Using Arduino in BANNED

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dir
 
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Using Arduino in BANNED

Post by dir »

I would like to use the arduino for a project I am doing in Ghana, and I was curious if the Arduino would work with an adapter or if I need to get a voltage regulator.

Basically the arduino is switching an AC motor on and off on a timed interval. The AC motor is connected to the Arduino by a powerswitchtail. If the arduino receives the correct voltage this should be fine right? If I understand the powerswitchtail correctly the arduino is sending it 5v DC and the powerswitchtail converts that to AC? So the fact that the Arduino is being powered by 230 Volts shouldn't affect the digital output pins?

Here's the webpage of the powerswitchtail: http://powerswitchtail.com/default.aspx

According to http://en.wikipedia.org/wiki/Mains_powe ... _the_world Ghana's electrical system is 230 Volts at 50 Hertz and uses D and G type plugs.

So would I just need an adapter? The 9v regulated DC power adapter from adafruit says that it works in Europe, though granted I think that is 220v not 230v. http://www.adafruit.com/index.php?main_ ... be880c8c2a

Or would I need a voltage regulator like this one: http://www.110220volts.com/ATVR-2000.html

Thanks for any help you can provide!

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Franklin97355
 
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Re: Using Arduino in BANNED

Post by Franklin97355 »

Since the powerswitchtail looks to be designed for the US I would look at designing your own circuit using a Solid State Relay that would be sized to your input and output needs in BANNED. You will need power for the arduino that you should be able to get from a USB 5v power supply like those used to charge your cell phones or MP3 players. Depending on the 'timed interval' you may not need an Arduino at all and could get by with regular ic chips like the 555.

uhe
 
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Re: Using Arduino in BANNED

Post by uhe »

dir wrote:If the arduino receives the correct voltage this should be fine right?
Right, as listed on the website the recommended input voltage for a Duemilanove is 7-12V .
dir wrote:If I understand the powerswitchtail correctly the arduino is sending it 5v DC and the powerswitchtail converts that to AC?
No, on the powerswitchtail you have 3 connections 120v input, 120v output and an "enable input" where you connect the arduino to. When you apply a high or low level (I havn't looked at the datasheet) to this input you can enable the connection from the 120v input to the 120v output, so that current can flow through the powerswitchtail.

About the website:
Patent Pending.
I'd say there is prior art all over the world!
Switching capacity: 3A @ 250VAC
You need to remember that! Since you're taking about powering an AC motor I'd think 3A is a little low.
dir wrote:So would I just need an adapter? The 9v regulated DC power adapter from adafruit says that it works in Europe, though granted I think that is 220v not 230v.
Yes a simple wall wart should be enough and the grid in europe is 230v. OTOH every wall wart I've seen from laptop to mobile phones have an input range from 110v to 240v so it shouldn't matter.

As franklin97355 said a 555 timer might be better suited in terms of price and availability even ofside in Ghana. Besides that, a 555 timer can simply be replaced in case of failure, a microprocessor has also to be reprogrammed!

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floresta
 
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Re: Using Arduino in BANNED

Post by floresta »

dir:

The circuit diagram for the PowerSwitchTail shows that it consists of a 5v relay, two surge suppressors, an LED with its series current limiting resistor, and three connectors. If your motor is really small then this device may be able to control it. You would need adapters to match the AC input and output connectors.

You would probably be better off doing what Franklin has recommended. There are many inexpensive solid state relays available. Just mount one in an enclosure with appropriate (for Ghana) AC connectors and you are all set.

In either case, for powering the Arduino you will need an appropriate power supply - one that can supply about 9 - 12 vDC from a 220 - 240 v AC supply.
Yes a simple wall wart should be enough and the grid in europe is 230v. OTOH every wall wart I've seen from laptop to mobile phones have an input range from 110v to 240v so it shouldn't matter.
The last time I looked Ghana was in BANNED not Europe - but that is irrelevant. Many wall warts do not have the wide input range mentioned here so you must check to make sure that the one you use does.

Don

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dir
 
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Re: Using Arduino in BANNED

Post by dir »

Thanks so much for your help!

You are right. We have a smaller AC motor here, and it works perfectly with that, but we were hoping to upgrade to a 1/2 hp motor... and that will be 8 amps.

It's this motor http://www.mcmaster.com/#5990k36/=7wzpzr (I think the link highlights the 3/4 hp but we will be using the 1/2 hp

What solid state relay would you recommend?

I've done a fair amount of work with microcontrollers, but I'm nervous around mains electricity. Is there a good tutorial for how to wire these?

... and yes, I probably should go with a 555 timer, but I like being able to quickly adjust things and prototype. That sounds like a good idea for the final version.

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adafruit_support_bill
 
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Re: Using Arduino in BANNED

Post by adafruit_support_bill »

Most manufacturers recommend a 25A SSR for 1/2hp @ 240V. Here is Opto-22's data sheet with application notes: http://www.alliedelec.com/Images/Produc ... 1-0512.PDF

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dir
 
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Re: Using Arduino in BANNED

Post by dir »

So, the Opti-tec 240D25. 240 VAC, 25 Amp, DC Control Solid State Relay is probably the one I want.

This may be a stupid question, but will the fact that the mains in Ghana is 50 hertz and not 60 hurt the motor at all?

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adafruit_support_bill
 
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Re: Using Arduino in BANNED

Post by adafruit_support_bill »

It will jut run a little slower.

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floresta
 
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Re: Using Arduino in BANNED

Post by floresta »

It will jut run a little slower.
And probably a lot hotter.

Don

minerva
 
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Re: Using Arduino in BANNED

Post by minerva »

Basically, the voltages of the mains power supply all over the world fall into two possible categories; 110-120 V or 220-240 V.

Some devices intended for use in the US, for example, quote their designed power voltage as 110 V, some say 115 V, and some say 120 V. But they should all work fine in any 115-V-or-so country.

There is always a few percent of error here and there regarding the actual RMS voltage on the wall socket.

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floresta
 
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Re: Using Arduino in BANNED

Post by floresta »

Minerva:

You are missing the point. Other than the mysterious parameter that you call "power voltage" your comments are basically correct as far as lights and heaters go but are not correct when motors are concerned. If you run a light at a lower than rated voltage it gives out less light (and lasts longer). If you run it at a higher than rated voltage it gives out more light and gives out more quickly (sometimes instantaneously). If you run a motor at less than its rated voltage it draws more current (assuming the load hasn't changed) and therefore runs hotter, sometimes dangerously so.

The last few posts, however, have been dealing with frequency, not voltage. As far as lights and heaters go there will be little or no difference in operation between operation at 50 Hz compared to 60 Hz. Not so for inductive loads such as motors.

Don

Entropy
 
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Re: Using Arduino in BANNED

Post by Entropy »

To be a bit more specific, if I recall correctly:
Many cheaper AC motors have their rotation speeds tied to AC frequency. If operated at a lower frequency than they were designed for, they will rotate slower.

The problem is that this reduces the back EMF of the motor, which will cause it to draw more current.

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floresta
 
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Re: Using Arduino in BANNED

Post by floresta »

Many cheaper AC motors have their rotation speeds tied to AC frequency.
Actually "cheapness" is not the best way to categorize this.

As I remember:
Synchronous motors run at a speed that is determined by the supply frequency and number of poles on the motor.

Induction motors run at a speed that is slightly less than that of a similar synchronous motor. The mass produced shaded pole motors used in fans, etc. fall in this category so your statement is supported here.

Series motors may run at a wide range of speeds. Since many really cheap motors fall in this category it would be the cheapest motors that are not closely tied to the AC frequency.

Don

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opossum
 
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Re: Using Arduino in BANNED

Post by opossum »

Universal AC/DC motors run at a speed determined mostly by voltage and load.

I think, as a general rule, that if a motor uses a starting capacitor, relay, or inertia switch then it *must* be run at the designated frequency.

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adafruit_support_bill
 
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Re: Using Arduino in BANNED

Post by adafruit_support_bill »

I have a few sizeable European 50 Hz motors (3-5 Hp, single phase) that I regularly run on 60 Hz. They run 20% faster than rated, but otherwise have no problems.

I haven't tried running 60 Hz motors at 50 Hz, but it makes sense that it would be more prone to overheating that way.

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