Unequal Size Pump Configuration - Danfoss VLT Series Operating Instructions Manual

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VLT Operating Instructions

1.4.5 Unequal Size Pump Configuration

The Unequal Size Pump configuration supports a limited mix of fixed speed pumps in different sizes. It provides for the largest range of system output
with the smallest number of pumps.
Illustration 1.10: Example
For this configuration relay selections in Group 27-7* "Connections" are as follows:
27-70 RELAY 1 → [73] Pump 2 to Mains
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
Not all configurations of unequal size pumps are valid. For a configuration to be valid it must be possible to stage pumps in increments of 100% of the
size of the Master Drive's variable speed pump. This is necessary since the variable speed pump must be able to control the output between the fixed
speed stages.
Valid Configurations
100% is defined as the maximum flow produced by the pump connected to the Master Drive. The fixed speed pumps must be multiples of this size.
Variable Speed
100%
100%
100%
100%
100%
100% + 100%
100% + 100%
(Other valid configurations are possible)
Invalid Configurations
Invalid configurations will still run but will not stage on all of the pumps. This is done to allow for limited operation if a pump fails or is interlocked in this
configuration.
Fixed Speed
100% + 200%
100% + 200% + 200%
100% + 100% + 300%
100% + 100% + 300% + 300%
100% + 200% + 400%
200%
200% + 200%
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MI.38.C3.02 - VLT is a registered Danfoss trademark
1 Extended and Advanced Cascade Controller
Option
1
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