Yaskawa iQpump Manual Supplement - Manual (Page 14)

14 YASKAWA TM.iQp.10 iQpump Technical Manual Supplement
7 Suction Control via Constant Pressure w/Well Draw Down
7 Suction Control via Constant Pressure w/Well Draw Down
‹ Overview
This function enables the iQpump Controller to monitor suction pressure at the inlet of the pumps.
Note: This function is active when parameter P8-01 is set to 2 for Suction Control.
Packaged Booster Systems have a desired discharge pressure and a given suction pressure from the city water system or
from a suction tank. Such systems are often designed to handle a specific pressure and flow rate.
The suction pressure may have a wide range between high and low pressures. The suction pressure typically decreases
with increased fluid flow rate. In some instances, pump cavitation may occur if suction pressure falls below a certain
pressure level.
In addition low or negative suction pressure can lead to damage such as pipe collapse due to external forces acting on the
pipe.
The iQpump Controller will accept an analog suction transducer (Terminal A1) and can be programmed to trigger an
alarm or shutdown the system when the suction pressure falls outside of a normal operating range.The iQpump Controller
will automatically restart and return to normal operation once the suction pressure returns to a normal level.
When operating in multiplex mode, additional control can be programmed to de-stage any active pumps as a method to
try and reduce pump loading to prevent suction pressure from continuing to drop below the shut down level.
„ Function Description
The iQpump Controller will regulate outlet pressure of the pump system using the standard iQpump Controller features
when there is adequate suction pressure available at the inlet of the pumps and offers two options to respond to a drop in
suction pressure.
1. Regulate Outlet Pressure and Suction Pressure: (P8-03 > or = P8-04)
To regulate suction pressure set the suction pressure setpoint (P8-03) to a value greater or equal than the minimum
suction pressure (P8-04). In this mode the iQpump Controller will try to regulate the suction pressure based on the
programmed suction pressure setpoint (P8-03) level.
As the suction pressure decreases and approaches the suction pressure setpoint level (P8-03), the iQpump Controller
will slow down causing the outlet pressure and flow to decrease. When the suction pressure rises above the P8-05 level
for more than the P1-05 time, normal operation (outlet pressure regulation) will resume.
When the suction pressure drops below Minimum Suction Pressure (P8-04), for more than the Sleep Delay Time
(P2-03), the iQpump Controller will go to sleep.
Note: The Suction Control Minimum Speed parameter (P8-06) should be set to a high enough value that will ensure flow.
2. Regulate Outlet Pressure Only: (P8-03 < P8-04)
Set the suction pressure setpoint (P8-03) to a value smaller than the minimum suction pressure (P8-04) to regulate
outlet pressure.
This mode allows the iQpump Controller to maintain the outlet pressure setpoint using the standard iQpump Controller
features and go to sleep immediately when the suction pressure drops below the Minimum Suction Pressure (P8-04),
for more than the Sleep Delay Time (P2-03).
Normal operation (outlet pressure regulation) will resume when the suction pressure returns above the P8-05 level for
more than the P1-05 time.