Mitsubishi Electric FR-F800 Series Instruction Manual page 598

 Warning
Output is not shut off when a protective function is activated.
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
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OL
Stall prevention (overcurrent)
• When the output current of the inverter increases, the stall prevention (overcurrent) function is activated.
• The following section explains about the stall prevention (overcurrent) function.
When the inverter output current exceeds the stall prevention level (Pr.22 Stall
prevention operation level, etc.), this function stops the increase in frequency until the
During acceleration overload current decreases to prevent the inverter from resulting in overcurrent trip.
When the overload current is reduced below stall prevention operation level, this function
increases the frequency again.
When the inverter output current exceeds the stall prevention level (Pr.22 Stall
prevention operation level, etc.), this function decreases the frequency until the
During constant-
overload current decreases to prevent the inverter from resulting in overcurrent trip.
speed operation
When the overload current is reduced below stall prevention operation level, this function
increases the frequency up to the set value.
When the inverter output current exceeds the stall prevention level (Pr.22 Stall
prevention operation level, etc.), this function stops the decrease in frequency until the
During deceleration overload current decreases to prevent the inverter from resulting in overcurrent trip.
When the overload current is reduced below stall prevention operation level, this function
decreases the frequency again.
• Check that the Pr.0 Torque boost setting is not too large.
• The Pr.7 Acceleration time and Pr.8 Deceleration time settings may be too short.
• Check that the load is not too heavy.
• Check for any failures in peripheral devices.
• Check that the Pr.13 Starting frequency is not too large.
• Check that Pr.22 Stall prevention operation level is appropriate.
• Gradually increase or decrease the Pr.0 setting by 1% at a time and check the motor status. (Refer to
551.)
• Set a larger value in Pr.7 and Pr.8. (Refer to
• Reduce the load.
• Try Advanced magnetic flux vector control.
• Change the Pr.14 Load pattern selection setting.
• The stall prevention operation current can be set in Pr.22 Stall prevention operation level. The acceleration/
deceleration time may change. Increase the stall prevention operation level with Pr.22 Stall prevention
operation level, or disable stall prevention with Pr.156 Stall prevention operation selection. (Use Pr.156 to
set either operation continued or not at OL operation.)
oL
Stall prevention (overvoltage)
• When the output voltage of the inverter increases, the stall prevention (overvoltage) function is activated.
• The regeneration avoidance function is activated due to excessive regenerative power of the motor. (Refer to
page 572.)
• The following section explains the stall prevention (overvoltage) function.
If the regenerative power of the motor becomes excessive to exceed the regenerative
During deceleration power consumption capability, this function stops decreasing the frequency to prevent
overvoltage trip. As soon as the regenerative power has reduced, deceleration resumes.
• Check for sudden speed reduction.
• Check if the regeneration avoidance function (Pr.882 to Pr.886) is being used. (Refer to
The deceleration time may change. Increase the deceleration time using Pr.8 Deceleration time.
TH
Electronic thermal relay function pre-alarm
Appears if the cumulative value of the electronic thermal O/L relay reaches or exceeds 85% of the preset level
of Pr.9 Electronic thermal O/L relay. If the specified value is reached, the protection circuit is activated to shut
off the inverter output.
• Check for large load or sudden acceleration.
• Check that the Pr.9 setting is appropriate. (Refer to
• Reduce the load and frequency of operation.
• Set an appropriate value in Pr.9. (Refer to
search engine
FR-LU08 indication OL
page 228.)
FR-LU08 indication oL
FR-LU08 indication TH
page 266.)
page 266.)
6.5 Causes and corrective actions
page
page 572.)
6. PROTECTIVE FUNCTIONS
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