3.24 Parameters 27-** Cascade CTL Option
Parameter group 27-** Cascade CTL Option
is available if 1
of the following conditions is met:
•
VLT
®
Extended Cascade Controller MCO 101 is
installed.
•
VLT
®
Advanced Cascade Controller MCO 102 is
installed.
•
The frequency converter was ordered with the
type code LXX1.
Relay wiring configuration using MCO 101 or MCO 102
For a detailed description of commissioning for mixed
pump and master/slave applications (using relay
operation), refer to
VLT
®
Cascade Controller Options MCO
101/102 Operating Instructions
.
Serial communication wiring configuration
The serial communication wiring configuration supports
the master/slave cascade controller set-up controlling up to
8 pumps in total.
At least 1 of the frequency converters in the set-up must
have
parameter group 27-** Cascade CTL Option
enabled.
That enables option
Modbus CASCADE Master
in
parameter 8-30 Protocol
.
The frequency converter with the lowest address and the
cascade controller capability is set as the primary master.
The remaining frequency converters must be addressed
with a unique address or forward-running number.
For slave frequency converters, option
Modbus RTU
in
parameter 8-30 Protocol
has to be set. Reaction at
communication loss can be set in
and
parameter 8-04 Control Timeout Function
Apply this setting to all frequency converters in the
system.
This configuration only supports the master/slave mode.
NOTICE
Terminate the RS485 bus with a resistor at both ends.
For this purpose, set switch S801 on the control card to
ON.
68
69
1
2
3
4
68
69
68
69
68
69
e30bg296.10
1 Primary master 1
2 Slave 1
3 Slave 2
4 Slave X (up to 7 slaves)
Illustration 3.95 Serial Communication Wiring
3.24.1 Master/Slave Configuration
The master/slave cascade control mode offers the best
performance, the most precise control, and maximum
energy savings. This mode controls multiple equally sized
pumps in parallel, running all pumps at the same speed
and stages the pumps on and off according to system
requirements.
Compared to the closed-loop cascade control, staging and
destaging decisions are made based on the speed
calculated by frequency converters instead of feedback.
Set the stage-on and stage-off speed according to the
system requirements to obtain the highest energy saving.
In the master/slave configuration, the master frequency
converter is running in closed loop, and the slave
frequency converters are running in open loop. All slave
frequency converters are connected to mains and the
motors in the same way as the master frequency converter.
In this configuration, each pump is controlled by a
frequency converter. All pumps and frequency converters
must be of the same size.
3.24.2 Mixed Pump Configuration
This configuration combines some of the benefits of the
master/slave configuration with some of the initial cost
savings of the fixed speed configuration. Use this configu-
ration when the extra capacity of the fixed pumps is rarely
needed.
The mixed pump configuration supports a mix of variable
speed pumps connected to the frequency converters with
extra fixed speed pumps. The variable speed pumps are
staged on and destaged first based on the frequency
converter speed. The fixed speed pumps are then staged
on last and destaged last based on the feedback pressure.
Parameter Description
Programming Guide
MG20OB02
Danfoss A/S © 05/2018 All rights reserved.
223
3
3
Summary of Contents for VLT AQUA Drive FC 202
Page 2: ......
