Emerson Vission 20/20, Operation And Service Manual

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Vission 20/20 • Operation and Service Manual •Vilter/Emerson • 35391SC 2.0
Section 6 • Compressor Control
Figure 6-4. Compressor Control Screen - VFD Settings Control
Variable Frequency Drive (VFD)
Settings Control
The VFD page is where the operator can tune the motor
VFD for desired operation, see Figure 6-4. Compressor
Control Screen - VFD Settings Control. A Vilter compres-
sor uses the variable speed of a VFD controlled motor to
vary the amount of work or capacity of the compressor.
The basic one step VFD control will use the capacity slide
to control the
fi rst half of the total available capacity and
the motor speed to control the second half of the total
available capacity, see Figure 6-5. VFD One-Step Control
Method. For example, if the compressor needs to load
to 100% of its capacity. The control algorithm will
fi rst
move the capacity slide to its maximum position, and
then the motor speed will ramp up to its maximum
speed. In the unloading direction, the motor speed will
ramp down to its minimum speed, and then the capacity
slide will move to its minimum position.
The two-step control method works much like the
one-step method but divides the control into four sec-
tions, see Figure 6-6. While loading; the compressor will
fi rst move the capacity slide to the maximum set for step
one then speed up the motor to its maximum speed for
the same step. Once step one has completed, the con-
trol algorithm will again move the capacity slide to the
maximum position and the maximum speed of step
two. At this point the compressor would be fully loaded.
Unloading occurs in the reverse direction. The two-step
control method is not typical for most installations and
is normally used when a Vilter engineer recommends it.
NOTE
VFD installation is not covered in this manual. A VFD
that is not properly installed and con
fi gured has the
potential of causing intermittent and dangerous
problems. Please consult your VFD manual.
1 Step VFD Control:
• Enables the
fi rst step in the VFD control algorithm.
This check box is not deselectable by the operator.