Running the Pump
20
311596A
Flow Control
Motor Speed Control
Motor speed is set indirectly, by setting Pump Flow
Rate, which is then translated to motor speed by Graco
Software.
Motor Speed is set via Preset Reference 1. Refer to
Unidrive SP User Guide, Menu 1: Frequency / Speed
Reference Logic Diagram.
Local Mode – Keypad Flow Control
Resistance of 0 ohms corresponded to zero flow.
Increase in resistance equals increase in flow. Use Pr
5.01 to monitor instantaneous speed of the motor (in
Hz).
Hardware required – 5 k ohm Variable Resistor (Potenti-
ometer). Refer to Control Technique Unidrive SP User
Guide for more details on electrical installation (also see
System Electrical Diagrams, page 36).
If Speed Potentiometer is not installed, flow can be con-
trolled directly from the Keypad. The following conditions
must be true:
1.
Speed Potentiometer Enable = Disable (Pr 20.38 =
0).
2.
Control Mode = Local (Local/Remote switch in Local
position; Digital I/O #5 (Pin #28) is grounded (Com-
mon ground is available at VFD pins #1, 3, 11, 21,
23, and 30).
Enter desired flow into Pr 20.05 as follows:
1.
Determine desired flow (for example, 12 gallons per
minute [gpm]).
2.
Multiply desired flow by 10 (12gpm*10 = 120gpm).
3.
Enter the result into parameter Pr 20.05 (enter num-
ber 120).
Speed Potentiometer control mode is available if the fol-
lowing conditions are valid:
1.
Speed Potentiometer Enable = (Pr 20.38 = 1).
2.
Control Mode = Local (Local/Remote switch in Local
position; Digital I/O #5 (Pin #28) is grounded (Com-
mon ground is available at VFD pins #1, 3, 11, 21,
23, and 30).
Remote Mode
To have a remote control, the following condition must
be true:
Control Mode = Remote (Local/Remote switch in
Remote position; Digital I/O #5 (Pin #28) is floating.
Flow is controlled by the Pr 20.05. Keypad or Modbus
communication protocol can be used to alter value of Pr
20.05.
Multiply desired flow value by 10 (see Local Mode –
Keypad Flow Control above for more details).
F
IG
. 5
VFD
Internal 10 VDC
Common Ground
RUN/STOP
4
5
6
1
Differential Analog Input (-)
Differential Analog Input (+)
SPEED POT
(5 k ohm)
The speed potentiometer mode has no effect even
while enabled.
