Lenze 4800 Manual page 108

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Adjustment of the field weakening operation:
1. Enter I
2. Selection of 100% n
3. Increase n
There is a PT1 element with an adjustable time constant between armature current
controller and field current controller. With this PT1 element the two circuits can
be decoupled.
The time constant is set to 140 ms as standard. For standard applications the time
must not be adjusted.
If the field control circuit is unstable in field weakening operation, increase or
decrease the time constant of the PT1 element.
FIG 7-6
Code Name
C079* PT1
element
Time
constant
for field
controller
attenuation
In general, the time constant is to be increased if the field current oscillates. As a
result, the dynamic response of the system is reduced.
under C231 (10...100% ref. to I
Fmin
at X1/8.
set
under C011 until reaching the required speed.
max
Signal flow chart (section) for the field control circuit with Vdown limitation
Possible settings
Lenze Selection
140 30 ms {10 ms}
ms
Configuration
).
Frated
Info
9000 ms The higher the time constant, the higher
the decoupling degree between aramture
and field control circuits.
4900Str033
48XX/49XXSHB0399
7-17