torque limit w12 danfoss

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Danfoss VFD (FC-102, FC-202, FC-302, or FC-51), Warning 12 (W12) stands for Torque Limit. This warning indicates that the motor has reached the maximum torque allowed by the drive's settings. While a Warning typically allows the drive to keep running (unlike an Alarm, which trips the motor), it will restrict the speed or current to protect the mechanical system.

torque limit w12 danfoss

 

Common Causes

  1. Mechanical Overload: The most likely cause. The motor is struggling to turn the load due to a jam, a blocked pump, a seized bearing, or heavy material on a conveyor.

  2. Acceleration is Too Fast: The Ramp-up time is too short. The drive is trying to get the motor up to speed faster than the physical load allows.

  3. Incorrect Motor Data: The drive was given the wrong nominal current or speed during initial setup, causing it to miscalculate the motor's true capacity.

  4. Limits Set Too Low: The software safety limits in the drive (Parameters 4-16 and 4-17) are set lower than what the application naturally requires.

How to Fix & Troubleshoot

1. Inspect for Mechanical Issues

Check the driven equipment. If it's a fan, check the dampers and belts; if it's a pump, check for clogs. If the motor is decoupled from the load and the warning disappears, the problem is mechanical.

2. Extend Ramp Times

If the warning only pops up during start-up or speed changes, your "Ramp-up" is too aggressive.

  • Increase Parameter 3-41 (Ramp 1 Ramp Up Time).

  • Increase Parameter 3-42 (Ramp 1 Ramp Down Time).

3. Adjust Torque Limit Parameters

If the application is safe to handle more force, you can increase the internal thresholds:

  • Parameter 4-16: Torque Limit Motor Mode (The "Pushing" force).

  • Parameter 4-17: Torque Limit Generator Mode (The "Braking" force).

  • Note: The default is often 110% or 160% depending on the drive type.

4. Verify Motor Settings

Ensure the drive has the correct info from the motor nameplate. If these are wrong, the drive "thinks" the motor is overloaded when it isn't.

  • Parameter 1-20 to 1-25: Confirm kW/HP, Voltage, Frequency, Current, and Speed match the motor plate.

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