speed control is
only in effect between the Capacity Control Drive Speed
setting and the Maximum Drive Output setting.
Capacity control can be achieved by adjustment of either the
Slide Valve or the Motor Speed or a combination both. The
full advantages of VSD control is obtained only by fixing the
slide valve and modulating the capacity via Speed control.
The objective is to get the system into total speed control
as quickly as possible and to maintain this strategy in the
expected operating range. This is accomplished by the use of
the proportional control ramp profile during the period that the
slide valve is loading. This allows higher speeds and higher
capacity during the period that slide valve is loading.
Figure 58 provides the VFD and Capacity Control setpoints
typical for operation.
VFD
Maximum Drive Output
100%
Minimum Drive Output
20 %
Delay
Rate of Increase
%
Rate of Decrease
%
Capacity Control
The Drive Speed will increase and decrease proportionally
with the Slide Valve* until the Slide Valve* reaches
98 %
and the Drive Speed reaches
75 %
Above these setpoints, the Drive Speed will be controlled
by the Rate Of Increase and Decrease while the
Slide Valve* will operate independently.
*Slide Valve or other mechanical unloader
Variable Speed Minimum Slide Valve Position
40.0%
Figure 58 - Example 1 VFD and Capacity Control Setpoints
