Film Blowing machine frequency converter in the production process will often jump off, the main reason is that the frequency of low heat loss of motor heating, ordinary motor own wind-blade low frequency when the heat is not enough. The heating temperature is insufficient to boot overload caused the inverter to jump or burn the motor. Frequency converter parameter adjustment improper also can jump.
The choice of motor
First of all, the load should be based on the required average power, the highest power, converted to the motor shaft side (may have reducer, pulley and other deceleration devices) to select the power of the motor, but also to consider the overload capacity of the motor. Motor manufacturers can provide the torque characteristic curve of the motor, the characteristics of the motor will change at different temperatures.
By the way: the order of choice of course is to select the motor and then choose the inverter according to the motor, because the ultimate goal of control is not the inverter nor the motor, but the mechanical load.
Second, frequency converter selection
First, it should be emphasized that the current selection should be based on. For general load, can be selected according to the rated current motor inverter, that is, the frequency converter rated current (that is, the maximum continuous operating current under the normal environment) is larger than the motor rated current can be. However, the emergence of extreme conditions must be considered. Therefore, the inverter also needs to provide a short period of overload current.
(Note: The electrical current is determined by the mechanical load)
The inverter has an overload current curve, which is an inverse time curve, which describes the relationship between overload current and time. This is the frequency converter manufacturers often say overload capacity can reach 150% rated current 2 seconds, 180% rated current 2 seconds and so on, is actually a curve. Therefore, as long as the current curve of the motor in the inverter overload current curve, is the correct selection. This is why sometimes the inverter power is greater than the motor power 1 or 2 gear (such as lifting applications), sometimes small power inverter can still drive high-power motor (such as conveyor belt) reasons.
Another must note: In an abnormal environment, for example, high altitude, high ambient temperature (for example, more than 50 degrees less than 60 degrees), side-by-side installation (some of the inverter installed side by bit, some to reduce capacity, according to the inverter design decision) and so on, to consider the reduction of frequency converter. This information inverter manufacturers can provide.
The result is that the rated power of the inverter may be greater than the motor power, or less than the motor power, in fact, the selection of inverter is also based on the mechanical load.
Conclusion: The final basis of the inverter selection is the current curve of the inverter, including the mechanical load.
Three, Y-type motor and inverter motor
Y-type motor, it should be ordinary asynchronous motor (impression is, not quite sure).
The fundamental function of the inverter is to change the power frequency, thus changing the speed of the motor. So theoretically, no matter what the motor, as long as you can change the frequency of speed, you can use the inverter.
Inverter Motor has a special design, more suitable for frequency conversion use
Therefore, there is not a separate fan is the so-called inverter motor.
When using inverter to control ordinary asynchronous motor, it is necessary to note:
1, low frequency (generally less than 25hz), as the motor uses coaxial fan, low speed cooling effect will be very poor, motor fever, torque characteristics become soft, resulting in speed instability, large current problems.
2, high-frequency (generally greater than 50hz), to see whether the motor can withstand high speed, such as bearing heating, dynamic balance is not good.