# How can I power an Arduino in a 3-phase environment?

I am working on a project which uses an Arduino board. Currently I am testing my device using 2-phase power and it works fine. I want to use that device in agriculture fields where 3-phase power is available instead. How can I do this?

• Typically low wattage accessory equipment in 3-phase systems is supplied by just two of the three wire phases, but you will need a power supply rated for the unusual voltage which results. Nov 29, 2015 at 16:33
• You do not want to connect your arduino to mains voltage, do you? So your question is probably about the powers supply you are using. As there is no arduino branded PSU you will have to give us more information about that PSU and your local mains voltages. Otherwise it will be deleted. Nov 29, 2015 at 17:43

The very short answer is that the Arduino board itself is designed to be powered by low-voltage DC (but you almost certainly already know this). So what you're really asking, I think, is "can you use the mains power supply that converts mains AC to DC on a three-phase supply?"

The answer to that is a guarded yes. You will need to confirm that you are connecting to a single phase (basically what you were doing in testing) and that the voltage is appropriate for your power adapter.

The abridged version of the gory details follows…

Three-phase supplies are almost always used for motor or other power applications – for a low power device like an Arduino (or even lighting or small appliances) you don't typically need three-phase. What is usually done is to take the power supply for those devices either from phase-to-neutral or phase-to-phase – depending on the configuration of the three-phase supply.

Wikipedia has an article on three-phase power that explains the common connection schemes (Y or star where the three phases are wired to a common point, and delta where they are wired in a triangle). What is significant is that you will typically get a high and a low voltage depending on how you connect to a three-phase system. For example in the US a common Y three-phase service will give you 120 V phase-to-neutral and 208 V phase-to-phase.

A true 3-phase (as in needs to connect to all three phases) low-voltage power supply will probably be quite expensive. But you also don't need one. Unless you are building an "industrial" device all you need is a "normal" low-voltage power supply that is designed for the voltage that you'll be connecting it to.

All you need to do is to confirm the voltage that you'll be using and check that your power supply is rated for it. Many low voltage supplies are designed to be "universal" and you'll see a rating like 100-240 V, 50-60 Hz. That's likely to work on most three-phase supplies as long as the connection isn't phase-to-phase in a part of the world where the high voltage is in the 400 V range.

• There are a lot of 3-phase PSU. But in fact not many provide a voltage suitable for an arduino. Example: [pulspower.com/index.php?reqNav=product&objectId=21], which is a device using explicitely two phases of a three phase system, not from a two phase system. The manufacturer also has real 3-phase PSUs, but only with Vout beginning with 24V. Nov 29, 2015 at 19:15
• I'll correct what I wrote. Supplies like that exist, but if you're just doing something small with an Arduino are way bigger (and probably way more expensive) than what is required. The one you linked to is capable of providing 8 A at 12 V DC and is designed for mounting in a control enclosure. I'd expect you're paying a premium for that too. So it really depends on what you need – if you're looking for industrial grade gear, then that is a good example of what is available, but if you're just looking to provide power for an Arduino in a 3-phase environment, you can get by with less.
– dlu
Nov 29, 2015 at 19:48
• 3-phase transformers are not cheap in general and low-voltage 3-phase transformers are very niche since taking such a small amount of power from 1 or 2 phases won't affect PF very much. Nov 29, 2015 at 19:55
• The one I linked is in the wild for about 100 € without VAT. Which is a pretty good price considering the specs. But that won't help our friend with tapping the powerline running over the rice field. (This could explain, why he has no neutral). :P Nov 29, 2015 at 20:18
• €100 is not a bad price, but still way more that you would have to spend to power an Arduino in a three phase environment. It really depends on what the goal is… But for prototyping I'd be tempted to spend less – at least to start with.
– dlu
Nov 29, 2015 at 20:23