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How does 50hz motor differ from 60hz motor?

Discussion in 'Misc Electronics' started by Sanjay, Dec 24, 2003.

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  1. Sanjay

    Sanjay Guest

    Can anyone please explin to me how will a 50hz motor differ compared
    to 60hz motor on the way it operates and on the construction.

    thank you,
    sanjay
     
  2. Sanjay,

    A huge amount of small motors - generaly speaking the ones equiped with coal
    brushes - don't care. You see them rated for 50-60Hz most of the time.

    Inductionmotors are different. They use three phases and their number of
    revolutions depends on the number of coils in their stator and on the
    frequency. You can even control the number of revolutions by controling the
    frequency. But there's a drawback. When you rise the frequency, the power of
    the motor is reduced. So you have to rise the voltage as well. If you lower
    the frequency the coils get saturated and the motor becomes hot. So you have
    to lower the voltage as well. So if you run a 220V/50Hz motor on 220V/60Hz
    the number of rotations is too high and the voltage is too low. The motor
    will run faster but cannot deliver the full power. If you do it the other
    way around, the motor will be too slow and become too hot. As you do not
    want to change the mains voltage you have to adjust for it at construction
    time. This can be done by changing the number of turns of the coils. The
    more turns, the higher the voltage it can handle.

    So a 220V/60Hz motor has less coils and less turns per coil then its
    220V/50Hz counterpart.

    petrus
     
  3. Myron Samila

    Myron Samila Guest

    They use three phases and their number of
    What do you mean all induction motors use three phases? There are single phase induction
    motors out there.

    If there is ever a problem with using a 50hz motor in a 60hz region, you can use a
    frequency converter - either of solid state or motor driven. 1phase 120V, 1phase 220V, or
    3 phase 208V or higher (we use 600V in Canada for most industrial motors, US uses 480V I
    believe)
     
  4. The majority of induction motors use three phases, although you would not
    find many of them in common households. Most of the one phase motors use
    large capacitors to simulate the three phases. I found most of them in
    washing machines. I consider them three phase motors. There are some other
    possibilities using extra coils (inside the motor) and/or capacitors.
    Sometimes they are used only to start the motor and are switched off when
    the motor runs. I did not want to go too deep into this details to explain
    the difference between a 50Hz and 60Hz motor.

    Lately someone in another (not an english) newsgroup bought a piece of 50Hz
    equipment in Europe and sent it to America. It did not function too well so
    he needed a converter. Which was more expensive then the equipment....

    Most countries in western Europe used 220V for a long time. These days it
    has been raised to 230V. It is said that it eventualy will become 240V. The
    voltage between two phases raised accordingly.

    petrus
     
  5. Thinker

    Thinker Guest


    Only a person with absolutely no electrical knowledge would call motors
    such
    as you are referring to as 3 phase motors. You obviously have no idea of the
    purpose of the capacitor in these motors! Search for "split-phase motor"
    and after
    you do a bit of research come back and explain why you think all induction
    motors
    are 3 phase. I have many single phase induction motors in my house. 2 in
    the furnace,
    water pump,refrigerator, deep freeze,washing machine, dryer,several ceiling
    fans. All
    of them are induction motors and NONE of them can be remotely called a three
    phase
    motor. The ONLY 3 phase motors in a home in North America are the drive
    motors
    in you computer disks!









    There are some other
     
  6. As you said your wall clock has a synchronous motor. I was speaking -
    although not explicitly I have to admit - about asynchronous brushless
    (induction) motors. Remember, I tried to explain the difference between 50Hz
    and 60Hz motors.

    petrus
     
  7. 1. You know very little about my knowledge.
    2. I wrote the majority of induction motors to be 3 phase which may be wrong
    because
    3. You have much more motors in your house then I have.
    4. I don't live in North America.
    5. I don't feel like to have a fruitless discussion about this.
    6. As you know so much about electricity, explain the difference between a
    50Hz and a 60Hz motor to the OP. (Not to me.)

    petrus
     
  8. Myron Samila

    Myron Samila Guest

    The voltage isn't raised between both phases accordingly.

    In all of Europe, 220V is on the HOT side, 0V is on the Neutral side.

    We make (In Canada) 220V or 208V by using SINGLE phase 220V (using 2 HOTS), the degrees
    they are apart makes a potential of 220V, in three phase, you get 208V, the phases are 120
    degrees apart.

    Capacitors are used in starting motors. They do not really simulate 3 phases.

    3 Phase motors use POWER FACTOR capacitors as well to aid starting, otherwise, a 20hp
    screwdrive air compressor would draw massive amounts of current during start up.

    I have a table saw, it uses a SINGLE phase induction motor.
     
  9. Myron Samila

    Myron Samila Guest

    Also wanted to mention,

    What do you mean that they use large capacitors?

    Large in uF capacity? or in size.

    Most are of large size, and oil filled, 2uF and appropriate voltage for the application
    (for single phase motors). Power factor caps, aid in starting, nothing more (they do not
    simulate 3phases)

    It is also easier to start a 3 phase motor, you can also control direction by reversing a
    phase.

    I have worked on massive beam saws that cut up to 8 sheets stacked of wood per pass (CNC
    X/Y), (Holz Her, Homag, Holzma), wild stuff. Massive motors, induction. They use current
    sensors (PLC) to measure how dull the blade is.
     
  10. No? It was about 380V and now its nearly 400V.
    It's raised to 230V by now.
    So you use two of the three phases. Each will have about 127V with respect
    to neutral. You will find a single phase 220V with respect to each other of
    course.
    Will be true most of the time. A single phase does produce a rotating field
    the way a three phase system does. So at least during startup you have to
    provide an extra "phase" which can be switched off by a centrifugal switch
    when the motor runs. But I often saw "real" three fase motors used with a
    capacitor and I ever used one myself as well.
    The motor of my circular saw has coal brushes.

    petrus
     
  11. Mjolinor

    Mjolinor Guest

    It's raised to 230V by now.

    Unless you live in the UK in which case it was lowered to 230, it was 240.
    In reality they didn't change anything they just adjusted the tolerances to
    bring it in line with mainland Europe.
     
  12. Mjolinor

    Mjolinor Guest

    This is how it is done in the US (specifically Florida FPL, I love working
    there :)), each green triangle is an MV/LV transformer and will supply about
    10 houses. The blue supply from the primary sub is three phase MV and the
    black lines joining the green triangles are MV single phase.

    http://www.dknpowerline.com/Pictures/us1.gif
     
  13. Michael,

    *That* I did not know. Thanks for the correction.

    When I was a boy we had 127V. I remember the day it all has to change to
    220V. We had to do without washing machine and vacuum cleaner for some days
    as they has to be modified.

    Some twenty years later I lived - with eight other students - in a house
    that used two 127V phases to become 220V. As only one hot was monitored by
    the kWh meter some students used (by that time old) 127V equipment to reduce
    their costs.

    Merry Christmas and a happy new year too.

    petrus
     
  14. Mjolinor

    Mjolinor Guest

    Were these three phase LV feeds? I have worked a lot at FPL and never seen
    an LV feed at three phase, in fact I have never seen a three phase 11kv /
    110-0-110 at FPL at all either in storage, training or transformer
    rebuilding yards.
     
  15. Which only shows the world to be a little bit larger then the US west coast.
    We have three phase all over the country although most common households are
    connected to one phase only. The day I need more then 5kW I can ask for
    three phase and I'll get it. They may even refuse to deliver more then 5kW
    on a single phase as it makes load balancing more difficult. So only small
    companies or offices do *not* have three phases. (That 5kW may have been
    raised lately to 6 - or 7.5kW as they try to standardise the mains over
    whole the EC.)

    petrus
     
  16. Myron Samila

    Myron Samila Guest

    Our entire residential city grid isn't even wired for 3phase here in TORONTO!! (not the
    GTA, just surrounding areas).

    The transformers on the street are 1phase 220V, there is not 3 phase power running on the
    poles, that would have a huge effect on balancing the phases.

    Comes from the step down from the transformer station as 1ph.
     
  17. Myron Samila

    Myron Samila Guest

    In Canada, we step down using a three phase isolation transformer usually stepping down
    from 600V


    Three Phase you get a potential of 208Volts between two phases
    Three Phase you get a potential of 110Volts between Ground & Hot of any phase
    Single Phase you get a potential of 220Volts between Phase A and Phase B
    Single Phase you get a potential of 120Volts between Ground & Hot of any phase

    This is assuming a step down transformer is used for regular low voltage AC requirements.

    What I meant to say about European voltage in *ALMOST* every respect is that there is a
    220V+ potential between Hot and Ground, I thought that was pretty clear. Valencia Spain
    is 230V, I was there recently working with a design team of a professional amplifier, then
    in the UK, 240V was used as the primaries and the amp had problems, They were using a 115
    O 115V transformer, it worked on 'any voltage'. Meaning, we could wire it here for 120V,
    but, we were over voltage because the primaries were wired for 115V. Same with the UK,
    across the two 115V primaries, instead of feeding 230V, they were feeding it 240V, blowing
    up components in the amp.
     
  18. Some things are really different here. I have an old radio from the fifties
    that has a voltage carousel with eight different mains voltages ranging from
    110V to 240V. That's where we came from. The mains were standardized to 220V
    over the years but there are still local exceptions. During the last few
    years the voltage was slowly raised to 230V and it is said to become 240V
    over time.

    Where I live (in the Netherlands) power production and distribution is done
    in a three phase system. For all I know there are no air lines left except
    for >100kV. So a power utility guy will get lost. Local transformers step
    down from 10kV or 25kV to 400/230V. They have to service tens to hundreds of
    houses. The power cable ends up in a house in a sealed black box. There one
    phase is selected and connected to the kWh meter via a 25A fuse. (It may be
    somewhat over 25A these days.) If you are a power user you get three phases.
    For instance, one of our neighbours has an electric cooking-range and has
    three phases. Commonly called "powercurrent". So if someone needs more then
    the usual (~5kW) power for whatever reason they only have to rearange some
    connections and replace the kWh meter for a three phase type. This way they
    can do almost all control and maintenance without digging. Digging is by far
    the most expensive part of the laying of the power grid so they want to do
    it only once.

    petrus
     
  19. Jim Thompson

    Jim Thompson Guest

    [snip]

    I had three-phase power in the first house I bought in Scottsdale,
    Arizona (in 1964).

    It was in an area bounded by 68th St. on the west, Scottsdale Rd.on
    the east, Oak St. on the south, and Thomas Rd. on the north.

    Had a nice three-phase Goettl air conditioner that purred like a
    kitten ;-)

    ...Jim Thompson
     
  20. This is true.
    To my knowledge there is no plans for the voltage to
    become 240V in Europe. 230V is the standardized voltage
    throughout Europe.
    Yes. 230V from neutral to phase and 400V between phases nowadays.
     
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