Master-Follower Configuration - Danfoss VLT Series Operating Instructions Manual

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VLT Operating Instructions

1.4.3 Master-Follower Configuration

In this configuration each pump is controlled by a frequency converter. All of the 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 running pumps with extended control. Up to 6 pumps can be controlled (with Advanced Control up to 8
pumps).
In the Master/Follower mode, MCO 101 supports up to 6 pumps - MCO 102 up to 8 pumps. Please see
200
(Annex A) for further details.
Illustration 1.8: 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 installations
the energy savings make this the most cost effective configuration.
The system will automatically runtime balance all pumps depending on the pump prioritization made in par. 27-16. The Master/Follower system will
provide 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*.
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MI.38.C3.02 - VLT is a registered Danfoss trademark
1 Extended and Advanced Cascade Controller
Master/Follower Operation Application for FC
Option
1
13