16
Manual VFD Operation
Overview
Manual operation is selected by the system
control switch. In manual operation, all pump
activity is controlled by the individual pump
switches. In the case of multiple pumps
available for VFD operation, the VFD select
switch determines which pump(s) run in VFD
mode. However, some stations do not come
equipped with a VFD select switch. In that
case, the first pump that is started is always
the VFD pump. The speed of the VFD pump is
controlled by the speed potentiometer (speed
pot). All other pumps run in XL mode (at full
speed). The Override/Active switch enables or
disables the low-discharge pressure fault.
NOTE:
Manual operation is rarely used.
However, it does allow for operation of
individual pumps for testing purposes.
Sequence of Operation (performed in
order)
System control switch: OFF
All Individual Pump switches: OFF
Override/Active switch: LDP Override
(Low Discharge Pressure fault disabled). If
initial system pressure is high enough,
place in Active.
VFD Bypass switch: VFD
VFD Select switch: Pump 1
Speed
Potentiometer:
Turned
100%
counter-clockwise (0 speed)
System control switch: MANUAL
Pump 1 switch: ON
Speed Potentiometer: Turn clockwise to
increase speed of pump 1
Pump 2 switch: ON (if required)
Speed Potentiometer: Adjust speed as
required to maintain set point pressure.
Pump 3 switch: ON (if required)
Speed Potentiometer: Adjust speed as
required to maintain set point pressure.
NOTE:
When done, turn OFF all pump
switches and place system control switch in
OFF.
Return
Override/Active
switch
to
ACTIVE. If the station can be run in Automatic
mode, return the system switch to AUTO and
turn ON all pump switches.
VFD Bypass Operation, Manual mode
Overview
This is an abnormal operating mode and
would only be used when the VFD (inverter) is
not operable but there is a need to irrigate. If
the PLC is operable, and PRV (Pressure
Reducing Valve) is in the system and
functioning, we strongly recommend using
Automatic VFD Bypass Mode.
WARNING: Manual VFD Bypass Hazard
This mode of operation should be used as a last
resort if there is no DSR, or it is not functioning
correctly.
Constant
operator
attendance
is
recommended when this mode is used. The water
demand must be calculated to match the
individual pump output as closely as possible.
Failure to do so will cause a serious over-pressure
condition.
Failure to follow these instructions could result in
serious personal injury, death, or property
damage.
System Operation (performed in order)
System control switch: OFF
All Individual Pump switches: OFF
Override/Active switch: LDP Override
(Low Discharge Pressure fault disabled). If
initial system pressure is high enough,
place in ACTIVE.
VFD Bypass switch: BYPASS
VFD Select switch: Pump 1
Speed Potentiometer: N/A
System control switch: MANUAL
Pump 1 switch: ON
Allow system pressure to stabilize before
turning on additional pumps.
Pump 2 switch: ON (if required)
Pump 3 switch: ON (if required)
