For contact info, please see the Sci.Electronics.Repair FAQ Email Links Page.
Copyright © 1994-2004
All Rights Reserved
Reproduction of this document in whole or in part is permitted if both of the following conditions are satisfied:
1.This notice is included in its entirety at the beginning.
2.There is no charge except to cover the costs of copying.
We will not be responsible for improper operation, equipment or collateral damage, or expenses resulting from following the suggestions contained herein.
Answer: A simple step down transformer to convert from 220 to 110 V will probably permit them to work together (i.e., to play previously recorded tapes) but you will not be able to receive any cable or broadcasts.
Answer: Due to the high wattage of a microwave oven, converting the power will be costly. Sell it and buy a new one at your destination.
Answer: This depends on the specific appliances. See the remainder of this document!
Answer: Not without some modifications - which may not be worth it.
This should help you issues involved before you reach your destination!
Panel Components - Guide to Worldwide Plug/Socket Patterns and Power Mains has information and photos.
In addition, we deal with general issues related to adapting entertainment equipment and appliances to different power and the implications of reduced or increased voltage and frequency.
Note: this initial release will concentrate mostly on power issues. Later, we will deal with video, communications, and phones systems. For those, the documents: Notes on Video Conversion, Troubleshooting and Repair of Computer and Video Monitors, Troubleshooting and Repair of Television Sets, and Troubleshooting and Repair of Video Cassette Recorders, and others at this site may contain some of the information you seek on these other topics.
It would be nice if all you had to do was match up a plug and socket to make anything in the universe work together. Unfortunately, while this does work for some things - garden hoses, for example :-) - it rarely is as simple as this for electrical power, video, or communications.
This relates to what comes out of the wall socket. Nearly every country in the world uses an AC voltage between 90 and 240 V at 50 or 60 Hz. There may be some exceptions (like 600 V at 25 Hz powering portions of the New York City subway system or 28 V at 400 Hz on board an F-18 - but this is not something you are likely to need to deal with!) - if you encounter such unusual situations, we will be happy to add them to this document!
The three important considerations are:
There are a variety of approaches to adapting equipment designed for one power system to another.
In industrial or office buildings, 208 VAC will be available (since they use three-phase power but that is another story) and this may be close enough for most applications (though heating appliances won't be quite as zippy as if they were running on the proper 220 VAC and therefore your eggs may take a little longer to cook).
This refers to devices that consist solely of a pair (at least) of windings on an iron core. There are no other devices in a transformer beyond possibly a switch, indicator light, thermal protector, and/or a fuse or circuit breaker, and a plug or terminal block for input and socket or terminal block for output.
In the following, we assume that the two voltages are 110 VAC and 220 VAC. Similar comments apply if the ration is not 2:1.
There are several types including:
The relevant parameters characterizing a tansformer consist of:
However, they are heavy and costly and do not convert frequency. Thus, they may be unsuitable in some situations and there may be cheaper more appropriate alternatives. A *suitable* transformer large enough to power a space heater would weigh about 50 pounds and cost perhaps $200 - much more than the the space heater is worth.
Sometimes, it is only necessary to adjust the voltage by 10 or 20 V to be fully compatible. For example, this might be the case when using domestic Japanese gear in the U.S. and vice-versa. Their line voltage is closer to 100 VAC compared to our 115 VAC.
An easy way to change the voltage by 15 V (for example) up or down, is to obtain a transformer with a 110 V primary and around a 15 V secondary. The secondary current rating needs to be at least equal to the load requirements. Wire it up so the secondary is in-phase in series with the AC to the load to boost voltage (as shown below) or out-of-phase to reduce it.
Note: To obtain exactly the correct voltage will require a slightly higher or lower voltage transformer than this simple explanation would indicate since the input voltage will be slightly lower or higher than the transformer's rated input voltage. This is usually not an issue since precise voltage to an appliance or piece of electronic equipment is generally not required.
+------------+ | | AC In o-------+--+ | o )|| +----+ )||( 105 VAC Line Primary )||( Secondary )||( o )|| +---------o AC Out AC In o-------+--+ | 120 VAC to Load +-----------------o AC Out
Thyristor based converters are for converting from 220 VAC to 110 VAC without changing frequency with major restrictions:
Since all a thyristor (triac) can easily do is turn on - it has to wait until the end of the cycle to turn off - to get the same effective power from a 220 VAC input as a 110 V input will require a higher peak voltage with a duty cycle of much less than 100 percent. Capacitors in the power supply of typical electronic like to charge to the peak - BLAM! The high peak voltage can result in breakdown of underrated insulation and have other undesirable effects on devices like induction motors and transformers. Even equipment for which these are supposedly designed can be destroyed or may represent a safety risk since there can be much higher voltages inside than normal.
|| || |||||| |||||| |||||||| |||||||| |||||||||| |||||||||| |||||||||| |||||||||| |||||||||| |||||||||| |||||||||| |||||||||| |||||||| |||||||| |||||| |||||| || ||After smoothing, the result would be very similar to a sinusoid.
This more costly approach enables arbitrary voltage *and* frequency conversion but as we will se later, this is rarely needed. For an idea of how to design such a converter, see the section: Design of High Efficiency Power Inverters.
Cheaper models simply generate a square wave or modified sinewave at the appropriate frequency:
_________ _________ | | | | | | | | | | | | | | | | | | | | | | | | | | | | |_________| |_________|Modified sinewave:
_____ _____ | | | | | | | | | | | | ___| |____ ____| |____ | | | | | | | | | | | | |_____| |____|The nice thing about the modified sinewave is that its RMS and peak values match that of the true sinusoid (as well as other advantages in terms of harmonic content). If you don't know what this means, don't worry, Your life doesn't depend on it. One implication, however, is that heating loads and electronic devices which rectify and filter the input power will see the same effective voltage.
For many devices including all resistive loads, either of these approaches is adequate. However, devices with motors and/or transformers will be much happier with smoothed sinusoidal power. Switching power supplies (except universal types) will be underpowered with the simple squarewave inverter and may overheat running near full load.
The H-bridge MOSFETs are also only switches so they can be efficient. Plus, you're switching currents at the output voltage level which is a lot smaller than the current at the DC input.
You'll get a sine wave at the output and the whole thing should be simple and fairly cheap. The high frequency switching converter will be the hardest part to get going because of the wide adjustable output voltage range required, but I think it will still be easier than the "brute force" method.
Examples: fans and some blowers, can openers, pencil sharpeners.
Examples: some blowers, dishwashers.
Examples: washing machines, cloths dryers, circulator and other larger pumps, large furnace blowers, stationary shop tools.
Examples: vacuum cleaners, electric leaf blowers, many other portable line powered tools
Examples: TVs, some VCRs, computers (PCs and laptops), monitors, and some peripherals,
Examples: Stereo receivers, CD players, cassette decks, phones, some fax machines, some printers.
Examples: heating and cooling systems, garage door openers, etc. but most of these will have other components more severely affected.
"I would like to bring a variety of small to medium-sized Japanese electrical products (100V 50/60 Hz) with me when I move back to the U.S. (e.g., lights, rice-cooker, cassette player, VCR...) Individual transformers like those sold in travel shops are quite expensive. Is it possible buy a large number of small stepdown transformers -- or to make them as kits? Any advice would be greatly appreciated."First, for some of these like the VCR, the 15% difference between 115 VAC and 100 VAC may not matter. The only way to be sure is to check with the manufacturer.
For others like the rice cooker, it too may be ok if it uses a thermostat to control its heating element.
However, the simplest way to reduce 115 to 100 VAC is to buy or construct an autotransformer.
To construct one, you need a stepdown transformer with an output of about 15 V (for this example) and a secondary current rating at least equal to your total current needs. Then, the primary is connected to the line and the secondary is wired anti-phase in series with the loads and the line.
For devices using AC adapters, I would just replace the AC adapters with a US version.
With greatly excessive voltage (i.e., running a 110 V light bulb on 220 V), burnout will be nearly instantaneous - the bulb may even explode.
With reduced voltage, the light output will be reduced and life will be extended dramatically as well. However, efficiency decreases faster than voltage so it doesn't make sense to use bulbs on lower voltage unless they are in a hard-to-reach spot as the energy cost dominates. Extending the life of a 25 cent bulb just doesn't save money in the end especially if a higher wattage or additional bulbs must be used to make up the light reduction.
With greatly excessive voltage, heating devices will blow a fuse or internal thermal protector, the AC fuse or circuit breaker, or burn out.
An induction motor is a nearly constant speed drive. Reduce the voltage and it will still try to maintain almost the same speed. Where the load is constant, this means that it will draw greater current to compensate for the reduced voltage (remember: P = constant = V*I). This will result in excessive heating and stress. The equipment may fail to start properly at all or cycle on its thermal/overcurrent protector. Its life may be shortened or it may burn out quickly.
Excess voltage isn't good either since the construction may result in magnetic core saturation which will also result in overheating, added noise (hum), and lower efficiency.
These share many of the characteristics of induction motors in that they will attempt to maintain the same power to the load. Thus, at low line voltage, they will draw additional current and internal parts may be stressed to the point of (possibly catastrophic) failure. Unlike induction motors, this is much more difficult to predict as it is highly design dependent.
Usually a slight reduction or increase in voltage will not affect the performance or longevity. However, unless specified as a universal input (90 to 240 VAC) or where specific recommendations are available, remaining within a 10 percent window is best. This is especially critical on the low side when running near full load.
Running a non-universal switching power supply from a squarewave inverter result in overheating and subsequent failure near full load. The reason is that the peak value of the input waveform is about 7/10ths of that from the normal AC line and the current must increase to compensate.
How much excess voltage is acceptable is not something that can be determined without testing. Some transformers are designed very conservatively (bigger cores, more copper, etc.) while others just barely get away with running on the nominal line voltage.
Certainly, 2:1 will be too much for almost any transformer. You may get away with a 25% increase without too many problems.
It is possible to test for this by slowing increasing the input voltage while monitoring input current. Up until saturation, it will increase linearly with voltage. As saturationg sets in, a small increase in voltage will result in a large increase in current and increased buzz or hum as well.
Reducing voltage to a transformer is not a problem unless the load will then demand more current - which may result in excessive heating and failure.
In the case of synchronous motors, there is nothing you can do - the speed is determined by construction and the gear ratios.
Those that are entirely electronic may have a switch or jumper (probably inside) to select the AC frequency - 50 or 60 Hz.
Many devices use an internal quartz crystal for the clock or timer and will not be affected at all. Devices like VCRs may or may not use the power line for timing. Of course, battery operated equipment will always use an internal quartz crystal as there is no connection to the power line.
However, note different TV standards will likely result in your TV and VCR working together but not able to receive or record broadcasts or cable.
Some equipment explicitly states the acceptable voltage and frequency range. In the case of a universal power adapter, this may range from 90 to 260 V DC or AC up to 400 Hz - or more.
Modern TVs do not care about power line frequency at all as they do not have any power transformer. Really old sets may run into core saturation problems but these are mostly dead by now.
Note: the video frame rate is not tied to the power line in any way. Therefore, a U.S. TV with a 60 Hz (actually 59.94 Hz) frame rate will work just fine in a country with 50 Hz power assuming the voltage is correct. However, it will not be compatible with broadcast or cable or likely a VCR purchased in that country - see below.
VCRs may use a small power transformer in the power supply so changing from 60 Hz to 50 Hz may result in overheating though probably not likely.
However, taking a VCR and TV from the U.S. to a European country, for example, may not be worth it. They will work fine with each-other (as long as the voltage is proper) but the video standards in foreign countries are not compatible with those in the U.S. Therefore, it may be better to buy new equipment overseas unless you are taking your prized collection of videos and will obtain other equpiment to deal with broadcast and cable. There are also services for copying video cassettes from one standard to another and these may represent an alternative to lugging the equipment with you.
Clocks using the power line to drive an electronic display may have a jumper to select 50 or 60 Hz. Even this may not be worth the effort to locate as it is likely not going to be labeled.
Where the frequency isn't the same, the current through the lamp may differ, most likely too high in going from 60 Hz to 50 Hz, too low the opposite way. If the current is too high, there could be shortened lamp life at the very least or even a serious fire hazard. If the current is too low, the lamp may not remain on in a stable manner, flickering, or constantly restarting. Initial starting could also be affected.
If they use electronic ballasts, the frequency probably won't matter. Some "universal" types, can accommodate an input voltage from 90 to 250 VAC up to 400 Hz or even DC.
In all cases, it is best to consult with the manufacturer if the product label doesn't explicitly indicate "50/60 Hz" operation. When in doubt, leave them behind since there is really no way to be sure of the safety issues.
Except for the tuner or tuner portion of the receiver, the only issue is power. Audio equipment almost always uses a transformer type power supply so the comments in the previous chapters should apply. A voltage converter will be needed to go from 110 VAC to 220 VAC or vice-versa. In this case, it really should be a true transformer. Anything else is quite likely to introduce unaccceptibel interference in the form of a hum or buzz even if it doesn't result in any damage to the equipment. As noted, going from 60 Hz to 50 Hz could intruduce problems of transformer core saturation in marginally designed equipemnt as well.
Line frequency doesn't affect the performance of a microwave that much (perhaps a 5 percent increase in cooking power from 50 Hz to 60 Hz) but the timer and clock will likely be affected and may not be easily adjusted - not at all in the case of a mechanical timer though there may be a jumper for an electronic timer. However, the turntable and cooling fan motors will also be affected and attempting to account for all the variations is probably just not worth it!
Similary, monitors may use a switch or jumper to select voltage or have a universal power supply.
PCs and monitors do not use the line frequency for anything - not even the real time clock.
Some may have universal power supplies - check your instruction manual!
For anything other than a simple heating appliance (see below) that uses a lot of power, my advise would be to sell them and buy new when you get there. For example, to power a microwave oven would require a 2kVA step down (U.S. to Europe) transformer. This would weigh about 50 pounds and likely cost almost as much as a new oven.
Note that some places like Japan may even have varying power specifications in different parts of the country. Isolated areas such as islands may have their own power generators with very erratic and voltage and frequency. The following discussion assumes power from a large (national) grid.
There are several considerations:
For electronic equipment like CD players and such, you will need a small step down transformer and then the only consideration power-wise is the frequency. In most cases the equipment should be fine - the power transformers will be running a little closer to saturation but it is likely they are designed with enough margin to handle this. Not too much electronic equipment uses the line frequency as a reference for anything anymore (i.e., cassette deck motors are DC).
Of course, your line operated clock will run slow, the radio stations are tuned to different frequencies, TV is incompatible, phone equipment may have problems, etc.
Some equipment like PCs and monitors may have jumpers or have universal autoselecting power supplies - you would have to check your equipment or with the manufacturer(s). Laptop computer, portable printer, and camcorder AC adapter/chargers are often of this type. They are switching power supplies that will automatically run on anywhere from 90-240 VAC, 50-400 Hz (and probably DC as well).
Warning: those inexpensive power convertors sold for international travel that weigh almost nothing and claim to handle over a kilowatt are not intended and will not work with (meaning they will damage or destroy) many electronic devices. They use diodes and/or thyristors and do not cut the voltage in half, only the heating effect. The peak voltage may still approach that for 220 VAC resulting in way too much voltage on the input and nasty problems with transformer core saturation. For a waffle iron they may be ok but not a microwave oven or stereo system. I also have serious doubts about their overall long term reliability and fire safety aspects of these inexpensive devices..
For small low power appliances, a compact 50 W transformer will work fine but would be rather inconvenient to move from appliance to appliance or outlet to outlet. Where an AC adapter is used, 220 V versions are probably available to power the appliance directly.
As noted, the transformer required for a high power heating appliance is likely to cost more than the appliance so unless one of the inexpensive convertors (see above) is used, this may not pay.
First, check your user's manual (which you of course have saved in a known location). It may provide specific instructions and/or restrictions.
Most component type CD players use a simple power supply - a power transformer followed by rectification, filter capacitors, and linear regulators. These will usually only require a small step up or step down transformer to operate on a different voltage. Since power requirements are minimal, even a 50 VA transformers should be fine. WARNING: never attempt to use one of those cheap lightweight power adapters that are not true transformers to go from 220 V to 110 V as they are designed only for heating appliances. They will smoke your CD player (or other equipment not designed to handle 220 V to 240 V input).
Some CD players may have dual voltage power transformers which can be easily rewired for the required voltage change or may even have a selector switch on the rear panel or internally.
The frequency difference - 50 or 60 Hz should not be a problem as nothing in a CD player uses this as a timing reference. The only slight concern would be using a CD player specified for 60 Hz on 50 Hz power - the transformer core may saturate and overheat - possibly blowing the internal fuse. However, I don't really think problems are likely.
For portable CD players, if your wall adapter does not have a voltage selector switch, obtain one that is rated for your local line voltage or use a suitable transformer with the one you have. As with power transformers, a frequency difference may cause a problem but this is not likely.
Furthermore, for microwave ovens in particular, line frequency may make a difference. Due to the way the high voltage power supply works in a microwave oven, the HV capacitor is in series with the magnetron and thus its impedance - which depends on line frequency - affects output power.
High voltage transformer core saturation may also be a problem. Even with no load, these may run hot even at the correct line frequency of 60 Hz. So going to 50 Hz would make it worse - perhaps terminally - though this is not likely.
"I have the following question for you specialists:Neither would I.
Can I buy a TV in any west-european country and use it in any other west European country? For example, buying a TV in the Netherlands and use it in Greece or buying in France and using in England.
Any help would be appreciated as I do not really trust the sale people at the store."
Along with the multiple audio/video formats, there may be differences in channel frequency assignments between the various countries.
Channel 5 in country X may not be on the same actual frequency as Channel 5 in country Y or Z. The channel spacings or modulation may also be different.
(From: Phil Nichols (firstname.lastname@example.org).)
Plus, in different countries the audio signal can be transmitted at a different frequency relative to the vision signal. Great! Perfect picture, no sound!
I believe most continental European countries use PAL B (narrow vision bandwidth; sound carrier 5.5MHz higher than vision carrier), whereas the UK and Ireland use PAL I (wider vision bandwidth; sound carrier 6MHz higher than vision carrier).
The wisest thing is to decide which countries you are most likely to want to visit with your TV, find out what transmission system they use, then go looking for a TV which can use that/those system(s).
Almost all TVs in west Europe are compatible (PAL-B/G), except Britain (PAL-I) and France (SECAM-L). Greece is also using SECAM, but on very few channels and not all the time.
(From: Wolfgang Schwanke (email@example.com).)
This is correct, but maybe not the whole story.
There are differences in the broadcast bands used. At least Italy uses different channel allocations than the rest of the PAL-B/G crowd. Germany uses frequencies on cable that are unused elsewhere, which only special tuners can get. Also, there are different methods for transmitting stereo sound (NICAM vs. analogue).
New TVs nowadays (sold in Europe anyway) are often all-world-standard all-frequency-bands, because it's easier for the manufacturer to make a "one for all" set instead of having so many different designs for every country. But don't rely on it.
(From Jeroen Stessen (Jeroen.Stessen@philips.com).)
Oh boy, here goes another long story:
PAL-plus is an attempt to extend the life-cycle of terrestrial PAL transmissions by including compatible wide-screen (16:9) transmissions. It is an advanced variant of the letterbox format, this means that when you receive a PAL-plus widescreen program on an older 4:3 receiver you will see black bars top and bottom. It was originally developed in Germany (university of Dortmund in cooperation with German terrestrial broadcasters and some setmakers). Later a large consortium of European and Japanese setmakers took over and finished the job. Strangely, the German broadcasters seem to use PAL-plus only very rarely.
The PAL-plus standard comprises three extensions to the PAL-standard:
PAL-plus may also be combined with teletext, ghost cancellation reference, digital Nicam stereo, VPS, PDC and what-you-have more. Theoretically it can be broadcast over a satellite channel too, but it was not designed for that and some aspects of a satellite channel do indeed give interesting technical problems.
There are also sets marketed as "PAL-plus compatible". These are mostly widescreen sets without any PAL-plus processing at all, but they allow switching of the display format between 4:3 and 16:9. They may well do that automatically, based on the signalling bits.
There are 2 methods for displaying a 4:3 letterboxed signal on a 16:9 display, without using the PAL-plus helper lines:
And there are 4 methods for displaying a regular 4:3 signal on a 16:9 display (regular PAL, has nothing to do with PAL-plus):
Interesting, ain't it ?
(From: Allan Mounteney (firstname.lastname@example.org).)
RE: Is there a TV set that covers international standards?
The answer is YES.
Reason I know is that I was with a company that made computers with TV-OUT for world wide use and wanted something that could show that the TV Out worked for various countries.
This ONE and ONLY one we could find Three years ago came from Germany and covered PAL, SECAM and the American NTSC systems and came with a note that said from the time of making/selling that set it would not work in just one small country in South America. All features (including audio) were adjustable from the front panel menu and it was a Grundig 17" job. I am advised that there is a load of others on the market now.
The company who seemed to know all about these international sets and gave us good service at that time was Andrew McCulloch Ltd in Cambridge UK. Phone: 44(0)1223-351825
(From: Mark Zenier (email@example.com).)
A book, "The World Radio TV Handbook" published by Billboard that covers TV, along with where all the world's shortwave radio transmitters are, and what sort of power comes out of the wall plug all around the world. It has a new edition each year and costs around $25 to $30.
There will be two primary windings. Each of these may also have additional taps to accommodate various slight variations in input voltage.
For the U.S. (110 VAC), the two primary windings will be wired in parallel. For overseas (220 VAC) operation, they will be wired in series. When switching from one to the other make sure you get the phases of the two windings correct - otherwise you will have a short circuit! It is best to test with a Variac so you can bring up the voltage gradually and catch your mistakes before anything smokes.
An multimeter on the lowest resistance scale should permit you to determine the internal arrangement of any taps.
With any luck, the transformer wiring will even be labeled on the case!
A three-phase motor will run on single-phase power once started - but at somewhat reduced output power (horsepower). The very simple approach (compared to complete conversion) is to just provide a means for starting. The motor will then run at the correct speed (assuming the line frequency is the same) but will not be able to develop full torque before stalling. Actually converting single-phase to three-phase will likely be more expensive than replacing the motor.
There is some info at the Building a Phase Converter site.
Until recently voltage in the UK was 240 VAC nominal, +- 6%. Voltage in most of the rest of Europe was 220 VAC. A few years ago voltages throughout Europe were harmonized to 230 VAC. This caused very little disruption; no change to power stations or distribution systems, no equipment problems caused by the change.
Why so trouble-free?
It was a politicians' change: Voltage didn't change at all (at least in the UK). The permissible voltage in the UK used to be between 226V and 253V (240+/-6%). It is now 230V -6% +10%; i.e., anything between 216V and 253V. The actual voltage is exactly what it always was, it's just called 230V. Presumably as power stations and distribution equipment age and are replaced the actual voltage will decrease; but I have certainly measured the maximum permissible 253V in June 2000.
-- end V1.12 --