Pump Staging With Lead Pump Alternation; System Status And Operation; Fixed Variable-Speed Pump Wiring Diagram - Danfoss VLT FC 102 Series Design Manual

Application Examples
7.1.9 Pump Staging with Lead Pump
Alternation
Figure 7.8 Pump Staging with Lead Pump Alternation
With lead pump alternation enabled, a maximum of two
pumps are controlled. At an alternation command, the
lead pump ramps to minimum frequency (f
delay will ramp to maximum frequency (f
speed of the lead pump reaches the destaging frequency,
the fixed-speed pump is cut out (destaged). The lead
pump continues to ramp up and then ramps down to a
stop and the two relays are cut out.
After a time delay, the relay for the fixed-speed pump cuts
in (staged) and this pump becomes the new lead pump.
The new lead pump ramps up to maximum speed and
then down to minimum speed. When ramping down and
reaching the staging frequency, the old lead pump is now
cut in (staged) on the line power as the new fixed-speed
pump.
If the lead pump has been running at minimum frequency
(f ) for a programmed amount of time, with a fixed-
min
speed pump running, the lead pump contributes little to
the system. When the programmed value of the timer
expires, the lead pump is removed, avoiding a heat water-
circulation problem.
MG11BC22
Design Guide

7.1.10 System Status and Operation

If the lead pump goes into Sleep Mode, the function is
displayed on the LCP. It is possible to alternate the lead
pump on a sleep mode condition.
When the Cascade Controller is enabled, the operation
status for each pump and the Cascade Controller is
displayed on the LCP. Information displayed includes:
•
•
) and after a
min
). When the
max
•
7.1.11 Fixed Variable-speed Pump Wiring
Figure 7.9 Fixed Variable-speed Pump Wiring Diagram
Danfoss A/S © Rev. 06/2014 All rights reserved.
Pumps Status, is a readout of the status for the
relays assigned to each pump. The display shows
pumps that are disabled, off, running on the
adjustable frequency drive, or running on the line
power/motor starter.
Cascade Status, is a readout of the status for the
Cascade Controller. The display shows the
cascade controller is disabled, all pumps are off,
and emergency has stopped all pumps, all pumps
are running, fixed-speed pumps are being
staged/de-staged and lead pump alternation is
occurring.
Destage at No-Flow ensures that all fixed-speed
pumps are stopped individually until the no-flow
status disappears.
Diagram
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