Danfoss VLT HVAC Series User Manual

NOTE!
Only valid if par.25-50
Lead Pump Alternation is different from Off [0].
25-56 Staging Mode at Alternation
Option: Function:
This parameter is only active if the option selected in par.25-50 Lead Pump Alternation is different
from
Off [0].
Two types of staging and de-staging of pumps are possible. Slow transfer makes staging and de-
staging smooth. Quick transfer makes staging and de-staging as fast as possible; the variable speed
pump is just cut out (coasted).
[0] * Slow At alternation, the variable speed pump is ramped up to maximum speed and then ramped down
to a stand still.
[1] Quick At alternation, the variable speed pump is ramped up to maximum speed and then coasted to stand
still.
The below figure is an example of the slow transfer staging. The variable speed pump (top graph) and one fixed speed pump (bottom graph) are running
before the staging command. When the
Slow [0] transfer command is activated, an alternation is carried out by ramping the variable speed pump to
par.4-13
Motor Speed High Limit [RPM] or par.4-14 Motor Speed High Limit [Hz] , and then decelerated to zero speed. After a “Delay Before Starting Next
Pump” (par.25-58
Run Next Pump Delay ) the next lead pump (middle graph) is accelerated and another original lead pump (top graph) is added after
the “Delay Before Running On Line Power” (par.25-59
Run-on Line Delay ) as a fixed speed pump. The next lead pump (middle graph) is decelerated to
Motor Speed Low Limit and then allowed to vary speed to maintain system pressure.
25-58 Run Next Pump Delay
Range: Function:
0.1 s* [0.1 - 5.0 s] This parameter is only active if the option selected in par.25-50 Lead Pump Alternation , is different
from
Off [0].
This parameter sets the time between stopping the old variable speed pump and starting another
pump as a new variable speed pump. Refer to par.25-56
Staging Mode at Alternation , the illustration
for description of staging and alternation.
VLT
®
HVAC Drive Programming Guide 3 Parameter Description
MG.11.C6.22 - VLT
®
is a registered Danfoss trademark 3-247
3

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