Mixed Pump Configuration - Danfoss VLT Series Operating Instructions Manual

1 Extended and Advanced Cascade Controller
Option

1.4.4 Mixed Pump Configuration

1
The Mixed Pump configuration supports a mix of variable speed pumps connected to Drives as well as additional fixed speed pumps. In this configuration
all of the variable speed pumps and Drives must be the same size. The fixed speed pumps may be of different sizes. The variable speed pumps are staged
on and staged off first based on Drive speed. The fixed speed pumps are then staged on last and staged off last based on the feedback pressure.
Illustration 1.9: Example
For this configuration relay selections in Group 27-7* "Connections" are as follows:
27-70 RELAY 1 → [1] Drive 2 Enable
27-71 RELAY 2 → [74] Pump 3 to Mains
27-72 RELAY 10→ [75] Pump 4 to Mains
27-73 RELAY 11→ [0] Standard Relay
27-74 RELAY 12→ [0] Standard Relay
This configuration provides some of the benefits of the Master Follower configuration with some of the initial cost savings of the Fixed Speed configuration.
It is a good choice when the extra capacity of the fixed pumps is rarely needed.
14
®
MI.38.C3.02 - VLT is a registered Danfoss trademark
®
VLT Operating Instructions