Danfoss VLT HVAC Series User Manual

3.23.5 25-5* Alternation Settings
Parameters for defining the conditions for alternation of the variable speed pump (lead), if selected as part of the control strategy.
25-50 Lead Pump Alternation
Option: Function:
Lead pump alternation equalizes the use of pumps by periodically changing the pump that is speed
controlled. This ensures that pumps are equally used over time. Alternation equalizes the usage of
pumps by always choosing the pump with the lowest number of used hours to stage on next.
[0] * OFF No alternation of lead pump function will take place. It is not possible to set this parameter to options
other that
Off [0] if par.25-02 Motor Start is set other than Direct on Line [0].
[1] At staging Alternation of the lead pump function will take place when staging another pump.
[2] At command Alternation of the lead pump function will take place at an external command signal or a pre-pro-
grammed event. See par.25-51
Alternation Event for available options.
[3] At staging or at command Alternation of the variable speed (lead) pump will take place at staging or the “At Command” signal.
(See above.)
NOTE!
It is not possible to select other than
Off [0] if par.25-05 Fixed Lead Pump is set to Yes [1].
VLT
®
HVAC Drive Programming Guide 3 Parameter Description
MG.11.C6.22 - VLT
®
is a registered Danfoss trademark 3-245
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Danfoss VLT HVAC Series Specifications

General

Protection Features	Overcurrent, Overvoltage, Undervoltage, Overtemperature, Short circuit
Communication Interfaces	Profibus, Ethernet
Cooling Method	Forced convection
Ambient Temperature	-10°C to +40°C
Enclosure Rating	IP20, IP21, IP55
Output Voltage	0 - 100% of supply voltage