Lenze 8200 motec frequency inverter 0.25kW-7.5kW - Manual (Page 94)

Function library
Limit value setting
7−23
L
EDB82MV752 EN 5.2
7.4.2 Current limits
Description
The controllers are equipped with a current−limit control which determines the dynamic response
under load. The measured load is compared with the limit values set under C0022 for motor load
and C0023 for generator load. If the current limit is exceeded, the controller will change its dynamic
behaviour:
Controller performance when a limit value is reached
Motor overload during acceleration:
The controller prolongs the acceleration ramp.
Generator overload during deceleration:
The controller prolongs the deceleration ramp.
With increasing load and constant speed:
·
When the current limit of the motor mode is reached:
– The controller reduces the output frequency to 0 Hz.
– The controller cancels the change of the output frequency if the load falls below the limit
value.
·
When the current limit in the generator mode is reached:
– The controller increases the output frequency up to the maximum frequency (C0011).
– The controller cancels the change of the output frequency if the load falls below the limit
value.
·
If suddenly a load is applied to the motor shaft (e.g. drive is blocked), the overcurrent
switch−off can be activated (error message OCX).
Codes for parameter setting
Code Possible settings IMPORTANT
No. Name Lenze Selection
C0022 I
max
limit (motor
mode)
150 30 {1 %} 150 Only 8200 vector 15 ... 90 kW:
If C0022 = 150 %, 180 % I
r
are available
for max. 3 s. after controller enable
^ 7−23
C0023 I
max
−limit in the
generator mode
150 30 {1 %} 150 C0023 = 30 %: function is inactive, if
C0014 = 2, 3:
^ 7−23
Adjustment
·
Set the acceleration and deceleration times so that the drive can follow the speed profile
without reaching I
max
of the controller.
·
C0022 and C0023 refer to the rated output current at a switching frequency of 8 kHz.
·
When operating with a switching frequency of 16 kHz you must adapt C0022 and C0023 to
the permissible output currents (derating).
·
Correct current control for operation in generator mode is only possible with external brake
resistor.
C0023 = 30 %
At V/f characteristic control the current−limit controller is not active for the operation in generator
mode with C0023 = 30%:
·
Possibly reasonable in applications with medium frequency asynchronous motors if motor
and generator mode cannot be detected as fault−free.
·
Drive behaviour in case of motor and generator overload (C0054 > C0022):
– The controller reduces the output frequency to 0 Hz.
– The controller cancels the change of the output frequency if the load falls below the limit
value.