# Are 220 V to 110 V voltage converters safe?

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#### tempos

##### Member level 2
Are 220 V, 50 Hz to 110 V voltage converters safe?

I ended up with a few electronic devices: a phone charger, a battery charger, a drilling machine, an alarm clock with radio, etc., that are designed for 110 V, 60 Hz and which I want to power from a 220 V, 50 Hz outlet. I also have a converter **broken link removed** that I never used.

I found a site (Electricity in Europe. Plugs, Adapters, Converters. Voltage, Power, Frequency.), apparently well done, containing advises regarding (not) using voltage converters. However, the author, John Bermont, makes some statements (see 1 and 2) that, at least for me, appear quite odd.
Is the voltage converted by cutting the lower lobe of the sinus, as this man claims, and is a clock powered with the help of a 220 to 110 converter really affected by the frequency of the network and so running at only 5/6 with disastrous consequences regarding keeping the correct time?

1) https://www.enjoy-europe.com/hte/chap11/images/ElectricityConverted-520.jpg

...
WHAT IS A CONVERTER?
Definition
A "converter" is an electronic device designed to reduce 220 volts to 110 volts. It does this by cutting off half of the peak-to-peak sine wave. Very simple. Thus, the electricity varies from zero to max volts and back to zero. It does not go to negative volts. It stays at zero volts for half of the sine wave. Therefore, what comes out of a converter is on-off power, at a frequency of 50 Hz. See the red line in the graph above.

Source: https://www.enjoy-europe.com/hte/chap11/converter.htm

2) Frequency Effect
Do not bother bringing a plug-in electric clock or clock radio to Europe. These devices, which generally operate on AC motors, will run at only 5/6 of the speed for which they were designed because the speed is determined by the electric frequency. If you bring your electric alarm clock, assuming that it works on 240 volts, and set it at 6 pm when you check into the hotel, it will read only 11 pm when it is midnight, and only 4 am when it is 6 am. You will probably miss breakfast. You need a battery powered travel alarm.

Source: https://www.enjoy-europe.com/hte/chap11/electric.htm

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#### chuckey

##### Advanced Member level 5
Clocks are synchronous electric motors. Their time keeping is down to the fact that at the generator stations, the mains frequency is kept very accurately over a period of 24 hours*. The clocks lock on to the incoming frequency so running a clock designed and calibrated for 50 HZ will run fast if fed with 60 HZ.
The action of a "voltage converter" will lead to small transformer fed chargers and such devices overheating, because their transformer primaries are being fed with DC, causing core saturation. They would work with SMPS but these would probably not need one. Stick to a transformer type of voltage converter.
Frank
* During the day when the generators are under a heavy load, they tend to run slower, so the frequency drops, so clocks run slower. At night time the generators are sped up to get back the time they lost during the day, so clocks run faster.

#### KlausST

##### Super Moderator
Staff member
Hi,

in europe the the mains frequency is kept satble with two systems.

Since mains frequency is a parameter if there is too much or too low power there are stations to compensate for over- and underpower.
Tennet is one of the companies who adjust frequency.

In a first stage every second the frequency is measured. if it is 49.98 ...50.02 Hz there is no reaction. If it is 49.98 down to 49.80 there is a linear corretion with sourcing extra power from 0...3000MW into the net.
From 50.02 up to 50.20 Hz it´s the other way round sinking power 0...3000MW from the net.

The second stage integrates the frequency error and compensates this error over long time (day). This ensures that a mains frequency driven clock is precise.

*****

We build mains frequency measurement devices and i can´t remember a deviation of more than 0.05Hz in the last years when readnig the actual display. (But i don´t look 24 hours a day...)

Klaus

#### joe90uk

##### Newbie level 4
There are multiple answers to this question. Lets start with 'is it safe' and the answer is yes if you are going to continental Europe which is mostly 220v AC 50hz. The UK is around 230-240v AC 50hz but I am told that there are plans to reduce it to 220v in the coming years. It would not be safe to use a converter rated at 220v in the uk. I am not familiar with your converter but any mains converter being linear or switching, will still give 110v AC output +/- 5%. The problem will be the frequency. This issue has been covered by other writers. I live in the UK but most of my equipment and appliances come from the states so I am familiar with most problems. Here is a brief overview of what works and what doesn't.
Charging devices such as phones, battery, laptops and tablets will work fine. Basically, anything that normally runs on a battery but has a separate charger.
Anything with a motor but no battery such as drills, mowers and razors without a battery, will run slightly slower.
Anything with a clock which does not normally run from a battery such as clock radios, microwaves and satellite receivers will have clocks that don't keep time.
And finally, don't forget to check the wattage rating of the converter is sufficient for the items you are running.

#### KlausST

##### Super Moderator
Staff member
Hi,

In the 1930s up to 1980s electric clocks were driven by the frequency of the power grid but the technology has advanced in the meantime and the clocks use now a 32,768 Hz crystals to keep the time.

A big manufacturer (SIE***S) includes in it´s latest electric stoves clocks driven with mains frequency!!!
A horror for me as an electronics developer.
In an area with some overtones in the mains frequency the clocks are running fast. And the user can not change it - or he builds heavy 3kW filters in mains line.

Definitely a step back....

Klaus

#### tempos

##### Member level 2
Hi,
A big manufacturer (SIE***S) includes in it´s latest electric stoves clocks driven with mains frequency!!!
My converter has two settings:

1) Low: 0 - 25 W for radios, battery chargers, electric shavers, etc..
2) High: 26 - 2000 W, only for short intervals of time, max. 30 minutes, for clothes irons, hair dryers, etc.. High mode is not for electronic devices.

So, basically I can power electronic devices up to 25 W and only using the Low position of the switch.

Unfortunately I do not have a schematic for the converter. I do not really know how it works in the two modes and why the 110 V output voltage should look like this: https://www.enjoy-europe.com/hte/chap11/images/ElectricityConverted-520.jpg (as the author John Bermont says). Why should the voltage be a half wave rectified signal and not a sine wave?

#### dick_freebird

##### Advanced Member level 5
I picked up several isolation transformers for dirt cheap at
a local electronics surplus place, they have the primary
winding center tapped for either 240V or 120V use. You
won't find much safer, provided you can get by with only
a kW or so. You'd like one that is meant for your mains
frequency, or built for 50/60Hz both.

Nobody loves heavy iron anymore, everyone wants to be
a solid state smart guy, so these bricks go pretty cheap
(and often, can be found in older audio and computer
equipment for nothing, if you hit the right dumpster).

#### tempos

##### Member level 2
Are there 220 to 110 V travel converters (at least 500 W) that do not use transformers?

#### betwixt

##### Super Moderator
Staff member
Dick, the issue isn't converting the voltage, it's converting the frequency. Transformers are completely safe, if bulky but even if they will work on 50Hz or 60Hz, they can't convert one to the other.

Tempos, the answer is no. I will qualify that by saying it doesn't have to be a big iron transformer, it can be a two stage process using SMPS and inverter technology. Basically, converting the incoming AC, whatever it's frequency, to DC then convertng it back to the desired voltage and frequency with a bridge inverter.

Brian.

#### tempos

##### Member level 2
My converter looks like this (see also the attached file):
Most likely it does not convert the frequency. It will generate 110 V and 50 Hz not 60 Hz.
I am looking for a schematic for this converter or similar ones. It appears to have a transformer inside because it is relatively heavy but is that transformer capable to output up to 1875 - 2000 W for 30 minutes?

#### Attachments

• Conair Travel Voltage Converter TS702CRC.png
175.8 KB · Views: 25

#### betwixt

##### Super Moderator
Staff member
I suspect those may be 30 Chinese minutes, for everyone else it will probably combust after two or three minutes.

Look at isolating transformers for use in building construction to see the proper size for a transformer with that rating. They come in boxes with a carrying handle because of their weight.

If you can open it, look for a ferrite cored transformer and several power transistors on heat sinks, that would be the clue that it was an SMPS converter.

Brian.

#### tempos

##### Member level 2
I have found another 220 V -> 110 V, 1600 Watt converter labeled as solid state.
see: **broken link removed**
It is designed only for non electronic devices.

I can not open my converter because I am afraid I will damage something inside. It is quite possible that it only uses the transformer for mode 0 - 25 W and another kind of converter for 26 - 1875 W.

#### betwixt

##### Super Moderator
Staff member
I woud be equally cautious with that unit. From the warning about 'non-electronic' I would guess it produces a modified sine (almost square wave) output and there certainly isn't enough space inside it for a conventional transformer. A transformer rated to run 1.6KW (1600VA) would look something like these:
https://www.screwfix.com/c/electrical-lighting/site-transformers/cat830094

Can I ask why you need to do the conversion. If you are moving from a 110V to 220V region it would be much easier to buy one of those big transformers and forget the frequency being different. Only devices with motors inside them or relying on the line frequency to keep time will notice the difference and that eliminates most low power equipment. When I moved back from the US to Europe the only thing that didn't work with a step-down transformer was an ancient digital clock but the cost to replace it was vey small and as previously pointed out, the majority of time keeping devices these days use their own timing reference anyway.

Brian.

#### D.A.(Tony)Stewart

##### Advanced Member level 5
A smaller 2:1 transformer will work for small electronic loads.

If clocks depend on AC frequency, they wont work. If they use a crystal, it will work.

- motors will be challenged by the (poor) quality of cheap converters.

- cheap adapters are good for hair dryers since they rectify the AC into DC and use one filament wire as a series resistor for low power, then others for more heat.

- otherwise, cheap converters can be problematic using a series diode to rectify voltage.

It might be better to replace than buy a high quality converter.

#### tempos

##### Member level 2
cheap adapters are good for hair dryers since they rectify the AC into DC
A hair dryer has likely an AC motor. If a cheap converter rectifies AC into DC then how does the motor work?

#### Anna Conda

##### Banned
often the motors are DC motors...

Orson Cart

### Orson Cart

Points: 2

#### tempos

##### Member level 2
If the 220 -> 110 V converter is for 110 V, 60 Hz hairdryers and nothing else is specified then it should power any kind of hairdryer (< 2000 W) that works when plugged in an outlet in US.

AC HAIR DRYERS VS. DC HAIR DRYERS
https://www.visual-makeover.com/hair-dryers/

If the output of the converter looks like in the diagram I posted in my first message then the 110 V half wave rectified signal should act as an AC 110 V, 50 Hz (not 60 Hz) but a poor quality AC quite far from a sinus function.

#### Orson Cart

##### Advanced Member level 3
Obviously if you have 110Vac elements and 110VDC motor, then using a diode to take out half the voltage would allow it to run on 220Vac, this is in fact commonly done....

#### tempos

##### Member level 2
Obviously if you have 110Vac elements and 110VDC motor, then using a diode to take out half the voltage would allow it to run on 220Vac, this is in fact commonly done....
Yes but the same voltage looking like a 220 V sinus with the lower (negative) part lost has to be able to power a 110 AC motor and this will not happen.

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