Which power supply to use

I am setting up the power supplies for my setup and wanting to check that I get it right.
I'm looking at having 2 psu's one 48v for the stepper motors and a secondary for the vfd, uc400eth and possibly fans.
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I have a D100S1R5B Chinese vfd which is marked up with input as ac220v 50/60htz and 8 amp output; I also have a uc400eth that takes 5amps to power from either 12-24v psu.
I have the stepper motors linked up with a 48v 5amp psu and I have a 24 10amp spare which the vfd was originally with but confirmed burnt out cooler fan so needs a replacement.
What I would like to ask is what secondary psu is best suited for the vfd, uc400eth and possibly cooler fans as I don't know this side of things at all with power usage and don't want to fry anything.
I am looking at linking the two psu's to the same mains cable is this advisable? (Mains to 48v to 24v)
Or am I looking at this wrongly and that I can use just the 48v but with converters?

The UC400 doesn't need 5A supply. That is a misunderstanding. Also, why don't you build your own, at least for the steppers.

The VFD shouldn't need a separate power supply.

A 24VDC 2A DIN rail mount power supply should be more than adequate for the controller/controls, unless you're running anything that requires substantial current. However, if you've already got a larger current 24VDC supply, then use it. Extra current won't kill anything, unless you wire something up wrong.

For steppers, I'd always recommend a basic unregulated supply, but if you're 48V supply works, just stick with it.

Looking at the UC400ETH manual, and having examined my UC300ETH/5LPT closely, I'm going to suggest the following:-

Background info: The UC400ETH has a small DC-DC convertor to take the incoming supply and provide a regulated 5V for the output drivers (the smaller chips - 74HC14's). There's a secondary 3-pin linear regulator, likely 3.3V for the micro controller. The resistor networks (39k, 22k and 4k7s) are all geared up for adapting 5V signalling to the 3v3 levels for the micro controller. This design is common with the UC300ETH/5LPT.

Also, the manual does state that the incoming DC voltage should be between 12V 500mA, and 24V 250mA. This is pretty straightforward - and suggests that a 6W or 6VA supply is required for the UC400.

Summary of what you have:

You have a 48V PSU already for your stepper drivers. So we take that off the table.

You mention a supply "with" the VFD - which is 24V, 10A. You mention a cooler fan, that's burnt out?, it's unclear to me if this cooler fan is part of the VFD, PSU, or just within the enclosure? Please clarify - and what burnt it out? (there are not many failure modes for a fan - usually over voltage - which would make me want to verify the performance/operation of the supply before trying to re-use it).

The D100S1R5B is marked (from Aliexpress) as having a 220V single phase AC input (the marking of 8A output refers to the maximum drive current into the spindle motor) - so no PSU requirements for that, over than a direct 220V supply.

So, I think:-

You only need a supply for the UC400ETH, and any services (cooling fan, illumination, water cooling pumps etc?). The UC400ETH has onboard regulation which, given the requirements of the services that I mention, is unlikely to suffer significantly from any regulation or filtering issues, and I'd be cautiously satisfied that it could all run on a single supply. This then means you only have to determine the best, most appropriate voltage level for the services (for me, that's 12V, since I can then use PC-based water cooling kits, but it's horses for courses). Given this very basic requirement I'd budget (at 12V) for 500mA for the UC400ETH, similar for the fan, 800mA for the pump. So, 12V 2A would suit my needs and I'd be looking at something like http://cpc.farnell.com/mean-well/dr-...5?st=12V%20din (which, co-incidentally, I've just bought one of).

For preference, I'd keep the logic (the UC400) on a separate PSU to noisy things like fans and pumps - and therefore a separate PSU - but that's probably just me being cautious.


Regarding wiring the supply to this PSU in parallel with the supply to the VFD - why not?, even if you wired them separately back to two separate 13A plugs they'll still be effectively wired in parallel, but just in the building wiring rather than your enclosure. The exception to this rule is when you overload the incoming power capacity to the enclosure (for example, standard IEC connectors are only rated at 10A).

I thought the UC400 needed a power source as its got the + - connectors?

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Originally Posted by Palletlad

I thought the UC400 needed a power source as its got the + - connectors?

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Yes, it does. Any voltage, from 12V through 24V DC, according to the manual, and with a current rating between 500mA and 250mA (Multiply the voltage and the current to get the power requirement, e.g. 12 x 0.500 = 6Watts, or 24 x 0.250 = 6Watts : basically it needs 6 Watts of power).

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Originally Posted by Doddy

You mention a cooler fan, that's burnt out?, it's unclear to me if this cooler fan is part of the VFD, PSU, or just within the enclosure? Please clarify - and what burnt it out? (there are not many failure modes for a fan - usually over voltage - which would make me want to verify the performance/operation of the supply before trying to re-use it).

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Sorry I didn't make this clear I meant the fan inside the 24v PSU that came with my cnc machine stopped working and magic smoke appeared.

So am I right in thinking the VFD is safe to have wired up to the 48v 5amp 220 PSU Doddy with your explanation?

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Originally Posted by Palletlad

So am I right in thinking the VFD is safe to have wired up to the 48v 5amp 220 PSU Doddy with your explanation?

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The D100S1R5B VFD does not need any power supply, it is plugged into the wall socket and is a power supply to the spindle. The the motion electronics (driver, motion controller and such) plus the stepper needs DC power supplies. I don't know where you would connect the 48V to the VFD.

PalletLad: one of us is confusing the other: the VFD takes a mains supply.

You can wire the same mains feed to both the VFD and to the PSU but the PSU does not provide an electrical supply to the VFD

Sorry I got confused as the original setup they have daisy chained the VFD and PSU to the same wires so for a novice like me it looked like the power went through the psu first then the vfd.

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Originally Posted by Palletlad

Sorry I got confused as the original setup they have daisy chained the VFD and PSU to the same wires so for a novice like me it looked like the power went through the psu first then the vfd.

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What do you mean by daisy chained? The VFD and the PSU must be connected in parallel on the mains side.

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Originally Posted by A_Camera

What do you mean by daisy chained? The VFD and the PSU must be connected in parallel on the mains side.

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The term "daisy chain" can be applied to parallel-connected devices.

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Originally Posted by Doddy

The term "daisy chain" can be applied to parallel-connected devices.

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Yes I know, but considering he sounds confused regarding electrical connections and what is what, it is not clear what he means by "daisy chained" and which end is connected where.

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Originally Posted by Palletlad

Sorry I got confused as the original setup they have daisy chained the VFD and PSU to the same wires so for a novice like me it looked like the power went through the psu first then the vfd.

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Erm.!! . . . Are you sure what your calling VFD is actually a VFD.?

To be honest from the looks of the questions your asking it's clear your level of electrical knowledge is very low so maybe you should back off a little and maybe seek help from someone who has more knowledge. Because when comes to PSU and VFD's your dealing with mains voltage which WILL KILL YOU without asking if you know what your doing.!

I'm strongly advising you to ask your self if your capable. I'd also strongly suggest you don't turn anything on untill your 100% sure know it's correct or get it checked by someone who does.
We can help you but only to a point and if you don't understand the basics then it's very easy to blow expensive things up or god forbid much worse.!!

Thank you for the concern I don't deny I know nothing in regards to electrics, I have now sat down and had a lengthly chat with a trained technician (took your advice) and went through a lot of questions about wiring and power usage whilst going through the wiring with a dvm.
My "daisy chain" term I used was actually a "series" connection.
And I was shown that the vfd is connected to the live and neutral connectors on the psu so was getting a DC from the mains and not through the psu.
What I will do is draw up a diagram of my wiring and get it double checked.

Hi Palletlad.
I think you should talk again to your electrician friend as you seem to have a problem with understanding the difference with ac and dc power conections. As Jazz said this could kill you. Be carefull. Cheers Andrew

just seen my mistake...

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Originally Posted by Palletlad

Thank you for the concern I don't deny I know nothing in regards to electrics, I have now sat down and had a lengthly chat with a trained technician (took your advice) and went through a lot of questions about wiring and power usage whilst going through the wiring with a dvm.
My "daisy chain" term I used was actually a "series" connection.
And I was shown that the vfd is connected to the live and neutral connectors on the psu so was getting a DC from the mains and not through the psu.
What I will do is draw up a diagram of my wiring and get it double checked.

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This post is even more confusing than the ones before, and just as I suspected, your use of the term "daisy chain" is wrong. Do you actually know what the difference is between parallel, serial and daisy chain connection? I am with Jazz... contact a trained electrician and ask him/her to connect at least the mains and the VFD - spindle cables, and of course the earth. Those cables can literally kill you, or anyone touching your machine, if you make a small mistake. Discussing this with a technician friend (technician in which field...?) is pointless and can be even more dangerous unless you actually KNOW that he/she knows the subject AND you understand what he/she is saying.

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Originally Posted by Palletlad

just seen my mistake...

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A picture or a sketch wiring diagram would paint a thousand words:uncomfortableness:

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Originally Posted by A_Camera

This post is even more confusing than the ones before, and just as I suspected, your use of the term "daisy chain" is wrong. Do you actually know what the difference is between parallel, serial and daisy chain connection?

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To some, this comment may seem little condescending coming from a bunch of electrical geeks just trying to show off.!! However, A_Camera is making a very valid point because Terminology is very important in some cases. When dealing with low voltage low current devices then getting the wording wrong is at worst just expensive. But when taking mains voltages/currents it can become lethal to anyone who touches the machine.

Trying to help builders who have little or NO understanding of electrical terms via Forum post's is inherently dangerous. There are too many contributors that jump in and confuse matters to the point can become dangerous for the OP.
Me personaly I won't get into these forum posts other than to advise if something is very wrong or I see an obvious mistake. However I don't mind helping people on a 1 to 1 basis either via PM or Email so there are no outside influences to confuse.

So in this case I'm offering to help but off air so to speak or suggest that you seek help from another Forum member or friend who KNOWS what there doing.