Re: 24VDC POWER SUPPLY

--- In CAD_CAM_EDM_DRO@y..., "ers2001ckk" <chan@p...> wrote:

> I have many surplus switching power supply adaptor
> output at 24VDC 2amp. I connect 2 pcs in parallel
> with diod in5 at the positive end supply to the GECKO 320
> running a DC motor at 3.5 amp using Turbocnc and run it
> for many hours. The end results is 1 is hotter than the other
> the output measured 2 amp. Funny 2+2= 4, howcome 2+2=2
> Any power supply experts out there can advice me.

Two regulated power supplies in parallel will not "load balance"
(supply the same amount of current) unless the voltages are VERY
close. One will almost always supply the bulk of the current even if
it is only a few tenths of a volt higher in output (the other power
supply reads the output voltage and never supplies anything) The
diodes serve to help isolate the two outputs but current will flow
from the highest source. True load balanced supplies have one supply
that is the master and the other tracks it and tries to match the
output exactly. If you put two batteries in parallel, current will
flow from the one with the higher voltage until it reaches the level
of the lower cell. They do not supply current in the same ratio as
their voltages.

You could put a current meter on one of the supplies and trim its
voltage (if the supply has an adjustment) until the current is close
to being balanced. You may have to play with each one to get a
balance. Twin meters would help but then you have $$$ tied up in
meters!

Most of the time when you use two supplies in parallel then each one
is rated for the full load and they act as "hot spares" (backup) in
case you loose one. Often used in critical equipment that is not
tolerant of power outages.