Lenze SMV VFD Fault Troubleshooting - Fault #8 - Overload Fault

Lenze SMV VFD Fault Troubleshooting - Fault #8 - Overload Fault

This article explains the Lenze SMV VFD Overload and CL Faults.
These faults can occur with both the non-Modbus or Modbus type VFD.
  1. Non-Modbus VFD's do NOT use CAT-5 cables for communication.
  2. Modbus (571) VFD's use CAT-5 cables for communication.
An overload fault will be displayed as F_PF on the VFD and in the VFD fault history (P500), while the fault will be displayed as Fault #08 on the equipment HMI.
If the VFD displays CL, this is also an indicator that there could be and overload condition.
CL stands for Current Limit and troubleshooting steps are similar to that of an overload fault.

Status / Warning
Cause
Remedy
CL - Current Limit (P171) Reached
Motor Overload
  1. Increase P171
  2. Verify drive/motor are proper size for application.

Common Causes:
  1. Incorrect wheel rotation
  2. Fan speed set too high.
  3. Grease buildup on fan wheel.
  4. Debris stuck in fan wheel.
  5. Motor locked/failed.
  6. VFD wired to the wrong fan.
  7. Duct not sized properly or installed incorrectly.

VFD Manuals / Troubleshooting Guide:

F_PF - Fault #08 - Thermal Overload - Overload Fault: The motor drew too much current for too long.

Ensure the motor overload parameter P108 is properly set: P108=Motor FLA x 100 / Drive Output Rating.

Many 230V/480V motors can be wired for either voltage. Check the motor to ensure the motor is wired for the correct voltage applied.

Ensure the fan is spinning in the correct direction.

Ensure the fan no mechanical problems (including if the fan is unbalanced/ vibrating).

If the fan is belt drive, ensure that there is proper belt tension.

Check the input power rating on the data plate of the drive. If the drive is rated for 3 phase power only, ensure that voltage is present on all three input phases to the drive.

Check the output phases of the drive with an amps clamp to ensure the motor is pulling current evenly on all three phases.

If it is not, check the phase to phase output voltage of the drive on all three phases to make sure the output voltage is balanced while the drive is running at a constant speed.

If the motor is drawing unevenly; however the phase to phase output voltage of the drive is balanced, replace the motor.

If the output phase to phase voltage has one or two phases off by half the measured voltage of the remaining phase while the drive is running at constant speed, replace the drive.