Mixed Pump Configuration; Unequal Size Pump Configuration - Danfoss VLT AQUA Operating Instructions Manual

Application Types
In this configuration each pump is controlled by a
frequency converter. All pumps and frequency converters
must be of the same size. Staging and de-staging decisions
are made based on the speed of the frequency converters.
The constant pressure is controlled by the master drive
operating in closed loop. The speed will be the same in all
2 2
running pumps with extended control.
In the Master/Follower mode, MCO 101 supports up to 6
pumps - MCO 102 up to 8 pumps. See 6.1 Master/Follower
for further details.
For the configuration shown Illustration 2.4 relay
selections in parameter group 27-7* Connections are as
follows:
27-70.0 RELAY 1 → [1] Drive 2 Enable
27-70.1 RELAY 2 → [2] Drive 3 Enable
27-70.9 RELAY 10→ [0] Standard Relay
27-70.10 RELAY 11→ [0] Standard Relay
27-70.11 RELAY 12→ [0] Standard Relay
The system will automatically runtime balance all pumps
depending on the pump prioritization made in
27-16 Runtime Balancing. The master/follower system will
provide a certain level of redundancy. If the master drive
trips, it will continue to control the follower drives.
NOTICE
MCB 107 External 24 V DC power supply can be added
to increase the level of redundancy.
Relays set to [0] Std. Relay, can be used as general purpose
relays, controlled by parameter group 5-4* Relays.

2.2.3 Mixed Pump Configuration

This configuration combines 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.
The mixed pump configuration supports a mix of variable
speed pumps connected to frequency converters as well as
additional fixed speed pumps. The variable speed pumps
are staged on and de-staged first based on frequency
converter speed. The fixed speed pumps are then staged
on last and de-staged last based on the feedback pressure.
NOTICE
All variable speed pumps and frequency converters must
be the same size. Fixed speed pumps may be of different
sizes.
8
®
VLT AQUA Drive MCO 101/MCO 102
Illustration 2.5 Example
For this configuration relay selections in parameter
group 27-7* Connections are as follows:

2.2.3.1 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 2.6 Example
For this configuration relay selections in parameter
group 27-7* Connections are as follows:
®
MI38C402 - VLT is a registered Danfoss trademark
27-70.0 RELAY 1 → [1] Drive 2 Enable
27-70.1 RELAY 2 → [74] Pump 3 to Mains
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
100% 100%
27-70.0 RELAY 1 → [73] Pump 2 to Mains
27-70.1 RELAY 2 → [74] Pump 3 to Mains
200% 200%