Danfoss VLT HVAC Series, Programming Manual, Page: 261 / 338

25-04 Pump Cycling
Option: Function:
To provide equal hours of operation with fixed speed pumps, the pump use can be cycled. The
selection of pump cycling is either “first in – last out” or equal running hours for each pump.
[0] * Disabled The fixed speed pumps will be connected in the order 1 – 2 and disconnected in the order 2 – 1.
(First in – last out).
[1] Enabled The fixed speed pumps will be connected/disconnected to have equal running hours for each pump.
25-05 Fixed Lead Pump
Option: Function:
Fixed Lead Pump means that the variable speed pump is connected directly to the adjustable fre-
quency drive, and if a contactor is applied between adjustable frequency drive and pump, this
contactor will not be controlled by the adjustable frequency drive.
If operating with par.25-50
Lead Pump Alternation set to other than Off [0], this parameter must be
set to No [0].
[0] No The lead pump function can alternate between the pumps controlled by the two built in relays. One
pump must be connected to the built-in RELAY 1, and the other pump to RELAY 2. The pump
function (Cascade Pump1 and Cascade Pump2) will automatically be assigned to the relays (maxi-
mum two pumps can in this case be controlled from the adjustable frequency drive).
[1] * Yes The lead pump will be fixed (no alternation) and connected directly to the adjustable frequency
drive. The par.25-50
Lead Pump Alternation is automatically set to Off [0]. Built-in relays Relay 1
and Relay 2 can be assigned to separate fixed speed pumps. A total of three pumps can be controlled
by the adjustable frequency drive.
25-06 Number Of Pumps
Range: Function:
2 N/A* [2 - 9. N/A] The number of pumps connected to the cascade controller including the variable speed pump. If
the variable speed pump is connected directly to the adjustable frequency drive and the other fixed
speed pumps (lag pumps) are controlled by the two built-in relays, three pumps can be controlled.
If both the variable speed and fixed speed pumps are to be controlled by built-in relays, only two
pumps can be connected.
If
par.25-05 Fixed Lead Pump, Fixed Lead Pump
, is set to
No
[0]: one variable speed pump and one
fixed speed pump; both controlled by a built-in relay. If
par.25-05 Fixed Lead Pump, Fixed Lead
Pump
, is set to
Yes
[1]: one variable speed pump and one fixed speed pump controlled by a built-
in relay.
One lead pump, see par.25-05 Fixed Lead Pump . Two fixed speed pumps controlled by built-in
relays.
VLT ® HVAC Drive Programming Guide 3 Parameter Description
MG.11.C6.22 - VLT ® is a registered Danfoss trademark
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