Convert US standard 115V to International 230V

[am1]

Hi all,

I am working on a medical device that operates at US standard 115V and 50-60Hz (with estimated 20Amps, we require 20A outlet). We are being considered for out first international sale that requires 230V and 60 Hz. Im assuming this is commonly done and will involve some kind of step down transformer. I haven't done something like this before... could someone please explain the process and components that would be needed to achieve this? Additionally, how would I go about testing said system after it is complete and prior to sending out the device (how would I test the now 230V system in the US to do verification testing)? Thank you all.

[Benta]

First, it's 230 V 50 Hz.
Second, it's usually done by design today, using power supplies with 90...250 V input range (switching PSUs).
The transformer solution is possible, but heavy and bulky.

I suggest a revisit of your design. Medical is normally not very cost sensitive, so there should be space for a respin.

[themadhippy]

First, it's 230 V 50 Hz.

not always,theres the odd place or 2  ,like south korea , were its 60Hz

[shapirus]

First, it's 230 V 50 Hz.

not always,theres the odd place or 2  ,like south korea , were its 60Hz

Actually a lot: https://en.wikipedia.org/wiki/Mains_electricity_by_country

[edpalmer42]

The easiest way to get from 120 to 220 volts is with an autotransformer.  Yes, it's large and heavy, but if you're looking at a 20A outlet, this probably isn't a portable device.

Benta is correct that it's usually 220V @ 50 Hz so the transformer won't fix that.  He's also correct that a universal input medical-grade switching supply is the preferred solution.  They're available as off the shelf items with whatever voltage and current ratings you need.  Note that the 'medical grade' tag will result in a significant cost increase.  But unless there are some specific reasons why a switching supply isn't appropriate, that's the recommended solution.  Using a standard, certified power supply may also help when it comes to electrical certification for your unit.

Ed

[am1]

Yes, this country in particular's standard is 230V and 60 Hz as mentioned.

My concern with changing design of the controls is in regard to IEC testing. Currently the device is IEC compliant, so changes to those critical internal components would likely require retesting which is costly and difficult to do logistically for a device of this size. Im sure the use of an autotransformer would also require some certification updates. The system has both a 24V and 26V PSU, I am assuming swapping both units out would be necessary?

[IanB]

I am working on a medical device that operates at US standard 115V and 50-60Hz (with estimated 20Amps, we require 20A outlet).

Note, US standard is 120 V (not 115), and is 60 Hz (not 50).

Note that, in general, a 20 A circuit can provide 16 A continuously. If your device needs 20 A continuously, you would need a 30 A circuit, which generally is not done with 120 V and you would need to move to a 240 V supply anyway. If you do move to a 240 V supply for the US market, then you would automatically be compatible with the overseas market you are considering.

[BeBuLamar]

I think the design should go back to really what kind of power your device requires? Is it DC and possibly multiple DC voltages? If so you would build a power supply to run from 85-250VAC 50-60Hz to supply the power. Some company can surely design and build such a power supply for you if you don't want to do it yourself.

[am1]

Apologies for any confusion regarding the system specs.
The device I am referring to has an operating voltage range of 115Vac +/-10%, and 50-60Hz, and uses a 20A outlet. The prospective customer would like 220-240Vac and a frequency range of 50-60Hz.

[themadhippy]

cant you just supply a separate step up transformer in a nice  box ,your device remains unchanged so still complys

[BeBuLamar]

If you expect to sell a few unit a step down transformer would be fine as your device is good for either 50 or 60Hz. If you expect to sell a lot you may want to consider building a unit what can work with both voltage.

[TimFox]

When I was working with a major manufacturer of large medical devices, they designed the actual system (power supplies, motors, etc.) to work at, I believe, 240 VAC, 50-60 Hz.
They supplied a suitable transformer in the main switch box with taps to cover a range of voltages from 100 to 440 VAC to satisfy their export market.
Depending on your power level, a common configuration for medical-grade power/isolation transformers is a toroid, e.g.  https://talema.com/products/medical-grade-toroidal-transformers/

[IanB]

I am working on a medical device that operates at US standard 115V and 50-60Hz (with estimated 20Amps, we require 20A outlet). We are being considered for out first international sale that requires 230V and 60 Hz. Im assuming this is commonly done and will involve some kind of step up transformer. I haven't done something like this before... could someone please explain the process and components that would be needed to achieve this? Additionally, how would I go about testing said system after it is complete and prior to sending out the device (how would I test the now 230V system in the US to do verification testing)? Thank you all.

Apologies for any confusion regarding the system specs.
The device I am referring to has an operating voltage range of 115Vac +/-10%, and 50-60Hz, and uses a 20A outlet. The prospective customer would like 220-240Vac and a frequency range of 50-60Hz.

If you were an engineer responsible for the design of the device, then you would know how to reengineer the internal design and would not be asking here.

So we have to assume you are not in that position, and that the device has an existing design that is already certified and you cannot modify it.

In that case, what you need is an external step-down transformer. Such devices are readily available, but you would have to select one that has the appropriate rating and certification for medical use. For a 20 A output it would need to be rated at 2.5 kVA or so, which would make it somewhat big and heavy.

(how would I test the now 230V system in the US to do verification testing)?

Since the USA has a 240 V domestic mains supply, you could test it in part with a 240 V outlet in the USA. (But in commercial/industrial settings the supply may be 208 V, which is not quite the same.)

However, an overseas supply may likely be 230 V Line/Neutral/Ground (as opposed to the US supply of Line/Line/Ground). If you wish to test with the exact Line/Neutral/Ground arrangement, you would need to consult the services of an electrical engineer to set up an appropriate test rig (a bit like TimFox mentions above).

[TimFox]

Side note:  "115 V" is an obsolete value for US single-phase power distribution.
Many nameplates for manufactured electrical gear are technically out-of-date.
Historically, it started out at 110 V, then 115 V, then 117 V, but has been 120 V (nominal) +/-5%, for decades, defined in standard ANSI C84.1 (1954).

[CaptDon]

Since the supply side is 220/240 and the output side is 120 you would be looking for a medical grade STEP DOWN TRANSFORMER. Using this external device to power your medical machine will not cause you to re-certify your machine. Simple. Done. Heavy. A toroid core auto-transformer will be the best design choice as an auto-transformer in general requires less copper and a smaller core than a transformer with totally isolated primary and secondary windings. You don't need isolation, only voltage correction. Be aware of what you are selecting!!

[Doctorandus_P]

It seems more logical to re-design the power supply itself instead of adding something to it.

Apparently it's already transformer based, so a different primary winding and a selector switch could be all that is needed.

[Odd-Job]

Hi am 1,
If you are expected to come up with an answer for your employer to fix this little problem, then all that is needed is a redesign of the primary winding's of your I.P transformer and maybe slightly more 'iron' lamination's.  If it is as you say 115 VAC @60hz with 20 A max then we are about 2.3 kVA worst case. 230-240 Vac will halve to 10 Amps so we are still around 2.3kVA. Suggest you get transformer supplier to wind   one with 2X120V windings that can be configured to be in parallel( 120 Volt 20 A) or series (240 Volt 10 Amps) either way about same kVA. Oh and make sure it is wound for 50 Hz so it will not overheat when humming @ 50 cps.
This is all said whilst assuming it is not a SMPSU in said unit. BTW is it a elephant defibrillator your involved in?
As Dr and us wrote;

It seems more logical to re-design the power supply itself instead of adding something to it.

Apparently it's already transformer based, so a different primary winding and a selector switch could be all that is needed.

[am1]

Thank you all for the suggestions, this is very helpful. It is a stationary robotic gait trainer for those wondering, and this is an existing system that I am now involved in. I am a bit confused by those mentioning it already being transformer, could you please elaborate, for reference the 2 PSU I am using in the system are Meanwell HRP-150-24 and HRP-600-36 units.

I am leaning towards something external due to the retesting and timeline concerns mentioned previously.. I was initially looking for step down transformers for the voltage conversion that would be a simple plug and play system. I would need the inlet transformer to accept the NEMA 5-20P power cord from our device and the transformer power cord in the appropriate cord type for Saudi (country in question). Is anyone familiar with options like this?

This is one example I came across that can be step up/down and has a toroidal core. It has a US plug type though so unsure of this unit in particular. Is there a reason to avoid this type of solution for a short term option until a system redesign can occur (reliability, safety, etc.)? I appreciate the advice from everyone, thanks.

https://www.vevor.com/variable-transformer-c_10755/vevor-step-up-down-transformer-voltage-converter-3500w-240v-110v-110v-240v-us-uk-p_010501337904?adp=gmc&srsltid=AfmBOoqn1_dCr4bXi68PtPUSOyP3iJSVOoAxBIdkQxGat7TJNGC4JEms_XI

[BeBuLamar]

If your machine is powered only by that 2 power supply then it can run on 230V as is. Just need the right plug.

[IanB]

Thank you all for the suggestions, this is very helpful. It is a stationary robotic gait trainer for those wondering, and this is an existing system that I am now involved in. I am a bit confused by those mentioning it already being transformer, could you please elaborate, for reference the 2 PSU I am using in the system are Meanwell HRP-150-24 and HRP-600-36 units.

Those power supplies are already universal voltage input units. You don't need to do anything, they will work just as they stand.

Haven't you looked them up already?

https://www.meanwell.com/productPdf.aspx?i=427
https://www.meanwell.com/Upload/PDF/HRP-600/HRP-600-SPEC.PDF

Ideally, you will just purchase and use an appropriate IEC power cord for the local market. I say ideally, because ideally the machines will have an IEC connector, and will not have captive power cords. If they have captive power cords, you will have to replace the power cords.

Also, those two power supplies at full load will consume about 900 W, or 7.5 A. That should be well within the capabilities of a NEMA 15 A outlet. Who has estimated 20 A and said you need a 20 A outlet? Does this device have additional power requirements other than those two Meanwell power supplies?

[am1]

Ideally, you will just purchase and use an appropriate IEC power cord for the local market. I say ideally, because ideally the machines will have an IEC connector, and will not have captive power cords. If they have captive power cords, you will have to replace the power cords.

Wow, not sure how I missed that with the PSU. That is great. There is a IEC C19 to 5-20P power cord on the device, and a power cable is connected to a Schaffner FN2090B-20-06 Filter, from there there are breakers for the each PSU. Looks like the filter has a 250V voltage rating, so the power cord or connector swap could be the fix here as yall mentioned.

Also, those two power supplies at full load will consume about 900 W, or 7.5 A. That should be well within the capabilities of a NEMA 15 A outlet. Who has estimated 20 A and said you need a 20 A outlet? Does this device have additional power requirements other than those two Meanwell power supplies?

The filter has a 20A rating, so perhaps that was the rationale. But I am slowly finding many questionable choices with the design as I have worked on this project... They are no longer on the project, but if I ask why specific choices were made electrically or software wise, I get a "Im not too sure" or "it was a fast solution".

[radiolistener]

As mentioned above, 240V mains usually has 50 Hz, while 120V mains have 60 Hz, so if you're needs to convert 120V@60Hz to 240V@50Hz it cannot be solved with simple 1:2 voltage transformer.

There are two approaches to solve it:

1) Old approach is to use umformer (electric motor + alternator). In your case the motor will work from 120V@60Hz and the alternator will generate 240V@50Hz. This way was widely used in old military equipment where voltage/frequency conversion is required (they often are designed for 400 Hz AC power source).

For example:



2) Modern way is to replace power supply in your equipment with switching mode power supply that support both standards.

[BeBuLamar]

He doesn't need to do any of that.

[radiolistener]

If you expect to sell a few unit a step down transformer would be fine as your device is good for either 50 or 60Hz.

No, step down transformer cannot convert 50 Hz AC to 60 Hz AC.

[TimFox]

Note that the op’s application involves equipment rated for operation at either 50 or 60 Hz, and the frequency conversion is not required.