Mitsubishi Electric FR-D720S SC EC, Instruction Manual

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Causes and corrective actions Troubleshooting
7 - 6
Warnings
When the protective function is activated, the output is not shut off.
Operation Panel
Indication
OL
FR-PU04
FR-PU07
OL
Name Stall prevention (overcurrent)
Description
During
acceleration When the output current of the inverter exceeds the stall prevention oper-
ation 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.
During
constant-
speed
operation When the output current of the inverter exceeds the stall prevention oper-
ation 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.
During
deceleration When the output current of the inverter exceeds the stall prevention oper-
ation 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.
Check point
Check that the Pr. 0 "Torque boost" setting is not too large.
Check that the Pr. 7 "Acceleration time" and Pr. 8 "Deceleration time" settings are not
too small.
Check that the load is not too heavy.
Are there any failure in peripheral devices?
Check that the Pr. 13 "Starting frequency" is not too large.
Check that the Pr. 22 "Stall prevention operation level" is appropriate.
Corrective action
Increase or decrease the Pr. 0 "Torque boost setting" 1% by 1% and check the motor
status. (Refer to section 6.2.1.)
Set a larger value in Pr. 7 "Acceleration time" and Pr. 8 "Deceleration time". (Refer to
section 6.6.1.)
Reduce the load weight.
Try advanced magnetic flux vector control and general-purpose magnetic flux vector
control.
Change the Pr. 14 "Load pattern selection" setting.
Set stall prevention operation current in Pr. 22 "Stall prevention operation level". (The
initial value is 150%.) 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". (Operation at OL
occurrence can be selected using Pr. 156.)
Operation Panel
Indication
oL
FR-PU04
FR-PU07
oL
Name Stall prevention (overvoltage)
Description
During
deceleration
If the regenerative energy of the motor becomes excessive and
exceeds the regenerative energy consumption capability, this function
stops the decrease in frequency to prevent over voltage shut-off. As
soon as the regenerative energy has decreased, deceleration resumes.
If the regenerative energy of the motor becomes excessive when
regeneration avoidance function is selected (Pr. 882 = 1), this function
increases the speed to prevent over voltage shut-off. (Refer to
section 6.19.4).
Check point
Check for sudden speed reduction.
Check that regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) is used.
(Refer to section 6.19.4.)
Corrective action
The deceleration time may change. Increase the deceleration time using Pr. 8 "Decelera-
tion time".