I have a 460v 3 ph. 3 hp. Allen Bradley VFD. I would like to apply DC
to the buss from a single phase power supply instead of a rotary
converter. Any problems with this?

wrote:
I have a 460v 3 ph. 3 hp. Allen Bradley VFD. I would like to apply DC
to the buss from a single phase power supply instead of a rotary
converter. Any problems with this?

Most of these smaller VFDs will run off DC. The problem is you need to
supply 680 V DC to it. It may be a lot easier to supply it with
single-phase 480 V by using a step-down transformer backwards, and using
the internal rectifier, etc. Unless you will run the motor at full
rated load for extended periods, it will probably work fine. I have a 1
Hp 230 V VFD on my Bridgeport mill with 1 Hp motor. The VFD is rated
for 3-phase input only, but it has run fine for years.

Jon

On Dec 27, 12:27*am, "
wrote:
I have a 460v 3 ph. 3 hp. Allen Bradley VFD. I would like to apply DC
to the buss from a single phase power supply instead of a rotary
converter. Any problems with this?

Maybe you can run the DC bus from an external source, but the control
electronics do not run from the DC bus, they need the AC input to some
transformer for (possibly?) 5 volts, and whatever other voltages are
used to for the logic, and transistor drives.

IOW, I think you ~might~ be able to give it the high voltage 680 volts
DC power, but you might also have to give it the 480 volts AC to drive
the computer and transistor drive/control circuitry.

Half-Nutz wrote:
On Dec 27, 12:27 am, "
wrote:

I have a 460v 3 ph. 3 hp. Allen Bradley VFD. I would like to apply DC
to the buss from a single phase power supply instead of a rotary
converter. Any problems with this?


Maybe you can run the DC bus from an external source, but the control
electronics do not run from the DC bus, they need the AC input to some
transformer for (possibly?) 5 volts, and whatever other voltages are
used to for the logic, and transistor drives.
Nope, most of the smaller VFDs use a little DC-DC power supply
that runs off the main rectifier. You can usually tell these
because, when idling and you cut off the mains supply, they
continue to "run", ie. the panel display stays active for many
seconds, then you get an undervoltage display, then it finally
powers down some 15+ seconds after power is removed.

Jon