Danfoss VLT 5000 Series Instruction Manual page 139

at which the process normally runs, which will enable
the required process conditions to be reached sooner.
Used together with Process control, closed loop (pa-
rameter 100).
Description of choice:
Set the required start frequency.
NOTE
If the adjustable frequency drive is running
at the current limit before the desired start
frequency is obtained, the process regu-
lator will not be activated. For the regulator
to be activated anyway, the start frequen-
cy must be lowered to the required output
frequency. This can be done during oper-
ation.
440 Process PID proportional gain
(PROC. PROP. GAIN)
Value:
0.00 - 10.00
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).
Description of choice:
Quick control is obtained by a high gain, but if the gain
is too high, the process may become unstable.
441 Process PID integral time
(PROC. INTEGR. T.)
Value:
0.01 - 9999.99 sec. (OFF)
Function:
The integrator provides an increasing gain at a con-
stant error between the set point and the feedback
signal. The greater the error, the quicker the gain will
increase. The integral time is the time needed by the
= factory setting, () = display text, [] = value for use in communication via serial communication port
136
VLT
integrator to reach the same gain as the proportional
gain.
The gain is proportional to the speed at which the error
changes.
Used together with Process control, closed loop (pa-
rameter 100).
Description of choice:
Quick control is obtained at a short integral time. How-
ever, this time may become too short, which can make
the process unstable.
If the integral time is long, major deviations from the
required set point may occur, since the process regu-
lator will take a long time to regulate in relation to a
given error.
442 Process PID differentiation time
(PROC. DIFF. TIME)
Value:
0.00 (OFF) - 10.00 sec.
Function:
0.01 The differentiator does not react to a constant error. It
only provides a gain when the error changes. The
quicker the error changes, the stronger the gain from
the differentiator.
The gain is proportional to the speed at which the error
changes.
Used together with Process control, closed loop (pa-
rameter 100).
Description of choice:
Quick control is obtained with a long differentiation
time. However, this time may become too long, which
can make the process unstable.
443 Process PID diff. gain limit
(PROC. DIFF. GAIN)
OFF
Value:
5.0 - 50.0
Function:
It is possible to set a limit for the differentiator gain. The
differentiator gain will increase if there are fast
changes, which is why it can be beneficial to limit this
gain, thereby obtaining a pure differentiator gain at
MG.51.C5.22 - VLT
®
5000 Series
is a registered Danfoss trademark.
0.00 sec.
5.0