Spindle wiring

Unfortunately one of the issues of having purchased a 2nd hand machine that you haven't seen working and has been modified is not knowing why the modifications were done. At this point I'm trying to work out the wiring of the spindle to the VFD. The VFD is a HY01D523B and the spindle is a GDZ-65-800. The spindle has a 4 pin connector on it but the cable from the VFD looks to have been modified with only 3 wires coming out of it and wrapped around a ferrite choke. I'm not sure if that's all this spindle needs to run, but having never used these spindles and VFDs before I don't want to experiment by plugging it in as is without checking over everything first. I've got the checklist of settings for the VFD from another post so the wiring is all that is holding me up from powering it up.

Hey Justin,

As far as I have read on these forums, and in my own experience, generally Chinese spindles don't come with an earth connection wire despite having a 4 pin connector. If you open the rear of the motor at the connector end, you will likely find only 3 wires that are part of the motor windings which means there is no ground wire. Without a ground wire, there could potentially be some voltage applied to the metal casing of the motor if something internal to the motor weren't quite right ie. poor or damaged insulation, which could possibly give you some form of electric shock if you touched the casing. I would recommend adding a grounding wire of appropriate gauge to the 4th pin on inside of the connector and connect it to one of the internal screws of the motor which typically holds a plastic cap in place to cover the spindle bearings (if you would like a picture let me know). Then you can use a 4 core cable between the spindle and the VFD, with the 4th wire being connected to a ground on the VFD (which hopefully is also connected in some manner to your mains ground). Once this is in place, check that it is continuous with a multimeter. This is not critical to operation of the spindle, but important for safety. All commercial appliances that have a conductive metal casing will have some form of grounding connected to the casing for personnel safety.

Here is some discussion:
The Shapeoko Forum ? View topic - Chinese Watercooled 1.5kw Spindle
The 2.2Kw Chinese Spindles - Info, Setup and Advice + More

Suggested safety reading:
http://www.allaboutcircuits.com/vol_1/chpt_3/8.html

It is recommended that this is all handled by a certified electrician.