Lead Pump Alternation Wiring Diagram - Danfoss VLT FC 102 Series Design Manual

Application Examples
7.1.12 Lead Pump Alternation Wiring
Diagram
L1/L2/L3
k3
k2
K1
7 7
Figure 7.10 Lead Pump Alternation Wiring Diagram
Every pump must be connected to two contactors (K1/K2
and K3/K4) with a mechanical interlock. Thermal relays or
other motor protection devices must be applied according
to local regulation and/or individual demands.
•
RELAY 1 (R1) and RELAY 2 (R2) are the built-in
relays in the adjustable frequency drive.
•
When all relays are de-energized, the first built in
relay to be energized cuts in the contactor
corresponding to the pump controlled by the
relay, e.g., RELAY 1 cuts in contactor K1, which
becomes the lead pump.
•
K1 blocks K2 via the mechanical interlock,
preventing line power to be connected to the
output of the adjustable frequency drive (via K1).
•
Auxiliary break contact on K1 prevents K3 from
cutting in.
•
RELAY 2 controls contactor K4 for on/off control
of the fixed-speed pump.
•
At alternation both relays de-energizes and now
RELAY 2 is energized as the first relay.
142
Design Guide
L1/L2/L3
FC
K1
k3 K1
k1
K4
K3
K2 K4
K3
Danfoss A/S © Rev. 06/2014 All rights reserved.
L1/L2/L3
MG11BC22