In sea port, its a large container crane with 10kv high voltage on the machine.
1. Convert power into 400V AC three-phase by a transformer.
2. 400 V three-phase Alternating Current flow through the rectifier unit, convert into 500 volts Direct Current and put it to the DC bus.
3. The DC bus has multiple parallel inverters to drive each motor working.
4. In the second point, the rectifier unit integrates "energy feedback" function, to feed back the regenerate energy generated by the electric motor during descent or deceleration to power grid.

Questions:
1. Feedback to the power grid, what's the "grid" range? Limited to the whole sea port? Or will be fed back into the power supply source? Why?
2. The crane has energy feed back to the power grid, can it make the meter on the crane reversal? cause the company's total distribution room meter (Power Supply Bureau metering) reversal? how to achieve "energy saving" in energy feedback?