OC8 I²xt overload advance warning
Lenze · 9300 Series
What does x018 mean?
This is an advance warning indicating frequent and excessively long acceleration processes with motor overcurrent, or permanent motor overload where the motor current (Imotor) exceeds the rated motor current (Irmotor). This condition suggests that the drive or motor dimensioning may be inadequate, and continuous operation without addressing it could lead to an OC6 trip. This warning is managed by parameter C0606.
Common Causes
- Motor current (Imotor) consistently operating close to or slightly above the motor's rated current (C0091), triggering the warning threshold.
- Frequent transient current spikes during acceleration/deceleration due to short ramp times (C0012, C0013), accumulating I²xt thermal stress.
- Inadequate motor cooling due to blocked ventilation ducts, dirty fan, or high ambient temperature (e.g., >40°C) around the motor.
- Slight mechanical binding or increased friction in the load, causing a marginal increase in continuous current demand.
Repair Steps & Checklist
Click steps to track your progress.
- 1
Measure the actual motor current (e.g., clamp meter on output phase U) and compare it to the motor rated current (C0091).
- 2
Inspect the motor's cooling fan and heatsink for dust accumulation or obstruction, ensuring clear airflow.
- 3
Slightly increase the acceleration and deceleration times (C0012, C0013) to reduce peak currents during dynamic operation.
- 4
Verify ambient temperature around the motor and ensure it is within specified limits for continuous operation (e.g., consult C0061 thresholds).
- 5
Review the load profile to identify any periods of high continuous torque demand or very frequent start/stop cycles.