Danfoss VLT Series Design Manual page 133

VLT ® HVAC Drive Design Guide
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6.1.13. Cascade Controller Wiring Diagram
The wiring diagram shows an example with the built in BASIC cascade controller with one variable
speed pump (lead) and two fixed speed pumps, a 4-20 mA transmitter and system safety interlock.
6.1.14. Start/Stop conditions
Commands assigned to digital inputs. See
Start (SYSTEM START /STOP) Ramps up (if stopped and
Lead Pump Start
Coast (EMERGENCY STOP)
Safety Interlock
Function of buttons on the Local Control Panel
Hand On
OFF
Auto On
RELAY 2 controls contactor K4 for on/off control of the fixed speed pump.
At alternation, both relays de-energize, and RELAY 2 will be energized as the first relay.
Variable speed pump (lead)
there is a demand)
Ramps up if SYSTEM START is
active
Coast to stop
Coast to stop
Variable speed pump (lead)
Ramps up (if stopped by a nor-
mal stop command) or stays in
operation if already running.
Ramps down
Starts and stops according to
commands via terminals or se-
rial bus.
MG.11.B4.22 - VLT ® is a registered Danfoss trademark.
Digital Inputs , par.5-1*.
Fixed speed pumps
Staging (if stopped and there
is a demand)
Not affected
Cut out (built in relays are de-
energized)
Cut out (built in relays are de-
energized)
Fixed speed pumps
De-staging (if running)
Ramps down
Staging/De-staging
6. Application Examples
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