Renovating a Hardinge HLV-H

[pauly45]

Hi Bill,

Thanks for such a prompt reply.

That makes a lot more sense now.
I'm assuming that the risk is that since only one phase is being used to supply all the output power, that it is the rectifier diodes on the one input that risk being over-loaded - all the output power being derived from one phase set of rectifier diodes rather than three ?

Do you just leave two of the input phases disconnected ?

Using a 3 phase 415 input VFD makes the selection choice much larger and cheaper !

Many Thanks - I'll look into 415v 3ph VFD's now !

Regards
Paul.

[BillTodd]

I'm assuming that the risk is that since only one phase is being used to supply all the output power, that it is the rectifier diodes on the one input that risk being over-loaded - all the output power being derived from one phase set of rectifier diodes rather than three ?

True, but since the rectifier diodes are usually integrated with the rest of the power devices, there's virtually no cost to the manufacturer to make the devices very robust (i.e. to use the same spec devices for the smallest and largest power VFD in a range).

The only real issue is ripple current heating in the capacitors.

Bill