For the OP: what I have written below is for my electrical colleagues on the EF. You need someone to rewire afresh the whole machine which at the moment is an unsafe lash-up.
I have been studying the images the OP provided and have an alternative view on what has been wired.
Some assumptions:
1. The work lamp is 220Vac.
2. The motor is a
three phase squirrel cage motor which can be wired 380V star or 220V delta.
3. The original manufacturer's wiring was for 3 phase operation at 380V and the TPDT centre off rotary switch enables Reverse - Off - Forward rotation of the motor - there are clues to this if you study the rotary switch images, the classic positions of the 4 solid links and the chopped of blue and green wires. The motor was wired as star.
4. I reckon (cannot be certain) but the original machine lead was 3 wire and earth. The lamp obtained its 220V ( = 380/1.713) by connecting across a line and the virtual neutral at the start point of the motor. If the lead was 4 wire and earth then an external neutral is provided which the lamp can use.
5. On one of the specification plate images it says the machine is for 380V, but at the bottom right 'Voltage - 220V needs to be customized and pay extra...'
I think then that the original 380V 3 phase star motor has been 'customized' to run on 220V single phase. The ability to swap motor direction has been disconnected and all the rotary switch does now is switch on/off the L and N to the motor. What the black wires does at the rotary switch I do not know without seeing what happens where it is sleeved with white sleeving - is it attached to the metalwork to be the cpc? For China this would be the wrong colour for the cpc - they use green/yellow - black or blue are reserved for the neutral.
To operate at 220V the motor must be wired as delta. The 'customization' is to attach the black plastic box over the original motor terminal housing and place a capacitor to the left and right as shown. These capacitor are for start and run in the Steinmetz type 2(delta) circuit, where Cr and Cs are what you might expect ie:
What you see is a switch which introduces the start capacitor during run up and then disconnects it at operating speed. The grinder motor has no internal switch to do this and the rotary switch cannot be co-opted to do it. The customization overcomes the absence of the switch by wiring the motor as the red circuit drawn below which keeps Cs in circuit . The way winding W is fed via winding V reduces the potential across W to prevent it overheating when permanently fed via the low series reactance of Cs which although its value cannot be seen is normally of the order 200uF. By contrast the run capacitor is 25uF so a higher series reactance. Tracing out the machines current wiring one arrives at the circuit I point to in the middle of this scribbled diagram, where LN are across U:
I have not had time to think about whether the rotary switch can be used to provide REV- OFF-FWD control - perhaps others might think on this.
