DIYbanter - View Single Post - Crazy thought -- converting 480v drives to 240v

John

wrote:

On Sat, 06 Oct 2007 20:48:45 -0500, Ignoramus12852
wrote:

I am thinking about something. 480 VAC drives can be bought for next
to nothing. What they have is an inverter circuit and control
circuit.

They probably would not run on 240v because the internal transformer
that would supply voltage to the control circuit would supply only 1/2
voltage. They also might have an indervoltage sensor. I cannot think
of more things that depend on 480 volts being there.

So, if a hack could be done and a 1:2 transformer inserted between
480v inputs and the control circuit, then the drive would become a
240v drive with the same amp rating (and half HP).

What am I missing?

i

Not impossible but you would have to know a lot about the
detail design of the drive and be prepared for a lot of messing
about with the printed circuit board.

The output stage should be OK but,in addition providing the
correct supply voltages to the control and drive circuits, you
would also need to modify the output voltage regulator system and
protection circuits to enable them to make them compatible with
the lower output voltage.

An interesting project for the hardened experimenter with
adequate experience and test equipment but not a job to be
undertaken lightly!

Jim

The hardest part is to get a copy of the schematic of the drive so you
dont have to guess what is going on in it.

The phase rotation sensor and phase loss sensors would have to be
bypassed if you are running on single phase.

The current sensors would probably be ok since the high power
electronics ratings are already matched for the current setting of the
sensor. The voltage sensors would have to be modified for the lower
voltage on the DC buss.

The control circuits power supply would have to be modified to take the
lower ac input voltage unless is was a switching supply with a wide
range of input voltages.

the final thing is that higher powered drives are expensive, even the
480 volt ones since there is a continous demand for them. A new 40 hp
drive gets up in price.

John