Xylem IM255 AQUAVAR Intelligent Pump Controller - Manual (Page 84)

NOTE: Be sure to press [OK] then the down arrow to save the No Flow Power Calibration
data. Pressing the down arrow ensures that all background calculations and parameter
settings are performed properly.
NOTE: The No Flow Power Calibration Set-up configures the No Water/Loss of Prime Limit
[22-39]. Do not modify the No Water/Loss of Prime Limit after the No Flow Power
Calibration Set-up is completed. Modification of the No Water/Loss of Prime Limit [22-39]
can cause the No Flow detection and No Water/Loss of Prime detection to malfunction.
In some cases the power calculation based on the calibration data taken during the No
Flow Power Calibration Set-up may require adjustment. The Power Correction Factor
[22-31] parameter allows the calculated power to be adjusted to avoid detection of a no
flow condition while there is flow or to allow detection of a no flow condition while there is
no flow in the system. If a no flow condition is detected while there is flow, the setting
should be decreased. If a no flow condition is not detected while there is no flow, the
setting should be increased above 100%.
No water/loss of prime
The No Water/Loss of Prime function is used to protect the pump against running dry
and/or loss of prime. The function works by monitoring power at full speed and
comparing the actual power to a preset limit. If the actual power falls below this preset
limit for a specified amount of time, the No Water/Loss of Prime alarm is issued. If the No
Water/Loss of Prime function is disabled, the pump will not be protected against running
dry and/or loss of prime.
NOTE: In Duplex Control the No Water/Loss of Prime function is disabled by default on
the lag pump. In Duplex Systems where pumps are fed from different sources the lag
pump should be protected by using the Pump Protect Function. Refer to the Pump
Protect Function for details.
NOTE: In Duplex Systems where pumps are fed from different sources and the lag pump
is able to maintain the system pressure without reaching maximum speed, the No Water/
Loss of Prime condition may not be detected on the lead pump. In this case it is
recommended to delay the starting of the lag pump by setting the Minimum Sleep Time
[22-41] on the lag pump greater than the No Water/Loss of Prime Protection Delay [22-27]
plus the Ramp Up Time [3-41] of the lead pump. Be sure to set this on both controllers
while set to lag if alternation is enabled.
The No Water/Loss of Prime Limit [22-39] is the no flow power value that corresponds to
the speed entered in High Speed [Hz] [22-37]. The No Flow Power Calibration Set-up
automatically enters 85% of the Motor Speed High Limit [Hz] [4-14] in High Speed [Hz]
[22-37].
The No Water/Loss of Prime function works by monitoring the pump power consumption
at full speed, and the No Water/Loss of Prime Limit [22-39] corresponds the pump power
consumption at 85% of full speed. The controller internally scales the No Water/Loss of
Operation
82 Aquavar ® Intelligent Pump Controller INSTRUCTION MANUAL