800w spindle - noise & controlling remotely

[Jonathan]

Just the base frequency setting isn't what you need, as that's the voltage at the rated frequency (400Hz), but we need to know the voltage across the whole range. Have you checked that the frequency this voltage refers to is definately 400Hz, as if it's 50Hz that would explain what's causing the problem, as it means the VFD is applying 8 times the required voltage at 50Hz.

You're correct in saying that a DC output of 230V would imply a very high current (although it's not 230V DC, 84V or even 28A), but fortunately the VFD outputs AC not DC! The impedance of the spindle increases with the frequency applied. You can think of impedance as resistance, but for an AC circuit with inductors/capacitors. So at 0Hz (DC) the impedance is equal to the DC resistance you measured (3 ohms, which sounds about right), but as soon as you increase the frequency the impedance increases proportionately. It also changes with load. That's why as the frequency increases you need to apply a higher voltage to be able to output the same torque. So in short your measurement implies that the winding's aren't burn out, but it's nowhere near enough to say if the spindle will work.

Alas, the menu structure, naming convention (& indeed the manual itself), is anything but intuitive!

Strangely the translated chinese manual for the VFDs most people get to control their spindles are easy to understand.

Have you got skype? If you're sitting there with the VFD we can probably sort this out in half an hour...