Instruction manual

Cascade Controller Option
Commissioning the Cascade Controller
To avoid unintended staging during the commissioning
phase and fine tuning of the controller, initially leave the
OBW at the factory setting of 100%. When the fine
tuning is completed, the OBW should be set to the
desired value. A good initial value may be 10%.
Quick Menu 026 Par. 717 Override B andw. timer
(OVER RIDE TIMER)
Value:
0 - 300 sec.
✭ 10 sec.
Function:
Staging a fixed speed pump creates a momentary
pressure peak in the system, which might exceed the
override bandwidth (OBW). It is not desirable to destage
a pump in response to a staging pressure peak.
The override bandwidth timer can be programmed
to prevent staging until the system pressure has
stabilized and normal control established.
Description of choice:
Set the timer to a value that allows the system to
stabilize after staging. The 10 second factory setting
is appropriate in most applications. In highly dynamic
systems, a shorter time might be desirable.
Quick Menu 027 Par. 718 Staging frequency
(STD STAGE FRQ %)
Value:
0 - 100 % of F
max
✭ 90%
Function:
The adjustable speed pump typically runs at maximum
speed when staging on an additional fixed speed
pump to match the system demand.
The instant effect of the fixed speed pump creates
a momentary overpressurization until the adjustable
speed pump decelerates. This is undesirable in
most situations. To avoid this, this drive can be
programmed to decelerate to a staging frequency
before starting the fixed speed pump.
NOTE
Ensure that the staging frequency is set within
the minimum frequency and maximum set
in parameters 201 and 202.
Description of choice:
Adjust the staging frequency to the best compromise
to prevent momentary pressure overshoot and a
pressure drop during transition. A very low value for
the staging frequency might cause the check valve
at the discharge of a variable speed pump to close
during the transition, which could add pressure in the
MG.60.I5.22 - VLT is a registered Danfoss trademark
43
Standard Cascade
Controller Setup