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I am moving to Poland this summer and would like to take my two HEPA air filters with me (it really helps with my breathing, especially when the air is so polluted in the region). However, they are rated for 120V at 60Hz while the only reasonably priced transformers change the voltage to ~120V, 50Hz. I am not sure what else to do because I have have severe breathing issues and even my skin reacts to something there (hard to figure out what this is). A 50 to 60Hz transformer would be more expensive than ordering a new filter from the UK (I can't seem to find these filters anywhere in Europe except on amazon.co.uk), which I would like to avoid doing.

Will a ~50W motor (120V, 60Hz) accept 120V, 50Hz power without issue, especially since this is in a fan, which ought to keep it cool?

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    That is why I plan to use a transformer to get ~120V power. The voltage is very easy to deal with. Frequence is NOT so simple (or at least cheap, anyway). –  Jan 27 '16 at 13:11
  • I edited the question to make this more clear. But why would I need 220V? A tranformer will drop the voltage down to 110-120V very cheaply. –  Jan 27 '16 at 13:13
  • @JonathanReez a transformer is a device that plugs into the 220 V wall socket and uses that electricity to provide a 120 V socket, into which a US appliance can be plugged. This allows one to power a 120 V appliance from a 220 V socket. – phoog Jan 27 '16 at 13:27
  • Even if this does not answer your question, my first shot at Amazon Spain showed filters ranging from 50 to 400 €. – Diego Sánchez Jan 27 '16 at 14:18
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    Isn't this a question for electronics.stackexchange.com? – IAmJulianAcosta Jan 27 '16 at 14:27
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    @IAmJulianAcosta I suppose it has already been asked and answered there, but it is also relevant to travel and ought to be represented here, too. Thefact that the OP is moving to Poland, however, suggests that thisquestion ought to be on expatriates. An expat is more likely to have experience with this, anyway, as voltage transformers are bulky and inconvenient for travel. – phoog Jan 27 '16 at 14:36
  • @phoog Well, I have been traveling a LOt in Europe, and this is time is more long term. I don't know how long I'll be there, it may only be a few months, then another country. –  Jan 27 '16 at 16:46

3 Answers3

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The answer is unfortunately not as simple as stated by CMaster.

If the device contains an AC motor directly driven by the mains voltage, reducing the mains frequency will indeed cause the motor to rotate slower, but it may also overload the motor. It is difficult to easily explain the physics behind this, but basically, a motor needs a larger magnetic core to run on a lower AC frequency. If the magnetic core is not large enough, it might saturate during the AC cycle (with is longer if the frequency is lower), cause a significant current increase and finally the motor to overheat. Electrical motors are also often cooled by a fan attached to the motor shaft, so reducing the rotation speed of the motor may lead to insufficient cooling of the motor block itself.

The issue with the physical dimension of the magnetic core also applies to transformers. If the device contains a transformer designed for 60Hz, it may overload if operated on 50Hz.

Without knowing the exact design of your device, it is impossible to answer your question. If you won't risk the device to break or in worst case overheat and catch fire, your only reasonable option is the get a confirmation from the manufacturer, that the device can be safely used on 50Hz mains.

Tor-Einar Jarnbjo
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  • Although I agree with your assessment: that asking is best, I would like to say that the way UL and CE requires over engineering many devices probably work at both. Additionally the way manufacturing works it is likely that all magnetics (motors and transformers) work at both frequencies, and have wiring for both 120V and 240V (most motors are wound differently, so the voltage is less likely to be compatible than the frequency) – Sam Jan 27 '16 at 17:20
  • @Sam Hence why I will certainly have a transformer to drop the voltage, but was unsure of the frequency! –  Jan 29 '16 at 18:27
  • They seem to think it will be fine but may have a shorter life. I have a hard time peeking in to see how the motor is placed. It can only draw about 50W, so an extra 10W even seem like too little heat to cause it to catch fire. I mean, you can even put your hand on an LED drawing 13W without it hurting too much… –  Jan 29 '16 at 18:28
  • @zagadka314, It's not going to draw 10 more watts necessarily, you have to understand how current, frequency, torque and power interact and none are linearly related to eachother. – Sam Jan 29 '16 at 18:35
  • @Sam Well, I am unsure of the power differences, I primarily meant that 10W of heat really isn't THAT significant. I doubt it could cause heat to build up enough to really risk damaging a simple electric motor and plastic casing. –  Jan 29 '16 at 18:37
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    @zagadka314 Who says that the engine won't dissipate a few hundred watts more heat if connected to 50Hz mains? – Tor-Einar Jarnbjo Jan 29 '16 at 19:17
  • @Tor-EinarJarnbjo Would? First off, there is no engine. Calling a motor an engine is inaccurate in the general use of the word in society. You might as well call a fuel cell a battery if you are going to do that. Next, why would you think a 50W motor would put out a few hundred watts more heat? It would have to draw at least a few hundred watts and there doesn't seem to be any physical reason to believe it would do so. It should draw more or less the same amount of power but a larger percentage of that power will end up as heat. Even 50 watts of heat isn't THAT much. –  Jan 30 '16 at 13:55
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    @zagadka314 Please feel free to ruin your expensive equipment if it is more important for you to nitpick on my wording as a non-native English speaker. If you believe to understand the physics and know what will happen if you run an electrical motor at a lower frequency than what it was designed for, why do you ask here at all? And just to repeat what I already wrote in my answer: If the magnetic core of the motor saturates during the AC cycle, it will draw a much higher current (several times higher is not unrealistic) and hundreds of watt of extra thermal energy is a realistic problem. – Tor-Einar Jarnbjo Jan 30 '16 at 14:31
  • @Tor-EinarJarnbjo My issue wasn't your English. I discuss motors vs. engines often, I am an EV enthusiast. Every few months someone feels like arguing that my car has an engine because motor = engine to them. I'm sorry if I offended you by causing you to think I was attacking your English, I must say, your writing is extremely good, and better than the writing of many of my native English speaking family members. I also see that I mixed you up with a third party. I mistakenly thought someone was trying to add some hyperbole to the matter. And for that, I also apologize. –  Jan 30 '16 at 20:43
  • @Tor-EinarJarnbjo Based off your name, would I be wrong in assuming that you are from Norway? I made a search concerns 50 Hz power through a 60 Hz motor with some extra keywords based on your concerns and I found this site: http://www.usmotors.com/TechDocs/ProFacts/50Hz-Operation-60Hz.aspx If I ran the unit on 104V, it seems to keep that pattern. Or 109V at +5%. Since Poland is 220V, I would think the transformer should take it down to 110V, very close to that voltage. I do not know if the motor I have would be of the kind this is concerned with, especially since mine is so small. –  Jan 30 '16 at 20:48
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    @zagadka314 You are of course right that reducing the voltage will mitigate a potential overload due to lower AC frequency, but you cannot deduct a general rule from the table you are linking to. As you can see on the web page, it applies only to a few specific motor models from this manufacturer. For other models, you are referred to the engineering department for further advice. – Tor-Einar Jarnbjo Jan 30 '16 at 22:16
  • If you want to keep this discussion going, you should however move your question to electronics stackexchange. Someone there will be able to explain better all that might go wrong: http://electronics.stackexchange.com/ – Tor-Einar Jarnbjo Jan 30 '16 at 22:23
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Your fan, or its power supply, should have a label on it indicating the acceptable power inputs. You should find something like:

  • Input AC 120-240V 50-60Hz

This gives the range of voltages and frequencies that are acceptable. If it says "50-60Hz" then you are OK at 50Hz. (Or any other range that includes 50Hz, but other ranges will be very rare.)

If it says something like:

  • Input AC 110-130V 60Hz

then you are not OK. As a rule it will be cheaper to buy a new unit than a frequency converter. However you may be able to get an alternative power supply for the unit.

DJClayworth
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If the system is simple enough, it shouldn't be a problem. The motors will work, just spin slower. If there's more complicated electrics going on, or slowing the speed of the fan will effect the actual role of the device, then you might have bigger problems.

Edit: While this answer covers "does it run", other answers have shown that there additional (potentially safety related) concerns. Please see them.

CMaster
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