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How should the high-voltage motor and soft-start cabinet be matched?
How should the high-voltage motor and the soft-start cabinet be matched?


In principle, the selection of the high-voltage motor starting cabinet should be larger than the capacity of the driven motor. The rated capacity of the motor soft-starting cabinet usually has two nominals: one is nominally based on the power of the corresponding motor; the other is nominally based on the maximum allowable current of the soft-starting cabinet. The configuration of high-voltage motor and soft-start cabinet should pay attention to the following conditions:


In the following cases, the soft starter should increase the capacity.


1. Soft starters or soft starters that use energy-saving control are often run under heavy load. It may cause the overload of the soft starter, so the capacity of the soft starter should be increased.


2. The motor is used for continuous variable load or intermittent load, and the cycle is short. In this case, the motor is not allowed to run overloaded for a short time. Otherwise, the starter may be overloaded during operation, so the capacity should be increased.


3. If the motor is used for repeated short-time work, and the cycle is less than the starting time interval specified by the manufacturer, the soft starter may be overloaded during the starting period, so the capacity of the soft starter should be increased.


4. Some loads are too heavy, or the capacity of the power grid is too small. When starting, the starting time of the motor is too long, which makes the soft starter overload and trip. On the premise that the motor will not be damaged, the capacity of the soft starter can be appropriately enlarged.


5. For loads with special requirements for acceleration time, the length of motor acceleration time is a relative concept with inertia. Some loads require a short acceleration time, and the acceleration current of the motor will be relatively large. At this time, the capacity of the soft starter can be appropriately enlarged.


6. The load with large inrush current during the transition process may cause overcurrent protection action, and the capacity of the soft starter can be appropriately enlarged.


The motor adopts direct starting, and the starting current is 7 times that of the motor's full-load working current, which will cause excessive line voltage drop on the bus, causing rapid and short-term voltage fluctuations in the power supply and bus system connected to the motor, affecting the system. The normal operation of other electrical equipment. Therefore, the motor soft start cabinet is selected as the motor start control device.