[BertZ]

Yes, I'm not new to this I repair VFD Drives, V/F control normally works best for these 400Hz Spindles most VFD Drives that have Vector Control, do not support 400Hz some will work up to 300Hz though some of the more expensive VFD Drives work well using Vector Control for the 400Hz 800Hz spindles

It's very easy to change the V/F Torque Curves first you have to have it run to see if it needs to be changed most don't,

Correct Grounding will not change much, but is a requirement, for any install like this, it also depends how much rotor voltage there is also as this has to go to Ground, if this is high in your spindle then it will cause a high current Fault

Fues and not normally used a Breaker is superior, if one of your Fues blow when you spindle is at full speed you will damage the VFD Drive and sometimes the Spindle this is why Fuses are not used

You should get the cheaper VFD Drive like the Huanyang this will work well with your spindle and not cost very much, high cost VFD Drives are not much better than some of the cheaper VFD Drives, it's your choice

It's quite clear in the manual how to wire your VFD Drive, Note your regular Fuse is not a Disconnect, which is a normal requirement for any install like this

Molded-case circuit breaker (MCCB) or fused disconnect:
? A molded-case circuit breaker or fused disconnect must be installed
between the AC source and the inverter that conforms to the rated
voltage and current of the inverter to control the power and protect the
inverter.

Just remember the Parameters must be set correct before applying Power to these Spindles or you will damage the VFD Drive or the Spindle sometimes both can be Damaged

After a couple of phone discussions with the factory I learned that this VFD has 6 fixed V/F curves (three for 50 Hz and three for 60 Hz) The seventh curve is user configurable for 400 Hz. But in order for this to happen, parameter 01-00 must be set to 7. Now I am able to input the V/F curve parameters that you recommended. But alas! The motors are still drawing too much bloody current!

Parameter 02-00 sets the no-load motor current threshhold. It is currently set at 1 amp. I will increase this in increments up to 4 amps and see what happens.

I am so close to pulling the trigger on a Vevor VFD at 1/4 the price; I just need to get my money back for the white elephant sitting in my electrical cabinet.