VLT
®
5000 Series
Description of choice:
Fast control is obtained if the integral time is short.
However, this time may become too short, in which
case the process may become unstable.
437
437 Process PID Normal/inverse control
(PROC NO/INV CTRL)
Value:
✭Normal (NORMAL)
[0]
Inverse (INVERSE)
[1]
Function:
It is possible to choose whether the process regula-
tor is to increase/reduce the output frequency. This
is done by having a difference between the refer-
ence signal and the feedback signal.
Used together with
Process control, closed loop (pa-
rameter 100).
Description of choice:
If the VLT frequency converter is to reduce the out-
put frequency in case the feedback signal increases,
select Normal [0].
If the VLT frequency converter is to increase the out-
put frequency in case the feedback signal increases,
select Inverse [1].
NB!:
If Disable [0] is selected, it will mean that
when the error changes its sign, the integrator
will first have to integrate down from the level ob-
tained as a result of the former error, before any
change to the output frequency occurs.
438
438 Process PID anti windup
(PROC ANTI WINDUP)
Value:
Off (DISABLE)
[0]
✭On (ENABLE)
[1]
Function:
It is possible to select whether the process regulator
is to continue regulating on an error even if it is not
possible to increase/reduce the output frequency.
Used together with Process control, closed loop (pa-
rameter 100).
Description of choice:
The factory setting is Enable [1], which means that
the integration link is adjusted in relation to the ac-
tual output frequency if either the current limit or the
max./min. frequency has been reached. The pro-
cess regulator will not engage again until either the
error is zero or its sign has changed.
Select Disable [0] if the integrator is to continue
integrating on an error, even if it is not possible to re-
move the fault by such control.
NB!:
If Disable [0] is selected, it will mean that
when the error changes its sign, the integrator
will first have to integrate down from the level ob-
tained as a result of the former error, before any
change to the output frequency occurs.
439
439 Process PID start frequency
(PROC START VALUE)
Value:
f
MIN
-f
MAX
(parameter 201 and 202)
✭ parameter 201
Function:
When the start signal comes, the VLT frequency
converter will react in the form of Speed control,
open loop following the ramp. Only when the pro-
grammed start frequency has been obtained, will it
change over to Process control, closed loop .In
addition, it is possible to set a frequency that corre-
sponds to the speed at which the process normally
runs, which will enable the required process condi-
tions to be reached sooner.
Used together with Process control, closed loop (pa-
rameter 100).
Description of choice:
Set the required start frequency.
NB!:
If the VLT frequency converter is running
at the current limit before the desired start fre-
quency is obtained, the process regulator will not be
activated. For the regulator to be activated anyway,
the start frequency must be lowered to the required
output frequency. This can be done during operation.
440
440 Process PID proportional gain
(PROC. PROP. GAIN)
Value:
0.00 - 10.00
✭ 0.01
Function:
The proportional gain indicates the number of times
the error between the set point and the feedback
signal is to be applied.
Used together with Process control, closed loop (pa-
rameter 100).
✭
= factory setting. () = display text [] = value for use in communication via serial communication port
MG.51.A1.02 - VLT is a registered Danfoss trade mark
152
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