routercnc_MK3

[routercnc]

Did a bit more today.


Top left space is for 12V SMPS and VFD


I decided to use the DIN rail as the star earth point (instead of a small block I had in the corner of the cabinet) and am now using proper DIN earth terminals to connect up all the earths.


I've also added a lower DIN rail which is for DC, leaving the upper for mostly AC. I've also split out the main PSU positive into 3 feeds which will run down to the fuses on the new lower DIN rail and then into the drivers.
The old DC terminal blocks for 12V, 0V, and 12V 'switched' are gone and have been replaced by DIN rail terminal blocks (blue). I looked at all sorts of options here and went with these in the end. This type are actually meant for AC neutral so will be labelled clearly as 12V DC, 0V DC, and 12V switched.
The master relay and spindle inhibit relay are now on the DC DIN rail next to them.


The drivers have been moved down a bit and the trunking run around them. The BOB has plenty of space in case it starts mis-behaving and needs to be replaced.


The power supply has been wired up correctly (!) - still need to split out the black 0V cable into 3 feeds and tidy up the general wiring but otherwise PSU is nearly done. As reported previously it all works.


More terminal blocks are on order! All for now . . .

[GEOFFREY]

That looks very neat and professional. Well done. G.

[routercnc]

Thanks Geoffrey,

Starting to enjoy the electronics but would really like to finish it soon !

Can anyone confirm that using an SSR (25A) is OK to control the 2 power supplys? My plan is to apply 12V DC across the DC side and switch the 240V AC supply of the live cable to the 72V linear power supply primary, and also to the live cable of the 32V SMPS.


I understand that when SSRs are 'off' there is still a small voltage which passes through the AC side so in theory the drivers are still powered, although the voltage is very small. Is this the case and should I be concerned about it? Should I add anything else?

I also understand that an SSR works well with pure resistive loads - but I think the linear supply is a heavily inductive load with voltage and current out of phase. Is this the case and again is it a problem for these SSR devices?

I don't know what type of load the SMPS is but again will this switch well with the SSR?

See post #62 for the circuit diagram - the SSR is slightly right of centre.

This is a sketch of where it will be located (red rectangle):


Thanks for your help

[routercnc]

OK, I've added the 25A SSR but am not sure it is the right device to use to switch the linear supply. Here's why . . .

The SSR is connected to the e-stop circuit to cut or supply power to the driver power suppliers. To test it out I tried it on the driver supplies one at a time. When I just connected it to the SMPS (30V) it all worked fine (on the one time I tried it). But when I connected it to the linear power supply (750VA coil, 40,000uF caps, 72V output) the MCB tripped (6A type D). Previously on the couple of times I tried it without the SSR it did not trip.

I'm now convinced that the SSR is not the right switching device for linear supplies due to the high inductance of the load, but I'd welcome a second opinion. I've been hesitating using a contactor because they all seem to be 24V and my box runs 12V. But I now think it is the only way so I'll have to modify all the 12V items to work with 24V. I did look at 12V to 24V DC-DC convertors but didn't like the idea of running it for extended periods to hold the contactor closed. Plus, I think they give out electrical noise?

So to convert the box to 24V needs a resistor for the 12V LED, and either resistors for the mechanical relays, or most likely swap them out for 24V versions. The pump and lights are 12V each so I can add them in series and switch both at once (instead of independently).

So the big question is what current rating of contactor do I need to switch the big linear supply (X,A,Y axes) and the SMPS (Z axis)? I'm guessing many tens of amps at least? The inrush current on this linear supply is quite high I suspect but the online calculations for current spec seem very involved. Does anyone have an idea of what to use? I don't want to run it for a bit then burn it out.

Thanks

[njhussey]

I think I've got this one...http://chaloncomponents.co.uk/epages...ucts/NC1-1210Z but without looking at either it of the paperwork I can't be 100%. My PSU is a 625VA unit and also going through it is the 230V Nema 34 driver and 24V PSU.

I'm sure someone far more electrickery minded will pop along soon!

[routercnc]

Hi Neil

Thanks for that. Google search shows this is 12A which I think would be ok for continuous running just not sure about the inrush. Is yours powered up yet and running everything connected to it without problems? Thanks

[njhussey]

Unfortunately mine's had nothing done on it in the last 2 and a bit weeks as one of my colleagues (there's only 3 of us in the office) is on long term sick so I'm now doing all the design and engineering as well as all the other stuff I normally do so this has taken a backseat

I got the 12A one as I was going to put a soft start on my torroid....not got round to that yet. I'll probably do it if I have problems.....