[Mr Sprue]

Probably nothing to worry about, but seeing I am no electronics engineer I would like to know if my PSU arrangement could encounter any complications, especially heat!

The aim is to keep the 240V AC and 12V DC power away from the low volt signal control wires, the Planet CNC PCB's will be mounted in the opposite corner at the back of the cabinet.

The 240V ac supply has an IEC C14 socket with a EMI filter incorporated into it.

Many thanks
Dave


Attachment 513630


Attachment 513632

[CNCMAN172]

Your layout will work fine. Just keep the AC power lines away from all low voltage signals

[peteeng]

Hi Dave - Are you going to drive the motors with 12V? The DM556 are rated at 48V usually and I recommend you drive motors at the highest voltage possible. 36V or 48V would be best. I have made a 12V system and it moved poorly. The higher the drive voltage the better. I don't use under 48V now. Built 24V and 36V systems as well. The higher voltage runs smoother. Your layout is fine. Peter

[Mr Sprue]

Your layout will work fine. Just keep the AC power lines away from all low voltage signals

Thank you for your reply.

The only low voltage wires that will be in the same conduit as the 240 AC, will be the 12V PSU output lines to the control boards, that should be okay will it not?

Cheers
Dave

[Mr Sprue]

Hi Dave - Are you going to drive the motors with 12V? The DM556 are rated at 48V usually and I recommend you drive motors at the highest voltage possible. 36V or 48V would be best. I have made a 12V system and it moved poorly. The higher the drive voltage the better. I don't use under 48V now. Built 24V and 36V systems as well. The higher voltage runs smoother. Your layout is fine. Peter

Hi Peter

The small PSU's are for the Main and OptoCtrl control boards.The vertical LRS-200 is 36V, and is the one I intend to use for the stepper drivers.

Cheers
Dave

[CNCMAN172]

Thank you for your reply.

The only low voltage wires that will be in the same conduit as the 240 AC, will be the 12V PSU output lines to the control boards, that should be okay will it not?

Cheers
Dave

What? You are using 240VAC and putting 12VDC power lines in the same conduit? Not a good idea. The DC power supply output lines will not cause any noise on low voltage lines, the DC output lines can run in conduit with other LOW VOLTAGE lines but NO AC lines, doing so will create a noisy mess and they system will have constant issues, trust me.

[Mr Sprue]

What? You are using 240VAC and putting 12VDC power lines in the same conduit? Not a good idea. The DC power supply output lines will not cause any noise on low voltage lines, the DC output lines can run in conduit with other LOW VOLTAGE lines but NO AC lines, doing so will create a noisy mess and they system will have constant issues, trust me.

So you are saying that the 240VAC power supply to the PSU's must be separate from their 12VDC outputs? So what about the PSU connections? Because I have the small PSU units orientated on their sides, the 240VAC wires will be connected at the top, if I have to re route the 12VDC away from the 240VAC these wires will cross over at the PSU connecters. So will that cause any issues?

[peteeng]

Hi Dave - I don't think the 240V 50htz will cause issues with the low voltage DC even if they are side by side. Thats been my experience on a few machines. Pay attention to grounding everything correctly. The main issue is the high frequency spindle voltage. This line needs to be in a shielded cable and earthed correctly and preferably filtered. Peter

[Mr Sprue]

Hi Dave - I don't think the 240V 50htz will cause issues with the low voltage DC even if they are side by side. Thats been my experience on a few machines. Pay attention to grounding everything correctly. The main issue is the high frequency spindle voltage. This line needs to be in a shielded cable and earthed correctly and preferably filtered. Peter

Hi Peter

Many thanks for your reply, the subject on CNC electronics is certainly a mine field isn't it?

Yes for VFD which also is a 3 Phase inverter, I purchased a few metres of 18 AWG four core tinned shielded cable a while back, after receiving some good advice from the tech support at Inverter Drive Supermarket here in the UK. In addition to this I have also purchased some Velcro Shielded Cable Sleeve from Ali Express, should I need additional protection.

One thing that I did find out though, was the that the shield from the cable has to be earthed at one end for signal cables, but for VFD cables grounding at both ends may be necessary. The VFD cable will only be about a metre long so I'll probably just earth at one end.

Cheers
Dave

,

[peteeng]

Hi Dave - Yes, the electronics has been a long journey. I'm a mechanical engineer and the mechanical side even has had a few hiccups. One thing that comes to mind is the brake used on the Z axis screw to stop the z axis from falling when there is no power. On two early machines I just had the brake connected to the 24V PS output and it worked fine. On a machine I sold 2 years ago it always fell and we thought it was the brake lagging, then the switchmode power supply lagging and we tried various relays and transformers and bits and bobs over time. Then I decided to pull my machine down and understand why it worked. Seems the latest screws I get have much less friction than the ones I was buying years ago and so the newer machines fall. So I used a "delay on" switch/relay, on the brake so the brake release and the PS power up overlapped by 0.5sec and all's well. So good luck on the build and any Q's will be answered by the forum. It's all been done before somewhere here. Peter

[Mr Sprue]

@peteeng

Hi Peter

Thanks again for your support, I'm a tool maker and the machine I'm retrofitting is an Emco, so I have a lot of expectations for this quality Austrian built machine.

One thing though that is a head scratcher, alongside with limit switches it has Honeywell proximity sensors fitted to to it. Damned if I have found anyone yet that can explain why Emco fitted these!

[peteeng]

Hi Dave -Which EMCO? always interested in mill conversions and Mill builds. My next build will be a small mill been looking at concrete, epoxy granite and various things but steel and aluminium seem to win. My guess on switches is that one set will be used for end of travel (proximity), the other set for homing (mechanical?). It is possible to use one set for both but some choose to separate the functions. Regards Peter

[Mr Sprue]

Hi Peter

Its an Emco PC 50 with a three phase AC spindle motor. Initially I almost didn't buy it because of its huge footprint, which made the machine overhang the workbench by nearly a foot! But after removing the huge red (18kg) control cabinet, and making a few alterations it now only overlaps about four inches. Below are images of what I have done so far, I've had the machine colour matched, so will spray paint the panel work when I've completed the electronics and have the machine running. If you buy one these machines I have the sheet metal drawings that I created in CAD.


Attachment 513684

Attachment 513686

Attachment 513688

[JaceFleming]

Consider proper insulation and airflow to prevent overheating and signal interference.

[weouter]

its always a good idea to keep the main voltage away from data wires, it can happen that if it isn't shielded it corrupts the data going trough.