Cause : INVERSE TIME comes when prolonged overload condition, exceeding the Inverse Time allowance, has caused the trip.

Inverse Time fault in Parker AC690 drive typically relates to the drive's protection mechanism against prolonged overcurrent conditions. This fault is triggered when the motor draws current over a set threshold for a longer duration than is considered safe by the drive. The protection operates based on an inverse time characteristic—meaning the higher the current, the faster the fault will trip to protect the motor and drive from damage.

Possible Causes and Solutions:

1. Sustained Overcurrent Condition:

   • Cause: The motor may be operating under conditions where it continuously draws more current than its rated capacity, but not enough to immediately trigger an overcurrent fault.
   • Solution:
     • Check the motor load: Ensure that the load on the motor is within its rated capacity. Prolonged overloading can cause this fault.
     • Reduce the load: If the load is excessive, consider reducing it or resizing the motor and drive to handle the higher demand.

2. Inadequate Cooling:

   • Cause: The motor or drive may be overheating due to inadequate cooling, which can increase the current draw.
   • Solution:
     • Improve ventilation: Ensure that the motor and drive are properly ventilated and operating within their specified temperature ranges.
     • Check cooling fans and heat sinks: Make sure they are clean and functioning correctly to prevent overheating.

3. Incorrect Motor Settings:

   • Cause: The drive might have incorrect motor protection settings, leading to premature or incorrect triggering of the inverse time protection.
   • Solution:
     • Verify motor settings: Check that the motor protection settings, including the overload protection curve and current limits, are correctly configured according to the motor's specifications.

4. High Inertia Loads:

   • Cause: High inertia loads may cause the motor to draw excessive current for longer periods during startup or when changing speed.
   • Solution:
     • Adjust acceleration/deceleration times: Increase the ramp times to reduce the stress on the motor during these phases, which can help avoid prolonged overcurrent conditions.

5. Mechanical Issues:

   • Cause: Mechanical binding, friction, or misalignment in the motor’s load can cause it to draw more current over time.
   • Solution:
     • Inspect the mechanical system: Check for any mechanical issues, such as misalignment or binding, that might cause the motor to work harder than necessary.

6. Voltage Supply Issues:

   • Cause: Fluctuations in the voltage supply can cause the motor to draw more current, potentially triggering the inverse time protection.
   • Solution:
     • Check the supply voltage: Ensure that the voltage supply is stable and within the specified range for the drive. Address any fluctuations or instability in the power supply.