Service manual

6 – 4

Vission 20/20 • Operation and Service Manual •Vilter/Emerson • 35391SC 1.9

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, 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, 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 sections,

see Figure 6-6. VFD Two-Step Control Method. 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 control algorithm will again

move the capacity slide to the maximum position and

the maximum speed of step two. At this point the com-

pressor 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 conﬁ 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.

Capacity Slide Position:

Section 6 • Compressor Control

Figure 6-4. Compressor Control Screen - VFD Settings Control