How does 50hz motor differ from 60hz motor?

[Sanjay]

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

 

[petrus bitbyter]

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

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

 

[Myron Samila]

They use three phases and their number of

revolutions depends on the number of coils in their stator and on the
frequency.

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)

 

[petrus bitbyter]

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)

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

 

[Thinker]

single
phase induction 120V,
1phase 220V, or motors,
US uses 480V I

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.

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

 

[petrus bitbyter]

So how about my electric wall clock? I believe it has a single phase 60 Hz
synchronous induction motor. It has no capacitors. It will certainly run
slower and be totally useless if used with 50 Hz power.

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

 

[petrus bitbyter]

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!

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

 

[Myron Samila]

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.

 

[Myron Samila]

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.

 

[petrus bitbyter]

The voltage isn't raised between both phases accordingly.

No? It was about 380V and now its nearly 400V.

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

It's raised to 230V by now.

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.

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.

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

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.

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.
Sure.


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

The motor of my circular saw has coal brushes.

petrus

 

[Mjolinor]

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.

 

[Mjolinor]

No, Petrus. A typical North American home uses 240 VAC center tapped
single phase with the center tap grounded. Low power circuits are 120
VAC, while larger items are on dedicated 240 VAC circuits. If three
phase passes your house, it is to allow the utility company to select a
single phase for load balancing.

When I was a kid I grew up in a subdivision of identical houses. The
main road had three phase, with a single pair of wires going down each
street, and a power transformer for every four houses.

These days, you may find only one or two homes per transformer to
keep distribution problems from affecting as many homes. If a branch
breaks a wire and shorts a single transformer, it only affects a couple
homes. If a transformer goes bad a smaller crew can replace it, and if
a new home is built, it is easier to supply the extra electricity.

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

 

[petrus bitbyter]

No, Petrus. A typical North American home uses 240 VAC center tapped
single phase with the center tap grounded. Low power circuits are 120
VAC, while larger items are on dedicated 240 VAC circuits. If three
phase passes your house, it is to allow the utility company to select a
single phase for load balancing.

When I was a kid I grew up in a subdivision of identical houses. The
main road had three phase, with a single pair of wires going down each
street, and a power transformer for every four houses.

These days, you may find only one or two homes per transformer to
keep distribution problems from affecting as many homes. If a branch
breaks a wire and shorts a single transformer, it only affects a couple
homes. If a transformer goes bad a smaller crew can replace it, and if
a new home is built, it is easier to supply the extra electricity.


--
Merry Christmas!

Take care, and God bless.
Michael A. Terrell
Central Florida

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

 

[Mjolinor]

I readily admit its not common, but there is a home near Mt Dora,
Florida with three phase power. They also have a large Onan three phase
electric start generator. I worked on several systems there, including
cleaning the control wiring on the generator. It was owned by the family
who owned and ran Sullivan's nurseries, and Sullivan's Trailway Lounge
in Orlando. The property had three, three phase feeds. One for the main
house, and two for several eight inch wells. They also had a pair of
large diesel powered water pumps to provide water to the nursery, if the
power was out very long. No, the office wasn't in the main house. It was
on the feed to the main well pumps, quite a ways from the house. The
property was probably over 3000 acres. They had bought a number of farms
around their large home to build their nursery over the years, and they
were in the process of turning it into a golf course and a large
subdivision when the owner died.

There are other large homes in what was rural areas with three phase
at the street, and they have it in their homes. There is no problem
getting three phase service in Florida, if it passes your property. Its
up to the utility and the state regulations to decide if you can have
three phase. I can't get it here at home because this small subdivision
is on a single phase. It doesn't matter, because I don't have anything a
small three phase converter couldn't handle. The mother of a friend of
mine was a local office manager for Florida Power. She could make a
couple calls and get any answer you needed. Some were rather
interesting, compared to the way they ran things in SW Ohio.
--
Merry Christmas!

Take care, and God bless.
Michael A. Terrell
Central Florida

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.

 

[petrus bitbyter]

In 50 years up and down the west coast of the US, I have
NEVER seen 3-phase power in a residence. Even in large
multi-million dollar houses, they have conventional 240V
with grounded center-tap (120V branch circuits). Only 3-
phase I've seen was for shop/farm power.

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

 

[Myron Samila]

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.

 

[Myron Samila]

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.

 

[petrus bitbyter]

...

Of course, same here (and likely most places). But I thought
we were discussing what was actually WIRED INTO THE
HOUSE. Although it is not necessarily common deep
within large residential areas to see all three phases going
down the street past your home. You can save money by not
distributing what you will likely never need in the forseeable
future.

Reminds me of the story of the power utility guy giving
his friend directions to his house. Went something like...
"Follow the 38K feeder to the fourth stepdown, turn
left and follow the 19K branch to the second crossover,
turn right, two blocks past the isolation switch, and I live
at the third transformer."

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

 

[Jim Thompson]

[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

 

[Tomi Holger Engdahl]

Most countries in western Europe used 220V for a long time. These days it
has been raised to 230V.

This is true.

It is said that it eventualy will become 240V.

To my knowledge there is no plans for the voltage to
become 240V in Europe. 230V is the standardized voltage
throughout Europe.

The voltage between two phases raised accordingly.

Yes. 230V from neutral to phase and 400V between phases nowadays.