Lenze 8240 HVAC Series - Manual (Page 45)

Commissioning
5-5 UOOuhäáã~_^NMMO
5.3.3 Setting of the current limit (I
max
)
Code Name Possible settings IMPORTANT
Lenze Selection Info
C022 I
max
limit
motor mode
150 30 {1 %} 150
C023 I
max
limit
generator mode
80 30 {1 %} 150
Function 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 C022 for motor load and
under C023 for generator load. If the current-limit values are exceeded, the controller will change
its dynamic response.
Adjustment The acceleration and decleration time should be set short enough so that the drive can follow the
speed profile without reaching I
max
of the controller.
Drive characteristic when
reaching the limit value
D
During acceleration:
- Expansion of the acceleration ramp.
D
During deceleration:
- Expansion of the deceleration ramp.
D
When the load increases at constant speed:
- When the motor-current limit value is reached:
Reduction of the field frequency to 0.
- When the generator-current limit value is reached:
Increase the field frequency to the maximum frequency (C011).
- Stop the field-frequency change if the load falls below the limit value.
Important
D
In the generator mode the current can only be controlled correctly when you connect a brake unit
or in group drive with energy exchange.
D
For operation with chopper frequencies > 8 kHz, the current limit values should be set to the
currents ”I
max
for 60 s” indicated in the rated data (see chapter 3.3
. (Derating with higher chopper frequencies)
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