The motor protection provided by frequency converters

During production, motors are often damaged due to improper operation, resulting in not only financial losses but also significant impacts on production schedules. Therefore, the correct use of frequency converters plays a crucial role in protecting motors. Our company summarizes the motor protection provided by frequency converters in motor conversion applications as follows:

**Overvoltage Protection**

The frequency converter has an output voltage detection function, automatically adjusting the output voltage to prevent the motor from experiencing overvoltage. Even if the output voltage adjustment fails or the output voltage exceeds 110% of the normal voltage, the frequency converter will still protect the motor by shutting down.

**Undervoltage Protection**

When the motor voltage drops below 90% of the normal voltage, the frequency converter will shut down for protection.

**Overcurrent Protection**

When the motor current exceeds 150% of the rated value for 3 seconds, or 200% of the rated current for 10 microseconds, the frequency converter will shut down to protect the motor.

**Phase Loss Protection**

The frequency converter monitors the output voltage. When a phase is lost, the frequency converter alarms, and after a period of time, shuts down to protect the motor.

**Reverse Phase Protection**

The frequency converter ensures the motor can only rotate in one direction, making it impossible to set the rotation direction unless the user changes the phase sequence of the motor's A, B, and C connections.

**Overload Protection**

The frequency converter monitors the motor current. When the motor current exceeds 120% of the rated current per minute, the frequency converter protects the motor by shutting down.

**Ground Protection**

The frequency converter is equipped with a dedicated ground protection circuit, typically consisting of a ground protection transformer and a relay. When one or two phases are grounded, the frequency converter alarms. Of course, if requested by the user, we can also design it to immediately shut down upon grounding.

**Short Circuit Protection**

A short circuit at the frequency converter output will inevitably cause overcurrent. Within 10 microseconds, the frequency converter protects the motor by shutting down.

**Overfrequency Protection**

The frequency converter has maximum and minimum frequency limiting functions, ensuring the output frequency remains within a specified range, thus achieving overfrequency protection.

**Stalling Protection**

Stalling protection is generally for synchronous motors. For asynchronous motors, stalling during acceleration inevitably manifests as overcurrent, which the frequency converter protects against through overcurrent and overload protection. Stalling during deceleration can be avoided by setting a safe deceleration time during commissioning.