Another Question for the sparkies

[tony]

OK so who can tell me in words of one syllabal or less what the differance

there is between a 2.2Kw single phase two pole motor and and a 2.2Kw

single phase four pole motor....

This is doing my head in...

Tony

[dirtdawg]

pm rovercare he'll know

[ladas]

OK so who can tell me in words of one syllabal or less what the differance

there is between a 2.2Kw single phase two pole motor and and a 2.2Kw

single phase four pole motor....

This is doing my head in...

Tony

As I understand it, a four pole motor will draw less current at start up, and during running. They are generally more expensive than 2 pole and have a little more torque than a 2 pole.

..........but for most people

You put 220/240v in and the thing turns !!!!!

[scarry]

Speed,i am pretty sure 2 pole does around 2800rpm,4 pole does 1440:D

6 pole.....960 approx

[ladas]

Yes I missed the most obvious - old age I guess

Have a peek at


www.unisanet.unisa.edu.au/10496/MachinesDemofont.doc (http://www.unisanet.unisa.edu.au/10496/MachinesDemofont.doc)

[TimNZ]

Speed,i am pretty sure 2 pole does around 2800rpm,4 pole does 1440:D

6 pole.....960 approx

What he said....

Tim

[tony]

thanks guys,

tony

[Slunnie]

Yes I missed the most obvious - old age I guess

Have a peek at


www.unisanet.unisa.edu.au/10496/MachinesDemofont.doc (http://www.unisanet.unisa.edu.au/10496/MachinesDemofont.doc)
According to my calculations...

The earth spins at 1/525960rpm.

So according the forumla in that link where (rps = 50 divided by the number of pole pairs) and the frequency of the power is at 50Hz and the world is some type of utopia, then there are 1,577,880,000 Polish couples in the world and so I can only assume then that the earth has 3,155,760,000 Poles. According to data from the CIA there was 38,500,696 living in Poland in July 2008... so it makes you wonder where the rest of the Poles are and what they are doing.... hmmm, sounds like a plan for world domination to me, especially considering the worlds population in Sept 2008 is meant to be 6,943,000,000 that would mean that approx 45% of the worlds population are infact Polish.

There's some food for thought!

[rovercare]

Speed,i am pretty sure 2 pole does around 2800rpm,4 pole does 1440:D

6 pole.....960 approx


What he said....

Tim

What they said:cool:

[81stubee]

In one word

"speed"

in three words

"speed and torque"

[Bytemrk]

According to my calculations...

The earth spins at 1/525960rpm.

So according the forumla in that link where (rps = 50 divided by the number of pole pairs) and the frequency of the power is at 50Hz and the world is some type of utopia, then there are 1,577,880,000 Polish couples in the world and so I can only assume then that the earth has 3,155,760,000 Poles. According to data from the CIA there was 38,500,696 living in Poland in July 2008... so it makes you wonder where the rest of the Poles are and what they are doing.... hmmm, sounds like a plan for world domination to me, especially considering the worlds population in Sept 2008 is meant to be 6,943,000,000 that would mean that approx 45% of the worlds population are infact Polish.

There's some food for thought!

Slunnie,

You obviously have way too much time to think these things through mate....:angel::p

[blitz]

A little electrical lesson, the syncronous speed of a 2 pole motor is 3000 rpm, a 4 pole 1500 rpm 6 pole 750. the reason why they dont actually spin at those rpms is because of efficiency and a bit of other technobable about a motor not producing torque if it reaches syncronous.

So to work out the efficiency of the motor all you have to do is divide the rated rpm by its syncronous rpm and times by 100 and you will have the efficiency of the motor

It's rated rpm is to do with the amount of windings inside of it, a 2 pole has 2 sets of windings and a 4 pole 4 - the 4 pole will have twice the torque of the 2 pole but it is at half the rpm, same same the 6 pole.

As far as the starting current goes, if they dont have some sort of soft start all motors draw upwards of 7 times its full load current on start up, which is called direct on line or DOL. The reason for this is more techno babble which is a motor at the point of instantanious start up is in effect a transformer with a shorted secondary winding, as it picks up rpm the secondary frequency lowers as does the current draw.

I hope that helped not made it worse:)

Blythe

[rovercare]

OK so who can tell me in words of one syllabal or less what the differance

there is between a 2.2Kw single phase two pole motor and and a 2.2Kw

single phase four pole motor....

This is doing my head in...

Tony


A little electrical lesson, the syncronous speed of a 2 pole motor is 3000 rpm, a 4 pole 1500 rpm 6 pole 750. the reason why they dont actually spin at those rpms is because of efficiency and a bit of other technobable about a motor not producing torque if it reaches syncronous.

So to work out the efficiency of the motor all you have to do is divide the rated rpm by its syncronous rpm and times by 100 and you will have the efficiency of the motor

It's rated rpm is to do with the amount of windings inside of it, a 2 pole has 2 sets of windings and a 4 pole 4 - the 4 pole will have twice the torque of the 2 pole but it is at half the rpm, same same the 6 pole.

As far as the starting current goes, if they dont have some sort of soft start all motors draw upwards of 7 times its full load current on start up, which is called direct on line or DOL. The reason for this is more techno babble which is a motor at the point of instantanious start up is in effect a transformer with a shorted secondary winding, as it picks up rpm the secondary frequency lowers as does the current draw.

I hope that helped not made it worse:)

Blythe

:Rolling::Rolling::Rolling:

[tony]

Blythe, I love it,

So if I understand correctley, the same hydraulac pump would produce more pressure connected to 4 pole 2.2kw motor than a 2 pole 2.2kw motor....

because the 4 pole has more torque and spins slower....


thanks again guys

Tony

[Pedro_The_Swift]

and if you've ever seen a BIG two pole motor start (sans soft start) you'll understand the term INSTANT acceleration,,
oh, yea,, and the ground moves a bit;)

[blitz]

Actually Tony that is a bit of a trick question, the hydralic pump will procuce it's rated pressure then it will bypass back to the oil resivour.

What you will have to do is check plate on the hydralic pump which will give the operating pressure and the flow rate. From the flow rate you can work out if it needs a 2 or 4 pole motor it will also have a kw rating on it to work out what size motor is required to run it up to full power.

Cheers Blythe

P.S. Sorry I couldnt do it in words of 1 syllable or less but I did cut it down to remove technobabble to get rid of all the complicated stuff.;)

or 2 pole fast but weak 4 pole slower but stronger :D:D:D

[scarry]

Pump curve for the two different speeds will give you an accurate way of working out what you need

Now it is all getting confusing,& more than one syllable

[rovercare]

Why not just take the rpm off the 3phase motor its replaceing;), that will tell you what rpm/pole single phase replacement you require