If you have had the privilege of participating in motor tests, you may have a deeper understanding of variable frequency technology. Especially those who have used the old test equipment can better appreciate the advantages of variable frequency technology.
Whether it is the inspection test or the type test of the motor, the motor starting process will be involved. Especially in the case where the motor power is relatively large and the grid capacity is relatively small, it will be quite difficult to start the motor without load. Since this is the case during the test process, one can imagine what it is like during the actual operation startup of the motor.
The locked-rotor test is a detection carried out when the motor rotor is in a stationary state, which is used to detect the starting characteristics and overload characteristics of the motor. For power-frequency motors, starting has always been a very crucial factor. Especially in some special situations, due to factors such as working condition requirements or equipment performance constraints, there is often only a power-frequency power source. Of course, power-frequency motors will also be selected.
對于不少的電機廠，特別是新購置或改進的試驗設備，也都采用了變頻電源，完全解決了電機的起動問題，但是，也有其弊端，也就是不能完全發現電機的性能弱勢。曾經有一批雙速電機，在制造廠家試驗時，未發現異常，但在使用方卻出現了在某一個轉速下無法起動的事實，進一步檢查發現，該電機試驗時只進行了一個轉速下的起動性能，而未能發現另一轉速下電機起動性能的不足，但電機實際使用過程中恰恰是在起動性能相對較差的對應轉速下起動。事實上，電機變頻起動時非常容易，這也是試驗時能起動而工頻運行條件下可能出問題的原因。
For many motor factories, especially those that have newly purchased or improved test equipment, variable frequency power supplies are also used, which completely solves the problem of motor starting. However, there are also some drawbacks, that is, it is not possible to fully detect the performance weaknesses of the motor.
There was once a batch of dual-speed motors. During the test in the manufacturing factory, no abnormalities were found. But in the user's place, it was a fact that the motors could not be started at a certain rotational speed. Further inspection revealed that during the test of these motors, only the starting performance at one rotational speed was tested, and the insufficient starting performance of the motors at the other rotational speed was not discovered. However, in the actual use process of the motors, they were exactly started at the corresponding rotational speed with relatively poor starting performance.
In fact, it is very easy to start the motor with variable frequency, which is also the reason why the motor can be started during the test but may have problems under the power frequency operation condition.
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