Evidence to watch
The function is proved by changed behavior, not by a parameter value alone.
- Commanded versus actual frequency
- Output current as percent of motor rating
- Overload accumulator and stall timer
F-41 · vendor-neutral function
VFD Current Limit and Stall Protection
Current limiting caps drive output current and therefore available motor torque. The drive may slow or extend acceleration instead of immediately tripping when the load demand reaches that limit.
Why it matters
The behavior behind the parameter.
A current limit can protect the drive and motor, but it cannot make an undersized system deliver more mechanical torque. Repeated limit operation is evidence to inspect load, sizing, ramps and motor data.
- Current limit acts before or alongside overcurrent and overload protection.
- The motor may fail to reach reference while the limit is active.
- Low-speed cooling and thermal duty still matter.
Interactive proof
Test vfd current limit and stall protection in three passes.
Keep the motor, load and starting condition constant. Change one function at a time, then use the electrical and mechanical evidence to explain the result.
- 01
Run the dynamometer with a moderate load and record rated current.
- 02
Increase load above the current-limit setting and compare current, speed error and torque.
- 03
Remove the overload cause and confirm normal acceleration before resetting any trip.
Common commissioning mistakes
These errors can make a healthy drive appear faulty or create a misleading test.
- Raising the limit to hide a jam or undersized motor.
- Confusing instantaneous overcurrent with thermal overload.
- Ignoring wrong nameplate current when interpreting percentage load.
Primary technical references
Transfer the concept; verify the exact drive.
This guide uses vendor-neutral terminology. For real equipment, use the manual for the installed model, option cards and firmware, plus the machine risk assessment and approved commissioning procedure.
Related VFD functions
D-01
VFD Fault Codes and Diagnostic Method
A VFD fault code identifies which protection function operated; it does not by itself prove the failed component. Diagnose with the code, first-changing measurement, trip history and machine condition together.
Read and test F-21V/Hz vs Sensorless Vector VFD Control
V/Hz control applies a frequency-to-voltage profile and is simple and robust. Sensorless vector control uses a motor model to regulate flux and torque more accurately, especially at low speed and changing load.
Read and test F-25VFD Flying Start Explained
Flying start—also called speed search or catch on the fly—estimates the speed and direction of an already rotating motor before the drive reapplies controlled torque.
Read and testFrom explanation to evidence