49
VLT
®
3500 HVAC
MG.35.B1.02 – VLT is a registered Danfoss trademark
Section 1Section 1Section 1Section 1Section 1
Section 2Section 2Section 2Section 2Section 2
Section 3Section 3Section 3Section 3Section 3
Section 4Section 4Section 4Section 4Section 4
★
= factory setting. Text in ( ) = display text. Figures in [ ] are used when communicating with the bus.
3.5.1 PID contr
oller
117 Display unit (DISPLAY UNIT)
Value:
★
% (standard)
[0]
°F
[21]
°C
[1]
PPM
[22]
PPM
[2]
in wg
[23]
Pa
[3]
bar
[24]
bar
[4]
RPM
[25]
RPM
[5]
gal/s
[26]
l/s.
[6]
ft
3
/s
[27]
m
3
/s.
[7]
gal/min.
[28]
l/min.
[8]
ft
3
/min.
[29]
m
3
/min.
[9]
gal/h
[30]
l/h
[10]
ft
3
/h
[31]
m
3
/h
[11]
lb/s
[32]
kg/s.
[12]
lb/min.
[33]
kg/min.
[13]
lb/h
[34]
kg/h
[14]
t/min.
[35]
t/h
[15]
ft
[36]
m
[16]
lb ft
[37]
Nm
[17]
ft/s
[38]
m/s.
[18]
ft/min.
[39]
m/min.
[19]
mVs
[40]
[20]
lb/in
2
[41]
Function:
Choose between different units that are to be shown
in the Display Mode together with the feedback value.
Scaling of the display read-out is carried out in para-
meters 115 and 116.
Description of choice:
See description of choice under parameter 115.
119 FF factor (FEED FWD FACTR)
Value:
0 - 500%
★
100%
Function:
This parameter is used in conjunction with PID
regulation. The FF function makes a large or small
proportion of the reference signal (setpoint) bypass
the PID regulator, which means that the PID regulator
only affects part of the control signal. Any change of
the setpoint will thus affect the motor rpm directly.
The FF factor ensures a high level of dynamism when
the setpoint is to be changed and guarantees a smal-
ler overshoot value.
Description of choice:
The feedforward factor is selected if the desired refe-
rence signal (setpoint) does not lead to the right start
frequency. The feedforward function determines the
start frequency proportional to the setpoint.
114 Feedback-signal (FEEDBACKSIGNAL)
Value:
Voltage input (VOLTAGE)
[0]
★
Current input (CURRENT)
[1]
Pulse input (PULSES)
[2]
Function:
This parameter allows a choice of process feedback
type by using the
Closed loop
, which is selected in
parameter 101.
Description of choice:
If the internal PID regulator is used, one of the inputs
on terminal 17 (parameter 401), terminal 53 (parame-
ter 412) or terminal 60 (parameter 413) is to be used
for the feedback signal.
By choosing one of these, the same type is disabled
as a reference signal.
115 Display value at min. feedback (FB)
(DIS VLU@MIN FB)
Value:
0 - 9999
★
0
Function:
Parameters 115 and 116 are used to scale a display
read-out which is proportional to a feedback transmit-
ter signal.
The value is displayed if feedback has been selected
in Display Mode.
Description of choice:
If a transmitter, for example, has a range of 6-10 bar,
6 can be programmed in parameter 115 and 10 in
parameter 116. In parameter 117 the unit of bar can
be chosen [4].
116 Display value at max. feedback (FB)
(DIS VLU@MAX FB)
Value:
0 - 9999
★
100
Function & Description of choice:
See function under parameter 115.
