Instruction manual

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4
PARAMETERS
4.2.11 Stall prevention and current limit (Pr. 22, Pr. 23, Pr. 66, Pr. 156)
Pr. 22 "stall prevention operation level"
Pr. 23 "stall prevention operation level compensation factor at double speed"
Pr. 66 "stall prevention operation level reduction starting frequency"
Pr. 156 "stall prevention operation selection"
• Stall prevention............If the current exceeds the stall prevention operation level, the
output frequency of the inverter is automatically varied to
reduce the current.
• Fast-response current limit.......... If the current exceeds the limit value, the output of
the inverter is shut off to prevent an overcurrent.
• Set the output current level (% to the rated inverter output current) at which the output
frequency will be adjusted to prevent the inverter from stopping due to overcurrent etc.
• For high-speed operation at or over the motor base frequency, acceleration may not
be made because the motor current does not increase.
To improve the operation characteristics of the motor in such a case, the stall
prevention level in the high-frequency range can be reduced. This is effective for
operation of a centrifugal separator up to the high-speed range. Normally, set 60Hz in
Pr. 66 and 100% in Pr. 23.
• For operation in the high-frequency range, the current in the locked motor state is
smaller than the rated output current of the inverter and the inverter does not result in
an alarm (protective function is not activated) if the motor is at a stop. To improve this
and activate the alarm, the stall prevention level can be reduced.
• You can make setting to prevent stall caused by overcurrent and/or to prevent the
inverter from resulting in an overcurrent trip (to disable fast-response current limit that
limits the current) when an excessive current flows due to sudden load fluctuation or
ON-OFF on the output side of a running inverter.
Parameter Number Factory Setting Setting Range Remarks
22 150% 0 to 200%
23 9999
0 to 200%,
9999
9999: Constant
according to Pr. 22
66 60Hz 0 to 400Hz
156 0 0 to 31, 100
Output frequency (Hz)
400Hz
Pr.66
Pr.22
Pr.23
Pr.23
=9999
Stall prevention operation level (%)
Reduction ratio
compensation
factor (%)
150
90
60
45
30
22.5
600 100 200 300 400
Setting example
(Pr.22=150%, Pr.23=100%, Pr.66=60Hz)
Current limit operation level (%)
Output frequency (Hz)