Xylem 19 001 251 R3 Floboy VFD Pumping System - Manual (Page 18)

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water when the motor is energized. For pump
stations whose inlet is supplied with water under
pressure or from an elevated reservoir, the priming
process is not required other than the removal of
trapped air in the suction pipe. A petcock on the
top of the pump volute should be opened to allow
air to escape and the volute to fill with water. Once
the air has completely escaped, close the petcock.
If the pump station sits above its water source
such that a foot valve is required, the pump will
require priming. Remove the cap from the 3/4"
pipe at the station inlet and fill the suction pipe
using a garden hose or bucket. When the pipe
overflows and water is maintained at the top of the
fill pipe for several minutes, the pipe cap can be
re-installed and tightened. You may have to repeat
this filling process two or more times if air is
trapped anywhere in the suction piping. The
presence of air will cause the pump to instantly
lose pressure once the discharge valve is opened.
PUMP ROTATION
CAUTION
Caution: Always ensure that the pump is
primed prior to checking rotation. Failure to do
so can damage the mechanical seal located in
the motor end of the volute case. These seals
are very sensitive and can be destroyed if
allowed to run dry, even for a very brief period
of time.
It is important to note that the pump is designed to
rotate in a given direction. On most pumps the
proper direction of rotation is noted by an arrow
cast or painted on the exterior of the volute casing.
In the absence of this arrow, one can determine
the proper direction of rotation by observing the
pump from the motor end. Rotation should always
be in a clockwise direction when viewing the pump
from this vantage point. Pump rotation can be
checked by momentarily energizing the motor and
observing the shaft between the motor and the
pump.
Three-phase motors can rotate in either direction.
Checking pump rotation by briefly energizing each
motor is accomplished with a two position switch
labeled "Off/On". The switch is located on the
control panel door and it determines the pump's
mode of operation. The procedure for performing
this check is to first turn the main disconnect on
the outside of the station enclosure to the "On"
position. Next, press the manual button on the
front of the controller, then turn the "Off/On" switch
from "Off" to "On". For the VFD Pump, the motor
speed may need to be increased to approximately
10-20% before the motor will turn. Once motor
rotation has been determined, turn the switch back
to "Off". Reverse rotation of centrifugal pumps is
not damaging but performance and efficiency are
poor and long periods of operation will cause
overheating. Running the pump for a minute or
two to determine rotation will not harm the pump.
PM Pump rotation may be more difficult to
determine. Most PM Pump models motor-pump
coupling is not visible, so a performance check is
required to determine proper rotation. With the
pump primed and the station isolation valve closed
and the controller in “Manual”, turn on the PM
Pump switch (Must be cycled off-then-on if the
switch is on when the change to manual is made).
Note the system pressure. The pump should have
no trouble generating set point pressure in the
discharge manifold. If pressure does not increase
when the pump is started, first verify that the PM
Pump isolation valves are open, that the station
discharge isolation valve is closed, and the
petcock on the discharge pressure gage is open.
If the pump still fails to produce, verify the PM
Pump discharge pressure reducing valve is not
adjusted all the way out. (If set point pressure is to
be higher than the factory setting, this valve may
need to be reset). If the pump still fails to produce,
change rotation of the pump and retest.
WARNING
Caution: Make certain the power is turned off
at the main disconnect switch prior to
changing any electrical leads.
If the rotation is wrong, it can be corrected by
reversing any two leads on the bottom of the
motor starter or VFD (example: move wire A to the
B location and wire B to the A location). Single
phase motors will require internal rewiring which is
best performed by a Flownet technician, and is
normally only required after motor replacement.