spindle with compressed air release collet

[GEOFFREY]

Is the spindle motor 3 wire (3 phase) or 2 wire (DC) ? I'm not convinced it's an inverter you need.

Thanks for replying Eddy. This is a 3 phase hf spindle and the original inverter is a 250hz - 1khz unit that gives a low voltage (15-60v) high frequency 3 phase output from a 240v single phase input. Speed control is via 0-10v analogue signal from the controller. I am aware that this is unusual, hence my difficulties and thoughts of getting the spindle rewound. G.