Franklin Electric CERUS X-DRIVE CXD-003A-4V, Installation And Operation Manual

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ADVANCED APPLICATION OPTIONS
Multi-Drive Configurations
108
VFD Role Definitions for Multi-Drive Operation
NOTE: For proper system operation each VFD should have active run command and HOA switch in Auto
mode and all VFDs should have identical control parameter settings.
Master: The drive that controls starting of the overall system and activating each pump.
• The Master is always the VFD with the lowest ID. In addition, the
Set VFD Ready [ADV–47]
parameter must
be set to 0_Ready .
• If the Master loses communication to the system, the remaining VFD with the lowest ID takes over as
Master. For this reason, the best practice is to program all drives with the same parameter settings.
• The overall system becomes active when the Master is in Auto.
• The Master monitors its own transducer, along with the Lead drive frequency to determine when to
start or stop remaining drives.
• The Master can also function in any of the other roles.
• If the Master HOA is put in OFF position, the whole system will stop.
Lead:
The Lead VFD operates in PID mode using its transducer as feedback to control the speed.
• If the drive is set to operate at a fixed frequency, it cannot function as a Lead.
• Assignment of the Lead drive can be assigned to other drives on a rotating basis.
IMPORTANT: Since the Lead role can change, each drive needs its own transducer; or, the system could
have a single transducer with analog splitters to feed each drive. Each drive needs to be set to the same
setpoint. If a change in setpoint is needed, the setting needs to be updated on all the drives.
Lag:
A Lag drive becomes active when the Master determines that the setpoint cannot be met by the Lead.
•
VLag Spd Source [ADV–43]
sets the Lag drive to run either on its own PID or at a fixed frequency. For a Lag
drive to be alternated to a Lead, it must be set to PID mode.
NOTE:
If a Lag is operating in PID mode, it could possibly run at a higher frequency than the Lead at
times as the overall system balances itself.
Standby:
A Standby drive is not part of the Lead/Lag control sequence, but it can be a Master. One or more
Standby drives serve as spares to replace a Lead or Lag in a faulty or deactivated condition, and are added
at the end of the sequence of drives.
VFD-1
Master/
Follower
VFD-2
Follower/
Master
VFD-3
Follower/
Master
VFD-4
Follower/
Master
Lead
Pump
Lag1
Pump
PT1-PT4 are Pressure Transducers
X-Drive
Com
Cable
X-Drives Multi-VFD pump system with full Master/Follower Control
X-Drive X-Drive
X-Drive
Com
Cable
Com
Cable
PT1 PT2 PT3 PT4
Lag2
Pump
Standby1
Pump