There are six resistors and six capacitors. Two ends of the two resistors are respectively connected to just three groups of three-phase incoming wires, and the other two ends are respectively connected in series with one end of the capacitor. This connection can be resistance-capacitance buck or phase detection, depending on the object of output connection.

Your introduction, when the circuit involves the control circuit, if it is phase detection, it is necessary to connect the shaping trigger circuit and the comparison circuit.

Personally, I think it is a capacitor step-down circuit.

Resistance-capacitance step-down, generally used for pure resistance constant load, and low power. Its principle is to connect a small capacitor in series in the circuit, which is generally a nonpolar capacitor of about 0. 1uf, preferably an oil-immersed capacitor in iron shell. Because the capacitance is very small and the capacitive reactance is very large, it will consume a lot of voltage on the capacitor, thus reducing the voltage. The resistor is only used to discharge the capacitor.

The purpose of this practice is to save costs.

My humble opinion, I hope I can help you!