Yaskawa iQpump1000 AC Drive Quick Start - Manual (Page 173)

n Suction Control via Constant Pressure w/Well Draw Down
This function enables the iQpump Controller to monitor suction pressure at the inlet of the pumps.
Note: This function is active when parameter Q5-01 is set to 1 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: Q5-03 ≥ Q5-04
To regulate suction pressure set the suction pressure setpoint (Q5-03) to a value greater or equal than the minimum suction
pressure (Q5-04). In this mode the iQpump Controller will try to regulate the suction pressure based on the programmed
suction pressure setpoint (Q5-03) level.
As the suction pressure decreases and approaches the suction pressure setpoint level (Q5-03), the iQpump Controller will
slow down causing the outlet pressure and flow to decrease. When the suction pressure rises above the Q5-06 level for
longer than the Q5-07 time, normal operation (outlet pressure regulation) will resume.
The iQpump controller goes to sleep when the suction pressure drops below Minimum Suction Pressure (Q5-04), for
longer than the Sleep Delay Time (Q5-05).
Note: The Suction Control Minimum Speed parameter (Q5-08) should be set to a high enough value that will ensure flow.
2. Regulate Outlet Pressure Only: (Q5-03 < Q5-04)
Set the suction pressure setpoint (Q5-03) to a value smaller than the minimum suction pressure (Q5-04) 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 (Q5-04), for
more than the Sleep Delay Time (Q5-05).
Normal operation (outlet pressure regulation) resumes when the suction pressure rises above the Q5-06 level for longer
than the Q5-07 time.
Duplex System Example
Example: A pump system consisting of a duplex domestic pressure booster system using a pressured city supply averaging
40 - 60 psi. When city pressure starts to fall below 40 psi, the pump system will start to slow down to reduce the chances of
pump cavitation. When suction pressure (city pressure) drops to 30 psi, the pump system will shut down (sleep) and wait until
city pressure returns, after which the system will automatically start and operate under normal conditions.
Pump System Settings
• All pumps have the same flow rate and will alternate
• Lag Pump will track speed of lead pump
• All drives have individual discharge transducers rated 150 psi. Upon failure, system will look to network for feedback
information.
• Suction Transducer is rated 75 psi
• Below 40 psi city pressure the pump system will start to reduce speed until reaching 30 psi
• System Auto setpoint 85 psi, with a 5 psi start level.
4.5 iQpump Presets and Functions
YASKAWA TOEP YAIP1W 01B YASKAWA AC Drive - iQpump1000 Quick Start Guide 173
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Start-Up Programming & Operation