WEG CFW500 trips F0072 (Motor Overload) after a motor change, why?
Our WEG CFW500 inverter is tripping F0072 (Motor Overload) on a conveyor motor we just replaced. It runs fine for a while, then trips. What should I check first?
Fault F0072 indicates that the inverter's motor overload function (Ixt) has detected excessive winding heating, estimated by integrating the output current above the set overload current. This can happen during sustained operation above the motor's overload current, with a heavy or jammed load, or after a restart if the motor hasn't cooled. The Ixt value is stored in non-volatile memory, so a motor that tripped may trip again soon after a restart.
Likely causes and checks
1Motor overload current parameters (P0156, P0157, P0158) are set too low.
- Points to it
- The inverter's motor overload protection relies on these parameters to define the motor's overload current at different speeds. If they are set lower than the actual operating current of the motor, especially after a motor change, the inverter will incorrectly detect an overload.
- Check
- Compare the values in P0156, P0157, and P0158 with the rating plate of the newly installed motor. WEG recommends setting P0156 approximately 10% above the motor's rated current (P0401).
2Overload on the motor shaft.
- Points to it
- A heavy or jammed load on the driven machine can cause the motor to draw excessive current, leading to an overload condition. The inverter's Ixt function will detect this sustained high current and trip F0072.
- Check
- Observe the motor current in P0003 and the overload level in P0037. If P0037 climbs steadily and alarm A0046 appears before the trip, inspect the driven machine for any signs of overload, binding, or changes in the process that could increase the load.
Next check: First, verify that parameters P0156, P0157, and P0158 are correctly set according to the new motor's rating plate, ensuring P0156 is about 10% above P0401. If the settings are correct, then check for any mechanical overload on the conveyor system.
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