What is the role of frequency converter in air compressor?

We often talk about permanent magnet variable frequency air compressor, so what is the specific role of the frequency converter in the air compressor system? In fact, the frequency converter mainly protects the motor in the air compressor, including overcurrent protection, overload protection, short circuit protection, grounding protection, voltage protection and stall protection.

1. Over-current protection

When the motor’s current exceeds 150% of the rated value for 3 seconds, or 200% of the rated current for 10 microseconds, the inverter protects the motor by shutting down.

2. Overload protection

The frequency converter monitors the motor current. When the motor current exceeds 120% of the rated current/1 minute, the frequency converter protects the motor by shutting down.

3. Short circuit protection

After the inverter output is short-circuited, it will inevitably cause overcurrent, and the inverter will stop to protect the motor within 10 microseconds.

4. Ground protection

The frequency converter is equipped with a special grounding protection circuit, which is generally composed of a grounding protection transformer and a relay. When one or two phases are grounded, the frequency converter will alarm. Of course, if the user requires it, we can also design it to protect and shut down immediately after grounding.

5. Voltage protection

The output of the frequency converter has a voltage detection function, and the frequency converter can automatically adjust the output voltage so that the motor does not withstand overvoltage. Even when the output voltage adjustment fails and the output voltage exceeds 110% of the normal voltage, the inverter will protect the motor by shutting down. Similarly, when the voltage of the motor is lower than 90% of the normal voltage, the inverter will shut down for protection.

6. Stall protection

Stall protection is generally targeted at synchronous motors. For asynchronous motors, stalling during acceleration will inevitably manifest as overcurrent. The inverter realizes this protection function through overcurrent and overload protection. Stalling during deceleration can be avoided by setting a safe deceleration time during debugging.