What is the Difference between Inverter Overload and Overheating?

Frequency converter is a power control device that uses frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor's operating power supply.

Frequency converter is a power control device that uses frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor's operating power supply. The frequency converter is mainly composed of rectifier (AC to DC), filtering, inverter (DC to AC), braking unit, drive unit, detection unit, microprocessing unit, etc. By changing the frequency of the power supply, the purpose of changing the power supply voltage is achieved, and the power supply voltage required is provided according to the actual needs of the motor, thereby achieving the purpose of energy saving and speed regulation. In addition, the frequency converter also has many protection functions, such as overcurrent , overvoltage, overload protection, etc.

What is the difference between inverter overload and overheating? The causes of overcurrent are as follows:

First, under normal circumstances, if the current trips, the inverter will display an OC fault;
The second is that the inverter module is damaged. At this time, a fault will appear as soon as it is turned on. The module is defective, the output voltage is unbalanced, and the load current increases rapidly;
Third, the load torque increase is blocked, or the acceleration and deceleration time is improperly set, and the torque suddenly changes, causing the current to increase;
Fourth, the motor capacity does not match the frequency converter power. Generally, the motor power is too large and the frequency converter is too small.

Overload protection is a protective measure taken to prevent the load from being too powerful; overcurrent protection is a protective measure taken to prevent the current from being too large. Overload trip will sometimes display OC fault, and sometimes it will display OH fault. OH means over-temperature, poor heat dissipation of the inverter, and OH will be displayed when the module temperature rise reaches a certain value. Based on personal experience, current tripping and overload tripping are the above differences.
The cause of overcurrent limit violation is serious overload of the motor in a short period of time or other factors; the cause of overload limit violation is overload that causes the motor temperature rise to exceed the standard.
Frequency converter is a power control device that uses frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor's operating power supply. In order to protect the safe operation of the equipment during operation, the frequency converter will set current over-limit (over-current) protection and overload over-limit protection. When a limit violation occurs, corresponding measures are automatically taken, such as alarming or shutting down.

Overcurrent means that the current of the motor (inverter output) exceeds the specified value; overload means that the load of the motor exceeds the rated power of the motor. The main cause of overcurrent and overload is motor overload. The reason why it is divided into two indicators is:

1. The objects they protect are different. Overcurrent is mainly used to protect the frequency converter, while overload is mainly used to protect the motor. Because the capacity of the frequency converter is usually larger than the capacity of the motor. In this case, when the motor is overloaded, the inverter does not necessarily have overcurrent.
2. The rate of change of current is different. Overload protection occurs during the working process of production machinery, and the rate of change of current is usually small: other overcurrents other than overload are often sudden, and the rate of change of current is often large.
3. The methods of protection are different. Overload protection has inverse time characteristics. Overload protection is mainly to prevent the motor from overheating, so it has an "inverse time limit" characteristic similar to that of a thermal relay. That is to say, if it does not exceed the rated current by much, the allowed operating time can be longer, but if it exceeds the rated current by a large amount, the allowed operating time will be shortened. In addition, when the frequency decreases, the heat dissipation condition of the motor becomes worse.