Siemens inverter F021 failure - Solutions - Huaqiang Electronic Network

I'm facing an Inverter F021 fault, and the manual mentions that I2T monitoring has exceeded the limit value. After adjusting the motor's corresponding limit value, the alarm disappears. I'd like to ask the experts: what exactly does I2T mean? Could you explain it in detail?

A: F021 is a motor overheat protection fault related to temperature monitoring. One of the most effective ways to prevent false triggering of F021 is to accurately set parameter P383, which represents the motor's thermal time constant.

I2T stands for "Current Squared Time." It's a parameter used to represent the thermal energy generated by the motor. Specifically, it's calculated as the square of the current multiplied by the time duration. This value helps the system estimate how much heat is being generated in the motor windings.

In the P383 table, Siemens provides thermal time constants for their standard motors. For motors from other manufacturers, you can refer to their technical specifications or contact the manufacturer for accurate values.

If you're confident that your motor isn't overloaded and the current is within normal limits, you can try increasing the P383 value slightly. However, it's also important to check if the motor fan is functioning properly and if the ventilation around the motor is adequate.

My personal recommendation is that if you're not using a Siemens original motor, it might be better to disable this I2T monitoring function altogether. This can help avoid unnecessary alarms and false trips, especially if you have a more advanced control system in place.

Some engineers suggest disabling I2T protection because it's more indirect compared to direct current-based overload protection. While I2T can provide some insight into thermal stress, it shouldn't be relied upon as the sole method of protection.

Normally, temperature sensors like PT100 or PTY are embedded inside the motor windings. These sensors send temperature data to a higher-level control system (such as a PLC), where it can be monitored, displayed, and used for protection. Relying solely on the inverter for temperature monitoring is becoming less common these days.

If you already have a more advanced control system, it’s best to connect the PT100 signal directly to that system and disable the inverter’s temperature alarm. We've done this in many projects, and it reduces false alarms while offering more accurate monitoring.

Setting P383 to 0 can effectively mask the F021 fault and prevent false alarms. This is something users should consider depending on their specific setup and needs.