How does 50hz motor differ from 60hz motor?

"Sanjay" schreef in bericht news: snipped-for-privacy@posting.google.com...

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

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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)

-- Myron Samila Toronto, ON Canada Samila Racing http://204.101.251.229/myronx19

"Myron Samila" schreef in bericht news:2fjGb.10216$d% snipped-for-privacy@news20.bellglobal.com...

phase induction

can use a

1phase 220V, or

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. 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

coal

the

power of

lower

have

220V/60Hz

motor

other

construction

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single

120V,

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

50Hz

so

The

with

of

controling

you

not

The

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.

single

120V,

motors,

50Hz

so

The

with

of

controling

you

not

The

Likely "shaded pole" where they effectively build in an inductor to change the effective phase of the 2nd pole. Frequently used in applications that need little torque (like clocks, small fans, etc.) External capacitors more likely to be seen in applications where they need some actual power out of the motor for moving things.

"Yuuper" schreef in bericht news: snipped-for-privacy@corp.supernews.com...

Hz

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

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the

ceiling

three

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

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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.

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.

-- Myron Samila Toronto, ON Canada Samila Racing http://204.101.251.229/myronx19

Maybe in a trailer park, or an older subdivision, but I have been in a number of homes with three phase power for the air conditioning, commercial grade kitchen equipment, and some had an elevator from the basement, to the first and second floors. BTW, they didn't have a personal computer in the house.

It is one thing to say that residential 3-Phase isn't common, but quite another to make a blanket statement that it doesn't exist at all.

--
Merry Christmas!

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

"Myron Samila" schreef in bericht news:xAIGb.13614$d% snipped-for-privacy@news20.bellglobal.com...

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

It's raised to 230V by now.

HOTS), the degrees

the phases are 120

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.

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.

otherwise, a 20hp

start up.

Sure.

The motor of my circular saw has coal brushes.

petrus

single

you

120V,

motors,

not

other

when

explain

50Hz

so

it

The

compared

with

time.

number of

the

controling

you

you

not

The

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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

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.

respect

of

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.

"Michael A. Terrell" schreef in bericht news: snipped-for-privacy@earthlink.net...

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

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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.

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.