Xylem IM255 AQUAVAR Intelligent Pump Controller - Manual (Page 71)

Duplex control
The Duplex Control Mode configures the controller for operation in a system with 2
controllers and 2 variable speed pumps. Each controller is connected to a single pump.
When configured as a lead/lag system (Duty Standby Disabled) the pumps can be staged
or destaged as the demand requires. When both pumps run at the same time they will
operate at the same speed. The lead controller/pump can be switched/alternated
between the 2 controllers.
NOTE: The Duplex Control Mode requires specific control wiring for proper operation.
Consult the Wiring to Control Terminals section in this manual for details.
NOTE: The Duplex Control Mode requires specific parameter settings to proper
operation. Changing to Duplex Control will overwrite any preconfigured parameters.
As in the previously described application types, the control units and ramp times are
configured first. The next screen allows the user to automatically configure the rest of the
parameters to default settings. The only parameter that must be set after selecting Yes is
the setpoint. After the setpoint is configured the setup of the controller is complete. The
default configurations are described in the table below.
Table 20: Duplex Autoset Configuration
Duplex Autoset Configuration
Transducer Max. Feedback 300 [unit]
Transducer Type 4–20mA
Feedback 1 Source AI 53
Sleep Frequency 30 Hz
Restart Difference 5 [unit]
No Water/Loss of Prime Fault Enabled
Duty Standby Disabled
Lag Start Freq 59 Hz
Lag Stop Freq 35 Hz
Alternation Enabled
Alternate Time 24 Hrs
Pump Exercise Time 0 s (Disabled)
Duty standby
Enabling Duty Standby allows the system to be configured as a 2 pump redundant
system. With Duty Standby enabled both pumps will not run at the same time during
normal operation. Only the lead pump will run when required.
The pumps can be configured to alternate the lead pump by enabling Alternation.
Disabling Duty Standby configures the 2 pump system as a lead/lag system. With Duty
Standby disabled, the pumps can be staged/destaged as required based on system
demand.
NOTE: If Duty Standby is enabled, both pumps may run at the same time during
alternation, after a start command is received or after an alarm is reset depending on the
setting of Start Delay [1-71]. Set the Start Delay [1-71] longer than the Ramp Down Time
[3-42] of the other pump or 3 seconds, whichever is longer, to avoid this condition. Refer
Operation
Aquavar ® Intelligent Pump Controller INSTRUCTION MANUAL 69