Q for Mariss (was Re: Here's my proposed power supply setup.)

Hi Ralph,

suffering a recent blowout of a controller, I wish I had taken the
time to put in an automobile brake light.

one puts the 470uF cap on the Gecko power input, and the fuse as you
mention, but then also adds an autombile light as another protection
device.

if something went wrong, the light would light as the current was too
high. this would bring the voltage down at the same time.

if everything was right then the light would just let the electricty
flow normally.

Dave

--- In CAD_CAM_EDM_DRO@y..., "rawen2" <rawen2@y...> wrote:
> Hi Mariss,
>
> I'm currently building my 4 axis power supply and would prefer to
do
> it right the first time.
> I'm assuming fuses or circuit breakers are placed between the power
> supply main filter capacitor and each individual motor driver as
> Lloyd mentioned in his setup.
> A while back there was a discussion about disconnecting motors
while
> powered up and the back EMF generated by the collapsing magnetic
> field in the motor would damage the driver. So what happens when a
> fuse blows on the driver's supply side?
> Do you have any general guidelines for placement and sizing of
fuses
> or CB's in our stepper power supplies? What if the main capacitor
> breaks down and shorts? Should the primary or secondary sides of
the
> transformer have fuse or CB protection that would kick in before my
> garage's 20A CB does?
>
> X,Y,Z steppers are 3.5 V 5A 650oz/in. No 4th axis yet.
> Transformer is 700VA Plitron toroid 50VAC @14A output. Should be
> around 70VDC after bridge.
> Bridge rectifier is 25A 600PIV.
> Surplus capacitor is rated 56,000uF 80VDC. Kinda big I guess after
> seeing your calc but the higher voltage ones are harder to find and
> the price was right.
> Drivers are APC CMD260's (Sorry, got 'em cheap)
>
> Thanks,
> Ralph Wenzl