VLT
®
FCD Series
m/min. (M/MIN)
[26]
°F (°F)
[27]
In wg (IN WG)
[28]
gal/s (GAL/S)
[29]
Ft
3
/s (FT
3
/S)
[30]
Gal/min. (GAL/MIN)
[31]
Ft
3
/min. (FT
3
/MIN)
[32]
Gal/h (GAL/H)
[33]
Ft
3
/h (FT
3
/H)
[34]
Lb/s (LB/S)
[35]
Lb/min. (LB/MIN)
[36]
Lb/hour (LB/H)
[37]
Lb ft (LB FT)
[38]
Ft/s (FT/S)
[39]
Ft/min. (FT/MIN)
[40]
Function:
Select among different units to be shown on the
display. The unit is read out if an LCP control
unit can be connected, and if
Reference [unit]
[2]
or
Feedback [unit]
[3] has been selected in one
of parameters 009-012
Display read-out
, and in
Display mode. The unit is used in
Closed loop
also as a unit for Minimum/Maximum reference
and Minimum/Maximum feedback.
Description of choice:
Select the required unit for the reference/feed-
back signal.
■
FCD 300 Regulators
The FCD 300 has two integrated PID regulators, one
to regulate speed and one to regulate processes.
Speed regulation and process regulation require
a feedback signal back to an input. There are a
number of settings for both PID regulators that are
made in the same parameters, but selection of
regulator type will affect the selections that have
to be made in the shared parameters.
In parameter 100
Configuration
it is possible to select
regulator type,
Speed regulation, closed loop
[1]
or
Process regulation, closed loop
[3].
Speed regulation
This PID regulation is optimised for use in applications
in which there is a need to maintain a particular motor
speed. The parameters that are specific for the speed
regulator are parameter 417 to parameter 421.
Process regulation
The PID regulator maintains a constant process
mode (pressure, temperature, flow, etc.) and
adjusts the motor speed on the basis of the
reference/setpoint and feedback signal.
A transmitter provides the PID regulator with a
feedback signal from the process as an expression
of the process
’
s actual mode. The feedback signal
varies as the process load varies.
This means that there is a variance between the
reference/setpoint and the actual process mode.
This variance is compensated by the PID regulator
by means of the output frequency being regulated
up or down in relation to the variance between the
reference/setpoint and the feedback signal.
The integrated PID regulator in the frequency converter
has been optimised for use in process applications.
This means that there are a number of special
functions available in the frequency converter.
Previously it was necessary to obtain a system
to handle these special functions by installing
extra I/O modules and programming the system.
With the frequency converter the need to install
extra modules can be avoided. The parameters
that are specific to the Process Regulator are
parameter 437 to parameter 444.
■
PID functions
Unit of reference/feedback
When
Speed regulation, closed loop
is selected
in parameter 100
Configuration
the unit of
reference/feedback is always rpm.
When
Process regulation, closed loop
is selected
in parameter 100
Configuration
the unit is defined
in parameter 416
Process units.
Feedback
A feedback range must be preset for both regulators.
At the same time this feedback range limits the
potential reference range so that if the sum of all
references lies outside the feedback range, the
reference will be limited to lie within the feedback range.
The feedback signal must be connected to a
terminal on the frequency converter. If feedback
✭
= factory setting. () = display text [] = value for use in communication via serial communication port
MG.04.B7.02 - VLT is a registered Danfoss trademark
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