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Copyright © 1994-2021
Reproduction of this document in whole or in part is permitted if both of the
following conditions are satisfied:
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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.
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.
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:
Squarewave:
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.
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.
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 (in5379@wlv.ac.uk).)
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 (wolfi@berlin.snafu.de).)
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 (allan@amounten.demon.co.uk).)
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 (mzenier@netcom.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 V1.12a --
All Rights Reserved
2.There is no charge except to cover the costs of copying.
DISCLAIMER
While every effort has been made to assure that the information in this
document is accurate and complete, there is no way to guarantee that it will
apply to your particular equipment. Depending on the specific design, what
works in most cases may result in unacceptable performance, blown fuses or
tripped circuit breakers, or overheating and possible fire, damage to the
powered equipment or property.
Introduction
Scope and Purpose of this Document
The following types of questions arise quite often:
We cannot generally provide an answer based on your exact model equipment
and the specific standards in use. There are too many variations to deal
with in this sort of document. However, the information contained herein
in conjunction with the type and specifications of the equipment you own and
the power and standards in use at your destination hsould enable you to make
an informed decision.
Note that if you plan to be moving between countries with different standards,
it may pay to invest in appliances and electronic specifically designed for
multisystem operation. However, there are all sorts of definitions of
'multisystem' - not all will handle what you need so the specifications must
be checked carefully and even then, marketing departments sometimes get in
the way of truth in advertising! Again, the information in this document
and the links below should aid in this effort.
Related Information
A great deal of specific country information is available at:
including power, plug configurations, telephones, and TV standards.
Types of Conversion
You Mean it is More Than Just the Type of Plug?
Power Conversion
Video Standards Conversion
This relates to the scan rates, color encoding, and audio transmission of
the baseband video signals in use in your country.
Broadcast (and Cable) Standards
Voltage Conversion Issues and Common Types of Voltage Converters
How to Get Power for Equipment A to Work with Equipment
B
Note that in cases, the proper (or close enough) power may be available
already.
True Transformers
Autotransformers are cheaper but do not provide line isolation which may
be desirable. In general, a step-up or step-down transformer can be used
backwards to effect the opposite conversion - whether this is possible is
a construction detail. In addition, a 1:1 isolation transformer can be used
as a 1:2 (stepup) or 2:1 (stepdown) autotransformer with a VA rating twice
of what it would be when used normally.
Transformers of adequate capacity can be used with all types of equipment.
Using a Low Voltage Transformer to Increase or Reduce
Line Voltage
+------------+
| |
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
These are the low cost devices available at Radio Shack or a travel accessories
store that weigh almost nothing and have huge power ratings. They operate by
switching the power on to the load at the appropriate time during each cycle
of the AC voltage (120 or 100 times a second) resulting in approximately the
proper power being delivered to the load.
Motor Alternators
Before the development of solid state power devices, these represented an
efficient, if bulky way of converting both voltage and frequency. A
synchronous induction motor is coupled to an alternator (AC generator) on the
same shaft. By designing with the appropriate number of poles for each, this
could easily, if noisily, perform both voltage and frequency conversion.
Solid State (AC->DC->AC) Converters
These provide efficient conversion of both voltage and frequency in a light
weight compact package. The best of these generate an output nearly identical
to the power obtained from the wall socket and operate as follows:
The waveform before smoothing would look similar to the following:
|| ||
|||||| ||||||
|||||||| ||||||||
|||||||||| ||||||||||
|||||||||| ||||||||||
|||||||||| ||||||||||
|||||||||| ||||||||||
|||||||| ||||||||
|||||| ||||||
|| ||
After smoothing, the result would be very similar to a sinusoid.
_________ _________
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
| | | |
|_________| |_________|
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.
Design of High Efficiency Power Inverters
Here is a general recipe - season to taste. :)
(From: James Meyer (notjimbob@earthlink.net).)
Using this approach, you can step the input voltage up to the peak of the sine
wave that you want at the output with a decent converter that can be very
efficient and produce little waste heat.
Some Power Converter Companies
Here are a few random companies that offer power converters. I am in no
way endorsing their products and have no direct knowledge of their quality
or performance. Listed in alphabetical order.
What Appliances will be Damaged by Reduced
Voltage?
Here is a summary of various appliance types and how they are affected
by the severely reduced voltages possible during a brownout:
For appliances with more than one type of device like a microwave oven,
all factors must be considered. For this example, the oven will heat at
a reduced power level (which is safe) but the cooling fan(s) will also
run more slowly resulting in possible overheating and failure of the
magnetron. A convection space heater may overheat for similar reasons.
How Big a Difference in Voltage Before a Converter is
Needed
"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.
Effects of Improper Voltage on Resistive Loads
Effects of Improper Voltage on Constant Power
Loads
Effects of Improper Voltage on Transformer Loads
While the ideal transformer (the one they may have taught you about in EE101)
doesn't care about its actual input voltage, real transformers do. If the
voltage increases significantly above what it was designed for, the core may
saturate. This means that the magnetic field in the core cannot increase any
further and the result is to effectively short circuit the input (above a
certain voltage on the waveform). At the very least, this will result in
excessive heating and hum or buzz. The transformer may burn out if a fuse
doesn't blow first.
Effects of Improper Voltage on Motor Loads
Line Frequency (50/60 Hz) Issues
Is Frequency Conversion Needed?
The question of 50 Hz vs. 60 Hz always comes up in conjunction with
international power. However, except for equipment with induction motors
(e.g., fans, compressors), or where the line frequency is used for timing
(electric or line powered electronic clocks), the line frequency may be
irrelevant.
Effects of Improper Frequency
Equipment that Will Probably not Care About the Line
Frequency
The following are generally insensitive to frequency (50/60 Hz):
Equipment that May Work with a Different Line
Frequency
The following will probably work when going from 50 Hz power to 60 Hz power and
may work going the other way. However, transformer cores designed for 60 Hz
may saturate on 50 Hz and run hotter and/or blow internal fuses and cooling
fans will run slower - this should be checked to make sure there is no hazard:
Equipment that May have Problems on Different Line
Frequency
The following may have problems:
Recommendations for Specific Equipment
General Considerations
The sections below summarize the major issues with respect to common
appliances and consumer electronic equipment. Following these are those
which relate specifically to moving overseas or vice-versa.
Television Sets and Video Cassette Recorders
A voltage converter - preferably a true transformer or modified or true
sinewave inverter will be needed to adapt the voltage unless the unit has
a universal power supply.
Small Appliances
Specific recommendations will depend on the actual devices inside the
appliance - motors, heating elements, timers, and so forth.
Clocks
Electric clocks using a synchronous motor would require a motor or gear
transplant - not worth it. Of course, you could just live with shorter or
longer days :-).
Fluorescent Lamps
For those using iron ballasts, both voltage and frequency will be significant.
Though it may be possible to come up with a formula which incorporates both,
the best thing to do is to only use the line voltage for which the unit
was designed.
Audio Equipment
These include tuners, amplifiers, receivers, tape decks, CD players, etc.
Radios, Tuners, Receivers
In addition to the power issues (see the section: Audio
equipment, station frequencies and channel spacing differ from country
to country.
Microwave Ovens
If the voltage is different, sell where you are located and buy a new one at
your destination. The power involved would require a large, heavy, expensive
voltage converter - preferably a true transformer. It doesn't make sense for
a $150 microwave.
PCs and Laptop/Notebook Computers
Check your equipment. Most PC power supplies have a switch to select between
110 VAC and 220 VAC. Some have universal power supplies that will work within
a range of voltage between 90 and 240 V AC (up to 400 Hz) or DC. The latter
is generally true of laptop/notebook power packs.
Laser Printers
These may use a switching or transformer based power supply. This is not the
real problem. What is, is the power for the fuser - several hundred watts.
Therefore, if using a true transformer for voltage conversion, a large one
will be required.
Non-Laser Printers
These will usually use a power transformer type power supply so a voltage
converter will be needed. The frequency will only matter with respect to
transformer core saturation. Nothing in a printer depends on line frequency.
Taking Equipment Overseas (or Vice-Versa)
When does it make sense to take an appliance or piece of electronic equipment
to a country where the electric power and possibly other standards differ?
For example, going to a country with 220 VAC 50 Hz power from the U.S.:
CD Players
Fortunately, the standard for the CDs themselves is the same everywhere in
the explored universe Yes, even Australia :-). Thus, there should be no
issues of incompatibility. The differences will relate only to the power
supply.
Microwave Ovens
Microwave ovens are high power appliances. Low cost transformers or
international voltage adapters will not work. You will need a heavy
and expensive step down or step up transformer which will likely cost
as much as a new microwave oven. Sell the oven before you leave and
buy a new one at your destination.
The digital clock and timer will likely run slow or fast if the line frequency
changes as they usually use the power line for reference. Of course, this may
partially make up for your change in output power! :-)
Buying a TV in Europe
"I have the following question for you specialists:
Neither would I.
In order to enable a poor-man's PAL-plus receiver, the standard
permits using the mark "PAL-plus" if at least the vertical helper
reconstruction is included. Colour-plus is optional, so you will find
sets on the market with only half of the PAL-plus extension.
Both modes may be called "movie expand". Only when you really convert to
full-resolution widescreen will it be called "widescreen".
With both modes, the left and right edges of the picture will be stretched to
fill the left and right bars, but the aspect ratio of the centre part of the
picture will hardly be affected.
Items of Interest
TV, Shortwave, Power Worldwide
About the Vertical Scan Rate
TVs never ever used the line frequency for vertical rate. The vertical rate
is not even equal to line frequency, actually 59.94 Hz (NTSC). It was set
originally to 60 Hz to minimize the visibility of interference between the
deflection and power transformer. When NTSC added color, it changed to
59.94 Hz. And, TVs no longer have power transformers.
Determining Unknown Connections on International Power
Transformers
Most likely, you can figure this out if you can identify the input connections.
Running Three-Phase Motors on Single-Phase Power
This may be an issue if you picked up a South Bend lathe with a 10 foot bed
at a garage sale for $1 or more realistically with professional shop equipment
like large saws or planars.
A Note on Voltage in Europe
(From: Michael Salem (4ms2u$ms@michaels.demon.co.uk).)