Wiring Diagram check

[Nr1madman]

looking at diagram in post 42 I have noticed two issues-

I would expect wiring in series a 12V fan & 12V pump across a 24V supply will damage the fan !
( pump will look like a short circuit so most of the 24V will be across the fan )

connecting a diode (FR607 ?) across each stepper driver supply fuse
will provide a path for the back EMF from the stepper motor
when a fuse blows

see revised diagram


John

About the diodes across the fuses for stepper drivers..
How big of a problem is it if you don't use a diod?

In my mind it's more probable that the fuse will break during acceleration instead of deceleration?

I might be wrong? :)

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[cropwell]

I think that the driver output stages have back emf protection, as the first vulnerable components are the switching transistors. I have been unable to find a circuit for that driver, but they are all much of a muchness. A diode across the fuses is belt and braces.

I totally agree about the pump and fan.

[Neale]

Why bother with the diode at all? Just another complication. The driver itself has overcurrent protection so if there is a wiring or motor fault, the driver should turn off and raise a fault signal. So all the fuse is doing is protecting the wiring if there is an internal fault in the driver. The fuse does not protect the driver - the fuse blows after the driver has already failed. So, thinking this through, the fuse will blow because of a driver fault, so you don't need to protect this driver any more, and the blown fuse will isolate that driver from the PSU and other drivers as well - if the PSU fuse hasn't blown as well.

I just have a single fuse in the PSU feeding all the drivers, rated at the nominal capacity of the PSU. Anyway, will the back EMF on a fault be any higher than the back EMF in normal use while decelerating?