Wiring Configuration For Lead Pump Alternation - Danfoss VLT HVAC Drive FC 102 Operating Manual

Operating Guide | VLT® HVAC Drive FC 102

7.1.14 Wiring Configuration for Lead Pump Alternation

L1/L2/L3
Drive
K3
K2
K2
K1
Illustration 44: Lead Pump Alternation Wiring Diagram
Every pump must be connected to 2 contactors (K1/K2 and K3/K4) with a mechanical interlock. Apply thermal relays or other motor
overload protection devices according to local regulation and/or individual demands.
• Relay 1 (R1) and relay 2 (R2) are the built-in relays in the drive.
• When all relays are de-energized, the 1
by the relay. For example, relay 1 cuts in contactor K1, which becomes the lead pump.
• K1 blocks for K2 via the mechanical interlock, preventing mains from being connected to the output of the 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-energize and now relay 2 is energized as the 1
For a detailed description of commissioning for mixed pump and master/slave applications, refer to VLT
MCO 101/102 Operating Instructions.
Danfoss A/S © 2020.01
L1/L2/L3
K3
K1
K3
st
built-in relay that is energized cuts in the contactor corresponding to the pump controlled
L1/L2/L3
K1
K1
K4
K3
K4
st
relay.
Wiring Configuration Examples
®
Cascade Controller Options
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