For high-power motors, regardless of the method used for starting, the current remains the same in any case – so what’s the point? !
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Star-delta starting. Variable-frequency start. But the final operating current is the same; what’s the point of that? Impact resistance? ! Please give me some advice.
The meaning is completely different! The starting current of a motor is very different from its operating current – during startup, it must overcome inertial torque as well as driving torque, whereas during operation it only needs to overcome the driving torque. Some devices have extremely high inertial torque, and the current during startup is several times, or even a dozen times, that of normal operation; it is necessary to optimize the startup process. Large motors are expensive, the connecting equipment is costly as well; the load is heavy, there are issues related to insulation and current surges, plus bearings and shafts... It is necessary and cost-effective to use buffering mechanisms for starting large motors
There is also short-circuit current, which reduces the impact on the power grid
Large motors have very high starting currents, which can cause stress on the power grid.
Whether a star-delta connection, autotransformer, soft starter, or frequency converter is used to start a large motor, the effect is the same: high current during startup leads to a significant drop in grid voltage, and in severe cases this can cause other low-voltage devices in operation to trip. Therefore, for large motors with transformers of relatively small capacity, one of these starting methods should be employed.
The high starting current causes a significant drop in the bus voltage during startup; this is the root cause. Therefore, star-delta connection, frequency converters, or soft starters should be used to reduce the starting current.
Buffer start-up protection devices and the impact on the power grid during device startup
I believe reducing starting torque to protect rotating equipment is the top priority, with minimizing impact on the power grid being the second priority