Mitsubishi Electric FR-E720-600 Instruction Manual page 278

Causes and corrective actions
Operation panel
E.OV2
indication
Name
Regenerative overvoltage trip during constant speed
If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value,
Description
the protective circuit is activated to stop the inverter output. The circuit may also be activated by a surge voltage
produced in the power supply system.
1. Check for sudden load change.
Check point
2. Check that the Pr. 22 Stall prevention operation level is not lower than the no load current.
1. Keep load stable.
Check that regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) is used. (Refer to page 248).
Corrective action
Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.
2. Set a value larger than the no load current in Pr. 22 Stall prevention operation level.
Operation panel
E.OV3
indication
Name
Regenerative overvoltage trip during deceleration or stop
If regenerative energy causes the inverter's internal main circuit DC voltage to reach or exceed the specified value,
Description the protective circuit is activated to stop the inverter output. The circuit may also be activated by a surge voltage
produced in the power supply system.
Check point
Check for sudden speed reduction.
Increase the deceleration time. (Set the deceleration time which matches the moment of inertia of the load)
Longer the brake cycle.
Corrective action
Use regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886). (Refer to page 248).
Use the brake resistor, brake unit or power regeneration common converter (FR-CV) as required.
Operation panel
E.THT
indication
Name
Inverter overload trip (electronic thermal relay function)
If the temperature of the output transistor element exceeds the protection level under the condition that a current not
Description less than the rated inverter current flows and overcurrent trip does not occur (230% or less), the electronic thermal
relay activates to stop the inverter output. (Overload capacity 150% 60s, 200% 3s, inverse-time characteristic)
1. Check the motor for use under overload.
Check point
2. Check for too high ambient temperature.
1. Reduce the load weight.
Corrective action
2. Set the ambient temperature to within the specifications.
Operation panel
E.THM
indication
Motor overload trip (electronic thermal relay function) ∗1
Name
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 I
the Pr. 9 Electronic thermal O/L relay setting and the protection circuit is activated to stop the inverter output when the
Description
2
I t 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.
1. Check the motor for use under overload.
Check point
2. Check that the setting of Pr. 71 Applied motor for motor selection is correct. (Refer to page 111).
3. Check that stall prevention operation setting is correct.
1. Reduce the load weight.
Corrective action 2. For a constant-torque motor, set the constant-torque motor in Pr. 71 Applied motor.
3. Check that stall prevention operation setting is correct. (Refer to page 85).
∗1
Resetting the inverter initializes the internal thermal integrated data of the electronic thermal relay function.
276
FR-PU04
Stedy Spd OV
FR-PU07
FR-PU04
OV During Dec
FR-PU07
FR-PU04
Inv. Overload
FR-PU07
FR-PU04
Motor Ovrload
FR-PU07
2
t value reaches 85% of