Johnson Controls VFD66 Series, Product/Technical Bulletin

Page: 9 / 17

Selecting an Input Mode
See Table 6 for the available input mode options for
the VFD66 control. The factory–set mode is Manual
Input mode.
Manual Input Mode
Manual Input mode allows the user to set a constant
motor speed. This can be used where manual control
is desired or while repairing input signal devices or
obtaining replacements. In Manual Input mode, the input
device signals are disregarded. Motor speed is controlled
by adjusting the P1 potentiometer. Potentiometer P2 is
disregarded and adjusting P2 has no effect.
Table 7: Manual Input Mode
J2 Jumper
Position J3 Jumper
Position P1:
Motor Speed P2:
Not
Used
Installed Installed Adjusts constant
speed of motor
(0-100%)
—
Standard Input Mode
Standard Input mode is the most commonly used
mode. The majority of input devices compatible with
the VFD66 controls are used with this mode. The input
device determines the setpoint and proportional band.
Table 8: Standard Input Mode
J2
Jumper
Position J3
Jumper
Position P1:
Minimum
Motor
Speed P2: Motor
Action at
Minimum
Speed
CCW:
Motor idles. Installed Removed Can be set at
0-50% of
maximum
motor speed.
CW: Motor
shuts off.
P1 adjusts the minimum speed of the motor. The
minimum speed is adjustable from 0 to 50% of total
motor speed. Turning P1 Clockwise (CW) increases
minimum speed setting, Counterclockwise (CCW)
decreases minimum speed setting.
P2 determines whether the motor idles at minimum
speed or shuts off at minimum speed. P2 must be set
at full CCW or full CW position; intermediate settings
have no effect.
Figure 12 illustrates three possible motor speed
curves. When P2 is rotated fully CCW, the motor idles
at the minimum speed set by P1 at input values below
the end of the proportional band (Curve A in
Figure 12). When P2 is rotated fully CW, the motor
shuts off at the minimum speed set by P1 when the
input is below the bottom end of the proportional band
(Curve B in Figure 12).
In Curve C, the minimum motor speed (P1) is set at
0% of maximum motor speed and the position of
P2 has no effect.
Pressure or Temperature
RPM
100%
50%
Setpoint
Proportional Band
40%
30%
Minimum
Motor Speed
Set by P1
Idle
Curve B
P2=CW
P1=30%
Curve C
P2=CCW or CW
P1=0%
Curve A
P2=CCW
P1=40%
0%
Figure 12: Standard Input Mode
VFD66 Series Condenser Fan Speed Controls Product/Technical Bulletin 9