Danfoss VT2800 Series Design Manual page 99

416 Process units
(REF/FEEDB. UNIT)
Value:
No unit (NO UNIT)
% (%)
ppm (PPM)
rpm (RPM)
bar (BAR)
Cycles/min (CYCLE/MI)
Pulses/s (PULSE/S)
Units/s (UNITS/S)
Units/min. (UNITS/MI)
Units/h (UNITS/H)
°C (°C)
Pa (PA)
l/s (L/S)
3 3
m /s (M /S)
l/min. (L/M)
3 3
m /min. (M /MIN)
l/h (L/H)
3 3
m /h (M /H)
Kg/s (KG/S)
Kg/min. (KG/MIN)
Kg/hour (KG/H)
Tons/min. (T/MIN)
Tons/hour (T/H)
Metres (M)
Nm (NM)
m/s (M/S)
m/min. (M/MIN)
°F (°F)
In wg (IN WG)
gal/s (GAL/S)
3 3
Ft /s (FT /S)
Gal/min. (GAL/MIN)
3 3
Ft /min. (FT /MIN)
Gal/h (GAL/H)
3 3
Ft /h (FT /H)
Lb/s (LB/S)
Lb/min. (LB/MIN)
Lb/hour (LB/H)
Lb ft (LB FT)
Ft/s (FT/S)
Ft/min. (FT/MIN)
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
= factory setting. () = display text [] = value for use in communication via serial communication port
MG.28.E9.02 - VLT is a registered Danfoss trademark
VLT
also as a unit for Minimum/Maximum reference
and Minimum/Maximum feedback.
Description of choice:
[0]
Select the required unit for the reference/feed-
[1]
back signal.
[2]
[3]
[4]
VLT 2800 Regulators
[5]
The VLT 2800 has two integrated PID regulators, one
[6]
to regulate speed and one to regulate processes.
[7]
Speed regulation and process regulation require
[8]
a feedback signal back to an input. There are a
[9]
number of settings for both PID regulators that are
[10]
made in the same parameters, but selection of
[11]
regulator type will affect the selections that have
[12]
to be made in the shared parameters.
[13]
In parameter 100 Configuration it is possible to select
[14]
regulator type, Speed regulation, closed loop [1]
[15]
or Process regulation, closed loop [3].
[16]
[17]
Speed regulation
[18]
This PID regulation is optimised for use in applications
[19]
in which there is a need to maintain a particular motor
[20]
speed. The parameters that are specific for the speed
[21]
regulator are parameter 417 to parameter 421.
[22]
Process regulation
[23]
The PID regulator maintains a constant process
[24]
mode (pressure, temperature, flow, etc.) and
[25]
adjusts the motor speed on the basis of the
[26]
reference/setpoint and feedback signal.
[27]
A transmitter provides the PID regulator with a
[28]
feedback signal from the process as an expression
[29]
of the process's actual mode. The feedback signal
[30]
varies as the process load varies.
[31]
This means that there is a variance between the
[32]
reference/setpoint and the actual process mode.
[33]
This variance is compensated by the PID regulator
[34]
by means of the output frequency being regulated
[35]
up or down in relation to the variance between the
[36]
reference/setpoint and the feedback signal.
[37]
[38]
The integrated PID regulator in the frequency converter
[39]
has been optimised for use in process applications.
[40]
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
®
2800 Series
99