Two 4 - 20 Ma Feedback Transmitters Connection; Two Feedback Signals And Two Setpoints; Programming Example - Danfoss Cascade Operating Instructions Manual

Programming:
Parameter Parameter
Number Description
415 Ref./FDBK UNIT
413 MIN. FEEDBACK
414 MAX. FEEDBACK
417 2 FEEDBACK CALC.
308 AI [V] 53 FUNCT.
309 AI 53 SCALE LOW
310 AI 53 SCALE HIGH
311 AI [V] 54 FUNCT.
312 AI 54 SCALE LOW
313 AI 54 SCALE HIGH
314 AI [mA] 60 FUNCT.

Two 4 - 20 mA feedback transmitters connection:

When two feedback signals are used, the VLT requires
that they both be connected to its analog voltage
inputs, terminals 53 and 54. Transmitters that produce
a current signal can be used by adding two resistors.
If the transmitter is capable of producing 10V at 20
mA, the value of the resistor to use is:
The input scaling of the VLT analog inputs in this
case would have to be 2 - 10 Volt.
Programming:
Parameter Parameter
Number Description
415 Ref./FDBK UNIT
413 MIN. FEEDBACK
414 MAX. FEEDBACK
417 FEEDBACK CALC.
308 AI [V] 53 FUNCT.
309 AI 53 SCALE LOW
310 AI 53 SCALE HIGH
311 AI [54] 54 FUNCT.
312 AI 54 SCALE LOW
313 AI 54 SCALE HIGH
314 AI [mA] 60 FUNCT.
MG.60.I3.02 - VLT is a registered Danfoss trademark
Parameter
Value
Process unit
Transmitter low limit
Transmitter high limit
Desired operation
FEEDBACK
0V
10V
FEEDBACK
0V
10V
NO OPERATION
Parameter
Value
Process unit
Transmitter low limit
Transmitter high limit
Desired operation
FEEDBACK
2V
10V
FEEDBACK
2V
10V
NO OPERATION
Cascade Controller Option

Two feedback signals and two setpoints:

Similar to two feedback signals and one setpoint, the
need for two feedback signals with two setpoints is
frequently encountered. Whenever two critical zones
do not have the same setpoint value, two feedback
with two setpoint control is required. Many pumping
systems require the monitoring and control of two
loads that differ in size and pressure drop. Or this
can be effective when controlling different temperature
zones in cooling or heating applications.
To enable this setup, the feedback function in
parameter 417, Feedback Function, is selected. When
selecting 2-zone Minimum in parameter 417, the drive
will regulate the system so the feedbacks are equal to
or greater than their associated setpoints. If 2-zone
Maximum is selected, the feedbacks will be equal
to or less than their associated setpoints.
Feedback 1 is associated with Setpoint 1 and
Feedback 2 is associated with Setpoint 2. The two
independent groupings are continuously monitored
to satisfy both zones requirements.
Transmitter connection to the VLT:
The transmitters are connected to the VLT in the
same way as shown above with 1 setpoint and 2
feedbacks. The feedback connected to terminal 53
is assigned to setpoint 1 and the one connected to
terminal 54 to setpoint 2. Both transmitters must
have the same output signal and range.
Programming example for 2 feedback and
2 setpoint controls:
55