Danfoss VLT AutomationDrive FC 361 - Page 139

4.13.7 No Trip at Inverter Overload
In some systems, the frequency converter has not been
sized properly to yield the current needed in all points of
the operational ow-head characteristic. At these points,
the motor needs a current higher than the rated current of
the frequency converter. The frequency converter can yield
110% of the rated current continuously for 60 s. If still
overloaded, the frequency converter normally trips
(causing the motor to stop by coasting) and issues an
alarm.
110
130BA260.10
105
100
95
60s
100
90.7
98
Current
% of rated
Time
Desired current>100%
Inverter
load
counter
Time
Warning Warning
~
~
Illustration 4.46 Output Current in Overload Condition
If the motor is unable to run continuously with the
demanded capacity, run it at reduced speed for a while.
Select parameter 14-61 Function at Inverter Overload to
automatically reduce motor speed until the output current
is below 100% of the rated current (set in
parameter 14-62 Inv. Overload Derate Current).
Parameter 14-61 Function at Inverter Overload is an
alternative to letting the frequency converter trip.
The frequency converter estimates the load on the power
section with an inverter load counter, which causes a
warning at 98% and a reset of the warning at 90%. At the
value 100%, the frequency converter trips and issues an
alarm.
Status for the counter can be read in
parameter 16-35 Inverter Thermal.
If parameter 14-61 Function at Inverter Overload is set to [3]
Derate, the motor speed is reduced when the counter
exceeds 98%, and stays reduced until the counter has
dropped below 90.7%.
If parameter 14-62 Inv. Overload Derate Current is set to for
example 95%, a steady overload causes the pump speed to
uctuate between values corresponding to 110% and 95%
of rated output current for the frequency converter.
14-61 Function at Inverter Overload
Option: Function:
Use in case of steady overload
beyond the thermal limits (110% for
60 s).
[0] * Trip Select [0] Trip to make the
frequency converter trip and issue
an alarm.
[1] Derate Reduces the motor speed to
decrease the load on the power
section and allowing it to cool
down.
14-62 Inv. Overload Derate Current
Range: Function:
95 %* [50 - 100 %] Enter the current level (in % of
rated output current for the
frequency converter) when running
with reduced motor speed after
load on the frequency converter
has exceeded the allowable limit
(110% for 60 s).
4.13.8 14-8* Options
14-89 Option Detection
Selects the behavior of the frequency converter when a change
in the option conguration is detected.
Option: Function:
[0] * Protect Option
Cong.
Freezes the current settings and
prevents unwanted changes when
missing or defective options are
detected.
[1] Enable Option
Change
Changes frequency converter
settings and is used when
modifying the system conguration.
This parameter setting returns to [0]
Protect Option Cong. after an
option change.
4.13.9 14-9* Fault Settings
14-90 Fault Level
This is an array parameter with 26 elements. Each of the bits can
be congured to any of the following options. Use this
parameter to customize fault levels.
Option: Function:
[0] O Use [0] O with caution as it
ignores all warnings and alarms for
the selected source.
[1] Warning
Parameter Descriptions Programming Guide
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