Wiring Diagram check

[eurikain]

Hello nairepooc,

First off, let me apologies for not posting earlier. I have been very busy these past few weeks, but I finally found some time to take those pictures you asked for. I hope these will be helpful to you. If you need more pictures, let me know. My camera turned on the flash for every picture, if you want I can try to take new ones without the flash, they might turn out a little brighter.

All the best, G.

[Tom J]

I think you mean the 'star ground'. This means all grounds from shields etc. all meet at one point, and this one point is then connected to the ground from your mains cable.

I'm not an electronics whizz but I think the idea is to avoid 'ground loops'.

Here is one of my older diagrams (a few changes since) - see the yellow cables which all join at a single point. This is then connected to the mains cable earth.
Attachment 17266

Here is a picture of my control cabinet - ground is yellow and green. You can see that all of these cables meet up at a group of terminal blocks that are right next to each other (this is my star ground point). Because they are special earth terminal blocks they also connect to the metal DIN rail underneath which effectively joins them all together at that point. The middle terminal block then has a single wire which goes back out to the mains earth.

Attachment 17265

Note that my VFD is completely separate (separate mains cable, shielding and earthing), but many people run everything off one socket.

What kind of transformer is used in your 68V PSU? Asking as you use MCB is tybe D which would be ok for torus trafo.

[Clive S]

What kind of transformer is used in your 68V PSU? Asking as you use MCB is tybe D which would be ok for torus trafo.

It will be a toroidal transformer 25-25v AC in series or 50-50 in parallel MCB D type

[routercnc]

Hi Tom,

I used 750VA, 2x24v in series (close Clive, I know some use 2x25v but I think it tipped the voltage a bit high once rectified and smoothed etc. ? Can't remember. I get 72V unloaded so OK with that.)

Toroid from Airlink transformers:
http://www.airlinktransformers.com/

Read post #42 onwards for the Toroid/PSU development, and read post #70 for the 'final' wiring diagram. . .
http://www.mycncuk.com/threads/6988-routercnc_MK3/page5

Note that I went with the 10A Type D MCB in the end as the 6A tripped out on startup due to the inrush current (no soft start). It's been running fine since.

Thanks

[Tom J]

Hi Tom,

I used 750VA, 2x24v in series (close Clive, I know some use 2x25v but I think it tipped the voltage a bit high once rectified and smoothed etc. ? Can't remember. I get 72V unloaded so OK with that.)

Note that I went with the 10A Type D MCB in the end as the 6A tripped out on startup due to the inrush current (no soft start). It's been running fine since.

Thanks

I have both 720VA 2x30V 2x12A and 420VA 2x30 2x7A in two different application. All secondary winding have to be in phase (start 1st coil & start 2nd coil as one cable and end 1st coil with end 2nd as one cable)
I tried 4A type D MCB and was tripping out from time to time on 720VA - did not try bigger MCB, will do try on smaller 420VA.
I might get away from using soft start

[Tom J]

I have both 720VA 2x30V 2x12A and 420VA 2x30 2x7A in two different application. All secondary winding have to be in phase (start 1st coil & start 2nd coil as one cable and end 1st coil with end 2nd as one cable)
I tried 4A type D MCB and was tripping out from time to time on 720VA - did not try bigger MCB, will do try on smaller 420VA.
I might get away from using soft start

Got recently 2x45V AC 500VA nad was tripping 4A type D MCB as well, will update with 6A or 10A type D when they arrive.

[Nr1madman]

Thanks for an exelent thread!
Will be stealing much from the latest schematic for my own build.
Just have a question :)

Why is the enable signal wired in a relay that's controlled by the master relay?
Why not just use the master relay and skip one relay?

Thanks
Robert

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[john swift]

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

[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.