The inverter is easy to cause the motor to burn out? why?
Why does the inverter burn the motor?
The heat dissipation of the ordinary asynchronous motor is based on the fan air cooling behind the motor butt. If it is operated for a long time at a low frequency (that is, it is running below the rated frequency of the motor for a long time, the fan speed of the motor is low, so that the motor is not well cooled, too hot. The motor will burn out. If the motor has a problem, the motor current will increase. If the maximum current of the inverter is exceeded, the inverter will implement a protection stop output and report a fault code to the user.
The inverter shows that OC means overcurrent. The solution is to replace the motor with a special motor for frequency conversion, or add a cooling fan to the motor. Or it is a motor with a larger power.
What are the causes of the motor burning caused by the inverter?
The fault of the motor is actually not the cause of the motor itself. Most of them are caused by the non-standard debugging of the inverter or the use of the non-inverter motor when the inverter motor is used. The main reasons are as follows:
1. Use ordinary motor as variable frequency motor.
Since the ordinary motor cooling fan is connected with the rotating shaft, when the inverter is used for speed regulation, the speed is unstable, and the rated speed of the motor cannot be reached. The cooling fan can not play a normal role, causing the motor to dissipate heat badly; plus the ordinary motor is not Designed according to the frequency conversion requirements, so that the motor heats up or burns.
2. The variable frequency motor and the inverter are directly connected together without being debugged.
The two most common methods used by the inverter to control the motor are vector control and V/F curve control. Each type of control must first type the motor (synchronous, asynchronous, with or without encoder), motor rated power, rated voltage, and rated. The current, the speed or the number of poles, the rated frequency, the maximum operating frequency, the acceleration and deceleration time of the motor starting and stopping, the protection mode of the inverter control motor, the protection proportional coefficient, and the carrier frequency are all set. After these parameters are set, select whether it is vector control or V/F control. When vector control is selected, the motor must be idling with the inverter to dynamically self-learn or static self-learning with load. After self-learning, the motor can cooperate with the inverter to achieve the accuracy of vector control; when V/F control is selected, Self-learning is required, and the parameters are adjusted and then directly powered on.
3. The running direction of the inverter motor fan is inconsistent with the direction of rotation indicated on the fan. The fan can not function, causing the heat dissipation condition of the motor to deteriorate, and the heat generated by the motor can not be emitted, causing the motor to heat up or burn out.
4, 2 or 3 of the above three cases occur the most
When the motor current setting in the inverter is too large, the motor protection parameter setting is too large. When the motor is overloaded, the inverter cannot protect the motor according to the actual current of the motor, thus causing the motor to overload or burn.
When the motor speed setting is not correct, if the set speed exceeds the rated motor speed, the motor will run at a higher speed in the constant power zone at the rated frequency. The higher the speed, the smaller the output torque, causing the motor current to pass. Great heat or burned the motor;
If the motor acceleration/deceleration time is too short, the inverter will report overcurrent fault and protect it;
The frequency converter adopts vector control, but the self-learning of the motor and the frequency converter does not match, causing the parameters of the inverter control motor to be inconsistent with the actual value of the motor, causing the control precision to deteriorate, and the motor is heated or burned;
When the carrier frequency setting is relatively high, the switching rate of the inverter switch tube is relatively high, and the heat generation is increased. At this time, the ability of the inverter to resist the change of the load current is reduced. When the load current increases, the inverter may overcurrent trip. The phenomenon reflected on the surface is that the motor has a problem;
The motor protection current is not set. The default protection current of the inverter is 150% of the rated output current of the inverter. The inverter will protect only when the motor current reaches this value. The output current of the inverter is greater than the rated current of the motor. When the current of the motor reaches the protection current of the inverter, the motor is actually overloaded by more than 150%. The motor is severely heated and burned. The phenomenon that the customer sees is that the inverter has no problem and the motor quality is unreliable.
5. In view of the above situation, it is recommended that the customer choose the inverter to control the motor, the inverter motor should be selected, and the inverter selects the manufacturer with good quality. Although the initial investment is a little higher, the quality is guaranteed, the fault-free operation time is long, and it is not easy to cause the cause. The shutdown of the motor or the inverter caused by the failure, and the good quality of the inverter after-sales service is guaranteed, the response time is fast.
