Extractor motor rpm

[Hombre]

Context:

Not that it matters at all for honey extraction, and most stuff in the UK nowadays originates in China. I seem to recall that 2800 rpm is a loaded (not free running) speed often associated with 60 c/s mains supplies.

Statement:

If operated on 50 c/s supplies then they run about 20% slower.

Not quite correct, on a 50Hz AC supply the motor will run: about 17% slower than on a 60Hz supply.
Conversely the 60Hz supply will make the motor run about 20% faster than on a 50Hz supply.

Semantics, and we probably all know what you meant, but in the interests of more approximate accuracy (I love irony); i've seen accounts/sales departments make price increase errors and then seek to reduce the new price by the same percentage, in the vain expectation that they would arrive at the original price. Only to be sadly still up the creek.

Norton, most people accepted that frequency was measured in Hz (previously c/s) sometime before 1970, although there was a lot of resistance to the new terminology in the late sixties.
The AC voltage supply in the UK is 230V, Not 240V or 250V or anything that would make the arithmetic simple of course.

Not given as criticism, but merely adjustment of the facts for conversational accuracy and something to say! by way of minor controversy.
Interested that your honey is occasionally around 12%, stiff blades needed on your butter knives in the winter then?

 

[Norton]

Hello,
JUst to add to the confusion they say that the voltage here is 220-240v. As I said, I am not an electrician.
Best regards
Norton

 

[JCBrum]

Not quite correct, on a 50Hz AC supply the motor will run: about 17% slower than on a 60Hz supply.

In a perfect world maybe, which is run by accountants, or shopkeepers , but this is the real world, and needs realistic approximations.

Firstly the motors in question are often called "synchronous" motors. This is because the 'mains' supply appears to rotate 50 times per second. This is very closely controlled at the generating station.

Consequentially to "synchronise" the motor also needs to rotate at 50 c/s. In the real world this never happens, and the difference is called the "slip speed", which varies with load, but practical engineers assume a figure of about 3%. Hence 17% +3% = 20%. I hope this helps. (It's actually 16.6666 % + any figure you like ! so book-keepers maths is not very useful here

Semantics, and we probably all know what you meant

Definitely, and probably not !

but in the interests of more approximate accuracy (I love irony); i've seen accounts/sales departments make price increase errors and then seek to reduce the new price by the same percentage, in the vain expectation that they would arrive at the original price. Only to be sadly still up the creek.

Possibly so, but accountancy and engineering are quite differing disciplines and I would be in fear of my life if I had to depend on a machine designed and made by an accountant.

Norton, most people accepted that frequency was measured in Hz (previously c/s) sometime before 1970, although there was a lot of resistance to the new terminology in the late sixties.
The AC voltage supply in the UK is 230V, Not 240V or 250V or anything that would make the arithmetic simple of course.

Ha Ha, You've not measured it much then ? It actually varies quite a lot according to Region, time of day, and Season. The actual figure is not very important but 230v is a fair intended average.

Not given as criticism, but merely adjustment of the facts for conversational accuracy and something to say! by way of minor controversy.

Taken in the same spirit, but I think by now, Veg is beyond help

Interested that your honey is occasionally around 12%, stiff blades needed on your butter knives in the winter then?

Stiff Blades, to you too !

JC.

 

[VEG]

JC what hombre said made no difference to me whatsoever lol as i didnt understand a word of it.

 

[JCBrum]

JC what hombre said made no difference to me whatsoever lol as i didnt understand a word of it.

Ha Ha, I thought so

 

[VEG]

 

[Black Comb]

This thread seems to just run and run...

 

[JCBrum]

It's motoring on ....

 

[m100]

The AC voltage supply in the UK is 230V, Not 240V or 250V or anything that would make the arithmetic simple of course.

It is nominally 230v, harmonised under an EU directive to be the same as everywhere else in the EU but with a permitted variation of +/- 10% so 207v to 253v (in the UK until last year the permitted range was -6% +10%)

230v is what you would use in calculations, but you'll find that the measured voltage is usually closer to 240v and often closer to 250v as that usually means that consumer loads will draw more current and you will get a larger electricity bill meaning more profit for the evil electricity companies owned by Johnny Foreigner.

 

[hedgerow pete]

after reading all the way through this thread i have come to the conclusion that an electric drill, fixed speed extractor or a dc motor ( 24 volt dc windscreen wiper motor of a lorry 80 watt) with a last attempt at using the childs 24 volt electric scooter plus all its ready to use speed controlers is best

as for the other conclusions i have come to
jcb has far to much time on his hands
i have missed the frissbe ass moment, damm
veg is going to get powered up somehow
and lastly only a very very sad man would read this whole thread

 

[VEG]

mmmm but what rpm are they? lol

 

[OXFORDBEE]

Apparently if you have solid plastic combs and spin them at 1,000 to 2,000 rpm the honey comes through the beeswax cappings without the need to uncap the combs before extraction...

Allegedly at these high speeds even crystallised honey can be removed from the combs...

 

[Norton]

and lastly only a very very sad man would read this whole thread

I give up - I really do - here we are talking about RPMs, Spitfires, Me262, voltages and other such interesting things and everything else the krauts can produce and you come along with Seasonal Affected Disorder postings.............

 

[plumber]

still going round

if you are thinking of useing a drill have alook at a paddle mixer that is used for mixing plaster. Screwfix cat' 5 different types speeds 0 to750 rpm .5 inch chuck £80 up to £250. lock on switch dial up speed metal gearbox all industrial tools. find away to clamp it down job done. they have soft start as well.

Screwwfix.com page 914

 

[JCBrum]

Plumber, have a look at post #60, and see whether you approve.

 

[Norton]

It is all too much for my non-electric brain - I think I'm gonna blow a fuse!!!!!!!!!!!!!

 

[plumber]

missed that completly, mixing plaster today and light dawned on me

thought I had read all the posts

now that the power unit has been sus'd what about a tank ? HDPE OR S/Steel
and home made cage

 

[BKF Admin]

Apparently if you have solid plastic combs and spin them at 1,000 to 2,000 rpm the honey comes through the beeswax cappings without the need to uncap the combs before extraction...

Allegedly at these high speeds even crystallised honey can be removed from the combs...

I have this picture in my head of a disaster area.

 

[JCBrum]

I have this picture in my head of a disaster area.

The allegedly 'famous last words of the Lord Mayor of Hiroshima' spring to mind ........

" What the f*** was THAT ? "


JC.

 

[JCBrum]

without wishing in any way to diminish the awful events of 1945, which brought an end to global war, and allegedly saved an even greater continuing loss of life.