Siemens inverter F021 failure - Solutions - Huaqiang Electronic Network

Probe high frequency needle JTK-50L-Q has 5 needles in the high frequency needle

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Inverter F021 fault, find the manual prompts I2T monitoring exceeds the limit value, change the corresponding limit value of the motor, it will not alarm, I would like to ask the experts, what does I2T mean? Can you explain it in detail!
A: F021 -

Motor overheat protection, which is a malfunction in temperature monitoring. First of all, the more accurate setting parameter P383 (motor thermal time constant) is one of the most effective ways to avoid F021 false positives.

I2T, or "I squared T", stands for the current squared multiplied by time. It's a way to estimate the thermal energy generated in the motor windings. This value helps determine if the motor is overheating based on the current it's drawing over a given period.

The P383 parameter is used to define how quickly the motor heats up under load. For Siemens standard motors, this value is typically listed in the P383 table. If using motors from other manufacturers, it's best to refer to their technical specifications.

If you're confident that your motor isn't overloaded and the current is within normal limits, adjusting P383 to a higher value might help reduce unnecessary alarms. However, it's also important to check if the motor’s cooling system—like the fan—is functioning properly and that there’s adequate ventilation around the motor.

My personal recommendation is that if you're not using a Siemens original motor, it might be better to disable this I2T monitoring feature. Otherwise, you may encounter false alarms that aren’t actually related to real overheating issues.

Some engineers have suggested bypassing I2T protection altogether, as it can be too indirect and not always reliable. Most overload protection systems are based on direct current monitoring rather than I2T calculations. Relying solely on I2T isn't sufficient for accurate motor protection.

In many cases, motors come with built-in temperature sensors like PT100 or PTY embedded in the windings. These sensors feed data directly into the control system (such as a PLC), allowing for real-time temperature monitoring and display. Using the frequency converter alone to monitor motor temperature is becoming less common these days.

If your system has a higher-level control setup, consider connecting the PT100 signal directly to the monitoring system and disabling the inverter’s internal temperature alarm. This approach is more reliable and reduces the risk of false alarms. We've implemented this method in our projects, and it works well.

Setting P383 to 0 can effectively mask the F021 fault, preventing unnecessary interruptions due to false alarms. Users should evaluate whether this is the right approach for their specific application.