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PROTECTIVE FUNCTIONS
5
Operation Panel
Indication
E.OC3 FR-PU04 OC During Dec
Name Overcurrent shut-off during deceleration
Description
When the inverter output current reaches or exceeds approximately 200% of the
rated current during deceleration (other than acceleration or constant speed), the
protective circuit is activated to stop the inverter output.
Check point
Check for sudden speed reduction.
Check for output short circuit.
Check for too fast operation of motor's mechanical brake.
Corrective action
Increase the deceleration time.
Check mechanical brake operation.
Operation Panel
Indication
E.OV1 FR-PU04 OV During Acc
Name Regenerative overvoltage shut-off during acceleration
Description
A prealarm (RB indication) occurs if the inverter's internal main circuit DC voltage
reaches 85% of the specified value due to regenerative energy. If that voltage
reaches or exceeds the specified value, the protective circuit is activated to stop the
inverter output. It may also be activated by a surge voltage generated in the power
supply system.
Check point
Check for too slow acceleration. (e,g, during descending acceleration with lifting
load)
Corrective action Decrease the acceleration time.
Operation Panel
Indication
E.OV2 FR-PU04 Stedy Spd OV
Name Regenerative overvoltage shut-off during constant speed
Description
A prealarm (RB indication) occurs if the inverter's internal main circuit DC voltage
reaches 85% of the specified value due to regenerative energy. If that voltage
reaches or exceeds the specified value, the protective circuit is activated to stop the
inverter output. It may also be activated by a surge voltage generated in the power
supply system.
Check point Check for sudden load change.
Corrective action
• Keep load stable.
• Use the brake unit or power regeneration common converter (FR-CV) as required.
Operation Panel
Indication
E.OV3 FR-PU04 OV During Dec
Name Regenerative overvoltage shut-off during deceleration or stop
Description
A prealarm (RB indication) occurs if the inverter's internal main circuit DC voltage
reaches 85% of the specified value due to regenerative energy. If that voltage
reaches or exceeds the specified value, the protective circuit is activated to stop the
inverter output. It may also be activated by a surge voltage generated in the power
supply system.
Check point Check for sudden speed reduction.
Corrective action
• Increase the deceleration time. (Set the deceleration time which matches the
inertia moment of the load)
• Decrease the braking duty.
• Use the brake unit or power regeneration common converter (FR-CV) as required.
