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I need a step up converter for a 5.1A, 120V vibration motor I have in the US that I need to use in Ireland. The motor runs at a fixed frequency of 30Hz in the US. If I step up to 230V for Ireland will the frequency change?

Here's the unit for those interested: Technical details of the motor

I didn't think I would get a response from the company but I did and they replied that it would not work in Ireland. The frequency change causes overheating issues.

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    \$\begingroup\$ You need a step-down transformer to run the motor in Ireland, no? If it's synchronous or an induction machine it will run at a lower speed due to the 50Hz in Ireland vs. 60Hz in the US. \$\endgroup\$
    – John D
    Commented Nov 20, 2016 at 19:49
  • \$\begingroup\$ The US power grid is 60Hz, the difference between 50 and 60Hz is not usually a big issue for most motors and transformers (with the exception of mains clocks which would run 1.2 times slower). But as John mentioned you need a step down transformer because your "stepping" from a higher mains voltage down to a lower voltage for the motor, 99% of step-up/step-down supplies have no effect on frequency (because it would cost 10 times as much as it would need way more than just a simple transformer) \$\endgroup\$
    – Sam
    Commented Nov 20, 2016 at 20:38
  • \$\begingroup\$ I don't even know where to begin. Can you please provide more information about the motor, and maybe a picture of it? What is the motor in? Does it have a faceplate with information on it? You say it "runs at 30 Hz" but that seems odd since the US is a 60 Hz country. In general, if a motor is rated for 60Hz input and is not listed for 50 Hz operation, there is a chance it could overheat at 50 Hz, unless the voltage is reduced correspondingly. But it depends on the motor type. \$\endgroup\$
    – user57037
    Commented Nov 21, 2016 at 0:33

2 Answers 2

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  • The power mains voltage in Ireland is 230V and the frequency is 50Hz.
  • The power mains voltage in the USA is 120V and the frequency is 60Hz.

To power a 120V motor from 230 volts, you need a step-DOWN transformer.

It is very unlikely that you have a "30Hz" motor. There is no commonly available mains utility power on this planet that operates at 30Hz.

If your (likely) 60Hz motor is actually mains-frequency sensitive (which many/most motors are NOT), then it will operate at 5/6 the speed compared to North America (60Hz). Since you did not identify what this motor is for, you will have to make your own determination whether this is significant.

To answer your original question, NO, power converters (transformers, etc) do NOT change the power frequency. But for 98% of appliances, this makes no difference.

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  • \$\begingroup\$ It's a vibration system - they very possibly use Fmains/2 as their source. While they call it a motor it may be solenoid or "other electromagnetic means" based. So it MAY be synchronous or synchronous/2 or ... ? They'll want lower than 60 Hz if possible so some sort of /2 is quite likely. \$\endgroup\$
    – Russell McMahon ♦
    Commented Dec 4, 2016 at 23:49
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The device seems likely to be identical or similar to the "Bulletproof" - Whole body vibration plate. Appearances vary with model but a number of plates appear to use the same core. The above cited page provides about as good a general description as is lkely to be available by user oriented pages.

They say

  • 30 Hertz fixed frequency
  • Motor: 1/4 HP motor running at 1,725 rpm

1725 RPM is the standard nominal speed if a 2 pole sinduction motor running on 60 Hz mains. [60 Hz = 3600 RPM. 2 pole synchronous = 1800 RPM. Induction motor nominally 'slips' at 1800-1725 = 75 Hz].

Images else where seem to show a standard motor under the plate with shaft horizontal. This suggests a gearbox of some sort is used - possibly a worm drive. Possibly other.

A gear ratio of 1725/30 = 57.5:1.
Elsewhere people say "29 Hz" = 59.5:1. 60:1 is not unlikely.

SO

If it is a 110 VAC 1/4 HP 60 Hz induction motor, as seems likely:

You need a 2:1 step down 230:110V (nominal) transformer* - these are standard items. You want one rated for 1/4 HP. This is nominally ~= 200 Watts BUT more is better and much more means load peaks are more easily accommodated.

BUT:

The 60 Hz motor will operate slower on 50 Hz mains - so vibration table will vibrate at about 30 x 50/60 = 25 HZ.
No major but may be noticeable to some.

And/but the motor MAY overheat on 50 Hz as the cysles are 20% longer and iron laminations may be drive further into saturation. There will be people "in the electrical industry" who can tell you how much of an issue this is liable to be.

IF the maker sells 230V units then buying a 230 VAC motor may be as cheap as any alternative (except that such companies seem to sell, based on price, units that must be gold plated or contain rare gems).

It is quite likely possible to find an Ireland sourced >= 1/4 HP motor that bolts straight in. Control panel voltages may need looking at BUT control may be zero to absent.

Same brand - slightly different appearance - motor visible (partially)

enter image description here

"Bulletproof" version:

enter image description here

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  • \$\begingroup\$ On the vendor's website they make multiple claims that the 30Hz vibration is CRITICALLY MAGIC. Which seems like an extremely dubious claim to me. Especially given the wide variety of height and weight of the users. But then in their email response to the OP, they claim the issue would be overheating from operating the 60Hz motor at 50Hz. That seems far more likely and believable to me. I would wager that operating at 25Hz would provide little or no difference in whatever benefits it is supposed to claim. \$\endgroup\$
    – Richard Crowley
    Commented Dec 5, 2016 at 0:41
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    \$\begingroup\$ @RichardCrowley Critical magic is also and ingredient in OFC cables and many crystal based products. In this case the plate system MA be resonant at 30 Hz so 25 Hz drive may not be as vibratulant [tm]. User loading may de-Q that 'somewhat'. \$\endgroup\$
    – Russell McMahon ♦
    Commented Dec 5, 2016 at 0:48
  • \$\begingroup\$ @RichardCrowley Datapoint only. I agree re potential overheating (as per my asnwer). I've actually seen this happen with a transformer. I had a transformer custom would in NZ to power lower voltage equipment for use in Taiwan. I told the transformer inder that it was for Taiwanese use but did not (as I should have) mention frequency of use. When tested in NZ (50 HZ) the transformer ran very hot but in Taiwan on 60 Hz it was fine. \$\endgroup\$
    – Russell McMahon ♦
    Commented Dec 7, 2016 at 5:41
  • \$\begingroup\$ What about adding a variable frequency drive after the transformer? Maybe is overkill for this application, but just in case... \$\endgroup\$
    – Adam Calvet Bohl
    Commented Dec 7, 2016 at 5:59

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