Mixed Pump Configuration With Alternation - Danfoss VLT AQUA Operating Instructions Manual

Application Types
27-70.9 RELAY 10 → [75] Pump 4 to Mains
27-70.10 RELAY 11→ [0] Standard Relay
27-70.11 RELAY 12→ [0] Standard Relay
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. The variable speed
pump must control the output between the fixed speed
stages, see Illustration 2.7.
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.
NOTICE
Other valid configurations than the ones shown in
Table 2.2 are possible
Variable Speed Fixed Speed
100% 100% + 200% (see Illustration 2.7)
100% 100% + 200% + 200%
100% 100% + 100% + 300%
100% 100% + 100% + 300% + 300%
100% 100% + 200% + 400%
100% + 100% 200%
100% + 100% 200% + 200%
Table 2.2 Valid Configurations
C
400 %
300 %
200 %
100 %
100 %
100 % 100 % 200 %
1 2
Illustration 2.7 Valid Configuration Example
NOTICE
Invalid configurations, like in Illustration 2.8, will still run
but will not stage on all pumps. This feature allows for
limited operation if a pump fails or is interlocked.
®
VLT AQUA Drive MCO 101/MCO 102
100 %
100 %
100 %
200 %
3 4
®
MI38C402 - VLT is a registered Danfoss trademark
Variable Fixed Speed
Speed
100% 200%
100% 100% + 300%
100% 100% + 200% +
600%
Table 2.3 Invalid Configurations
C
400%
300%
200%
100%
100%
300 %
100%
100%
1 2
Illustration 2.8 Invalid Configuration Example
2.2.3.2 Mixed Pump Configuration with
Alternation
In this configuration the frequency converter alternates
between two pumps and controls the other as additional
fixed speed pump. The Cascade Controller attempts to
balance the running hours of the pumps.
(no control between 100%
and 200%)
(no control between 200%
and 300%) (see Illustration 2.8)
(no control between 400%
and 600%)
100%
100%
100%
300 %
3 4
9
2 2