Mitsubishi Electric FR-A720-0.4K Instruction Manual page 152

Operation Panel
Indication
Name Inverter overload trip (electronic thermal relay function)
If a current not less than 150% of the rated output current flows and overcurrent trip does not occur
Description
(220% or less), the electronic thermal relay activates to stop the inverter output in order to protect the
output transistors. (Overload capacity 150% 60s, inverse-time characteristic)
· Check that acceleration/deceleration time is not too short.
· Check that torque boost setting is not too large (small).
Check point
· Check that load pattern selection setting is appropriate for the load pattern of the using machine.
· Check the motor for use under overload.
· Increase acceleration/deceleration time.
· Adjust the torque boost setting.
Corrective action
· Set the load pattern selection setting according to the load pattern of the using machine.
· Reduce the load weight.
Operation Panel
Indication
Name Motor overload trip (electronic thermal relay function)
The electronic thermal relay function in the inverter detects motor overheat due to overload or reduced
cooling capability during constant-speed operation and pre-alarm (TH display) is output when the
integrated value reaches 85% of the Pr. 9 Electronic thermal O/L relay setting and the protection circuit is
Description
activated to stop the inverter output when the integrated value reaches the specified value. When
running a special motor such as a multi-pole motor or multiple motors, provide a thermal relay on the
inverter output side since such motor(s) cannot be protected by the electronic thermal relay function.
· Check the motor for use under overload.
· Check that the setting of Pr. 71 Applied motor for motor selection is correct. (Refer to Chapter 4 of
Check point
· Check that stall prevention operation setting is correct.
· Reduce the load weight.
· For a constant-torque motor, set the constant-torque motor in Pr. 71 Applied motor.
Corrective action
· Check that stall prevention operation setting is correct. (Refer to Chapter 4 of
*1 Resetting the inverter initializes the internal thermal integrated data of the electronic thermal relay function.
Operation Panel
Indication
Name
Heatsink overheat
If the heatsink overheats, the temperature sensor is actuated to stop the inverter output.
The FIN signal can be output when the temperature becomes approximately 85% of the heatsink
overheat protection operation temperature.
Description
For the terminal used for the FIN signal output, assign the function by setting "26" (positive logic) or
"126" (negative logic) in any of Pr. 190 to Pr. 196 (output terminal function selection). (Refer to Chapter 4 of
· Check for too high surrounding air temperature.
· Check for heatsink clogging.
Check point
· Check that the cooling fan is stopped. (Check that
· Set the surrounding air temperature to within the specifications.
Corrective action
· Clean the heatsink.
· Replace the cooling fan.
Operation Panel
Indication
Name Instantaneous power failure
If a power failure occurs for longer than 15ms (this also applies to inverter input shut-off), the
instantaneous power failure protective function is activated to trip the inverter in order to prevent the
control circuit from malfunctioning. If a power failure persists for longer than 100ms, the fault output is
not provided, and the inverter restarts if the start signal is ON upon power restoration. (The inverter
Description continues operating if an instantaneous power failure is within 15ms.) In some operating status (load
magnitude, acceleration/deceleration time setting, etc.), overcurrent or other protection may be
activated upon power restoration.
When instantaneous power failure protection is activated, the IPF signal is output. (Refer to Chapter 4 of
Check point
Find the cause of instantaneous power failure occurrence.
· Remedy the instantaneous power failure.
· Prepare a backup power supply for instantaneous power failure.
Corrective action
· Set the function of automatic restart after instantaneous power failure (Pr. 57). (Refer to Chapter 4 of
E.THT
E.THM
the Instruction Manual (Applied).)
Manual (Applied).)
E.FIN
the Instruction Manual (Applied))
E.IPF
the Instruction Manual (Applied))
the Instruction Manual (Applied).)
Causes and corrective actions
FR-PU04
Inv. Ovrload
FR-PU07
*1
FR-PU04
Motor Ovrload
FR-PU07
*1
FR-PU04
H/Sink O/Temp
FR-PU07
is displayed on the operation panel.)
FR-PU04
Inst. Pwr. Loss
FR-PU07
the Instruction
4
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