Mitsubishi Electric 800 Series Instruction Manual page 574

 Warning
Output is not shut off when a protective function activates.
Abbreviation OL
Name Stall prevention (overcurrent)
Description • When the output current of the inverter increases, the stall prevention (overcurrent) function activates.
• The following section explains about the stall prevention (overcurrent) function.
During
acceleration
During constant-
speed operation
During
deceleration
Check point • 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.
Corrective action • Gradually increase or decrease the Pr.0 setting by 1% at a time and check the motor status. (Refer to
• Set a larger value in Pr.7 Acceleration time and Pr.8 Deceleration time. (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
Abbreviation oL
Name Stall prevention (overvoltage)
Description • When the output voltage of the inverter increases, the stall prevention (overvoltage) function activates.
• The regeneration avoidance function activates due to excessive regenerative power of the motor. (Refer to
• The following section explains the stall prevention (overvoltage) function.
During deceleration
Check point • Check for sudden speed reduction.
• Check if the regeneration avoidance function (Pr.882 to Pr.886) is being used. (Refer to
Corrective action The deceleration time may change. Increase the deceleration time using Pr.8 Deceleration time.
Abbreviation TH
Name Electronic thermal relay function pre-alarm
Description 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 point • Check for large load or sudden acceleration.
• Check that the Pr.9 setting is appropriate. (Refer to
Corrective action • Reduce the load and frequency of operation.
• Set an appropriate value in Pr.9. (Refer to
When the output current of the inverter exceeds the stall prevention level (Pr.22 Stall
prevention operation level, etc.), this function stops the increase in frequency until the
overload current decreases to prevent the inverter from resulting in overcurrent trip. When
the overload current has reduced below stall prevention operation level, this function
increases the frequency again.
When the output current of the inverter exceeds the stall prevention level (Pr.22 Stall
prevention operation level, etc.), this function reduces frequency until the overload
current decreases to prevent the inverter from resulting in overcurrent trip. When the
overload current has reduced below stall prevention operation level, this function
increases the frequency up to the set value.
When the output current of the inverter exceeds the stall prevention level (Pr.22 Stall
prevention operation level, etc.), this function stops the decrease in frequency until the
overload current decreases to prevent the inverter from resulting in overcurrent trip. When
the overload current has decreased below stall prevention operation level, this function
decreases the frequency again.
538.)
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.)
page 559.)
If the regenerative power of the motor becomes excessive to exceed the regenerative
power consumption capability, this function stops decreasing the frequency to prevent
overvoltage trip. As soon as the regenerative power has reduced, deceleration resumes.
FR-LU08 OL
FR-PU07
FR-LU08 oL
FR-PU07
FR-LU08 TH
FR-PU07
page 230.)
page 230.)
6.4 Causes and corrective actions
page
page 190.)
page 559.)
6. PROTECTIVE FUNCTIONS
3
4
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8
9
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