Wiring Acorn Power Unit For 230V UK Power Supply

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ChrisMe
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Wiring Acorn Power Unit For 230V UK Power Supply

Post by ChrisMe »

Finally got my Acorn board delivered to the UK and I was wondering if someone can direct me to the wiring document showing how to connect the power supply unit to be used with a 230V UK power supply? Also, when I attach a plug to it should I use an 11A or 13A fuse? Thanks.
Richards
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Re: Wiring Acorn Power Unit For 230V UK Power Supply

Post by Richards »

I highly recommend that you ask an electrician to help you get things wired up properly.

Please don't depend on me or others on the forum to give you absolutely accurate information. The electrical code in my area may be completely different from the electrical code in your area. That being said, I found a web site (https://job-prices.co.uk/wiring-colours/) that shows the wire colors used in the UK. Until 2006, RED was Live, BLACK was NEUTRAL and GREEN/YELLOW (or just bare wire) was GROUND. Since 2006, BROWN is LIVE, BLUE is NEUTRAL and GREEN/YELLOW is GROUND.

In the USA, using single phase 120VAC, BLACK is LIVE, WHITE is NEUTRAL and GREEN is GROUND.

The Meanwell RD-35B power supply that came with each of my Acorns came with a power cord prewired to the power supply. The RD-35B accepts voltage ranging from 100VAC to 240VAC. No voltage selector switch is used. The RD-35B has a label showing that its input is rated for 0.8A at 115V and 0.55A at 230VAC. Its outputs are rated at 2.2A for 5VDC and 1A for 24VDC. Any fuses used should be at or below those current ratings.

The RD-35B is meant to supply power to the Acorn only. Page 8 of the Acorn User Guide shows that the Acorn's minimum 24VDC current requirement is 0.5A, so the RD-35B can easily handle that load.

I'm not sure where you got information about 11A or 13A fuses. That's more current than I allow for my entire enclosure. Because I normally use small steppers or small servos, I normally wire my enclosure's power cables with 16 gauge wire (rated to handle 10A up to 6 feet). That means that the maximum main fuse I can use is 10A at 115VAC. If I used 14 gauge wire, I could use a 15A main fuse. If I used 12 gauge wire, I could use a 20A main fuse. The wire gauge going to the main fuse and exiting the main fuse must be a gauge sufficient to handle the current allowed by the fuse. In my case, I use 16 gauge wire going to and from the main fuse. That same gauge wire is used going TO the Meanwell MDR-60-24 or MDR-100-24 power supply that I use. For simplicity, I use 16 gauge wire from the auxiliary fuse to the MDR-xx-24VDC power supply. I use 18 or 20 gauge wire exiting the power supply. The maximum current of the MDR-100-24VDC power supply is 4A. Twenty gauge wire is rated to handle 11A for chassis wiring.
-Mike Richards
ChrisMe
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Re: Wiring Acorn Power Unit For 230V UK Power Supply

Post by ChrisMe »

So if I attach a UK plug to the power cord the power unit will automaticly work? I don't need to change the conectors at the back of the unit?
martyscncgarage
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Re: Wiring Acorn Power Unit For 230V UK Power Supply

Post by martyscncgarage »

ChrisMe wrote: Tue May 04, 2021 8:40 am So if I attach a UK plug to the power cord the power unit will automaticly work? I don't need to change the conectors at the back of the unit?
The power supply that comes with Acorn is an international unit. It auto detects whether it is on 120 or 240V. Verify the label, but that's been the case for quite awhile. Yes, cut off the US cord end and PROPERLY wire your cord cap. If you are unsure, as Mike Richards suggested, get some help from an electrical professional.
Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
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ChrisMe
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Re: Wiring Acorn Power Unit For 230V UK Power Supply

Post by ChrisMe »

martyscncgarage wrote: Tue May 04, 2021 10:06 am
The power supply that comes with Acorn is an international unit. It auto detects whether it is on 120 or 240V. Verify the label, but that's been the case for quite awhile. Yes, cut off the US cord end and PROPERLY wire your cord cap. If you are unsure, as Mike Richards suggested, get some help from an electrical professional.
Marty
Thanks. I know a really good electrical guy but he is on Holiday until Monday. I'm just really eager to get using the CNC 12 software.
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Re: Wiring Acorn Power Unit For 230V UK Power Supply

Post by Muzzer »

I have to honest and say I've never heard of an 11A fuse here in the UK - std sizes are 1, 2, 3, 5, 10 and 13A. Of course, we are unusual in having fuses fitted within our mains plugs. Most countries including the US simply rely on circuit breakers within the consumer unit. There again, they don't use our "ring main" arrangement.

You should always fit the smallest fuse that will meet the input current requirement. The PSU supplied appears to be an RD-35B which has an input current of 0.55A, so even a 1, 2 or 3A fuse would be fine. https://www.meanwell.com/Upload/PDF/RD- ... -SPEC.PDF

These PSUs are "universal input", so they will operate correctly when supplied with any voltage between 88Vac and 264Vac.

Sounds as if you'd be advised to get someone to help you to wire up the PSU. Having said that, they are designed to be fitted within enclosures, so you could still accidentally touch live connections if you don't take care.
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