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3.1.4 Master-Follower Configuration
In this configuration, each pump is controlled by an adjustable frequency drive. All of the pumps and adjustable frequency drives must be of the same
size. Staging and de-staging decisions are made based on the speed of the adjustable frequency drives. Constant pressure is controlled by the master
drive operating in closed-loop. The speed will be the same in all running pumps with extended control. Up to 6 pumps can be controlled (with Advanced
Control, up to 8 pumps).
In master/follower mode, the MCO 101 supports up to 6 pumps - the MCO 102 up to 8 pumps. Please see
Master/Follower Operation Application for FC
200
(Annex A) for further details.
Figure 3.4: 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
→
[2] Drive 3 Enable
27-72 RELAY 10
→
[3] Drive 4 Enable
27-73 RELAY 11
→
[0] Standard Relay
27-74 RELAY 12
→
[0] Standard Relay
The master/follower configuration provides the gentlest transition from one stage to the next and the most energy-efficient operation. For most instal-
lations, the energy savings make this the most cost-effective configuration.
The system will automatically balance all pumps at runtime depending on the pump prioritization set in par. 27-16. The master/follower system provides
a certain level of redundancy. If the master drive trips, it will continue to control the follower drives.
MCB-107 External 24 VDC power supply can be added to increase the level of redundancy.
Furthermore, it reduces wear and tear on pumps and motors. The relays set to [0] Std. Relay, can be used as general purpose relays, controlled by the
parameters in group 5-4*.
3 Supported Configuration
Extended and Advanced Cascade Controller
Option
3-4
MI.38.C2.22 - VLT
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is a registered Danfoss trademark
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