Running 3ph tools....the cost.....

[Darren]

I was reading on "the other site" about some chap explaining the pros and cons of different ways to run 3ph tools on a single phase supply.

It was very long winded thorough, and he totally dismissed Rotary Converters on the grounds of running costs....

Now to my mind there is nothing to worry about as 3 phase motors are quite a bit more efficient than single phase motors. OK you have to add the Rotary costs but together you shouldn't see much of a difference over a single phase motor of the same power output.

This chap was claiming his rotary and machine was costing him about £5.00 an hour to run and as a result he sold his rotary and bought a VFD which he claims is much cheaper to run.


Rubbish, total rubbish. You'll only use what power the motor/s need to run smoothly....At £5.00 an hour I'd sell my machines in an instant....


So I decided to measure my stuff to see what is really going on, like I had nothing better to do but I was now intrigued...

So here's some "measured" facts.....

My Rotary converter, 2.2Kw or 3HP

Mill, 1.5HP 2.5A


Rotary on it's own uses 330W/1.88A

Rotary and mill with the transverse motor also running (2 motors) 720W/5.33A
If you minus the rotary that makes the mill 390W/3.45

At a total of 720W that's around £0.10 an hour.....so 10hrs mill usage will cost me £1.00

Hardly break the bank at that rate would it....

I hope you find that interesting.....

[John Stevenson]

But how much does the 240 volt to 440 v brick use ?

Damn hush my mouth shouldn't have mentioned that , 950 brownie points lost.

John S.

[Darren]

 

That's inc with the calcs for the converter...... 

[CrewCab]

I hope you find that interesting.....  

Very ............. actually, I was wondering earlier ............ while the mill was skimming a long piece of Cast Iron and I had nothing to do except watch the kettle boil .......... again  ....... dam thing is almost self sufficient 


but, yes that's good to know, ................ I didn't think the overall consumption would be a great deal but it's nice to have it confirmed 

I will print this out and go see the Chief Financial Officer (Mrs CC) .............. and once again,       explain that the bloomin 2 KW tumble drier, on 24/7 is the problem 

CC

[Darren]

I will print this out and go see the Chief Financial Officer (Mrs CC) .............. and once again,      explain that the bloomin 2 KW tumble drier, on 24/7 is the problem  

CC

I had to laugh, yes I get that very same problem here too.......

"constantly get asked how much "those machines" cost to run.....
My reply....less than the telly......which I don't watch....

Damned thing is on all day, my mill,lathe and everything else maybe 8hrs a week of actual running time....maybe, and that's pushing it....


Do as I did, tell her to go and get one of those digital plug in things that tells you everything you need to know and then some.....
Boy did she have a shock.....shut her up though.....

[CrewCab]

Unfortunately Mrs CC seems to have an addiction to using the washing machine ............. and subsequently the Tumble Drier  ............. OK, she puts up with my hobbies ............ so ...............   

CC 

[John Stevenson]

Unfortunately Mrs CC seems to have an addiction to using the washing machine ............. and subsequently the Tumble Drier  ............. OK,

CC 

Buy an elliptic dog and throw it in the bath with the washing....................

John s.

[bogstandard]

Buy an elliptic dog and throw it in the bath with the washing....................

Never seen an oval dog before, sure you don't mean epileptic? 

But getting back to the point.

I received off British Gas (free of charge) one of those radio monitors that tells you how much overall power you are using, and you can then turn on/off appliances just to see how much they are really costing you. It is very eye opening.

Very similar to this

http://www.currentcost.com/product-theclassic.html

I have done a study on my workshop, and for medium usage, say four or five hours a day, every day, my shop uses between 20 and 25 squid per month. I cannot be more exact as some machines use more power than others, but this is what I came up with, erring towards the low side.

To me, a fiver a week is nothing compared to other forms of entertainment, a couple of pints of beer, a pizza, or quadruple it and it gives you a night out at a cheap restaurant for one.

But I am a little frugal in my shop, I will turn off one major machine completely before doing something on another major machine (lathe, mill, grinder, buffing machine, power hacksaw etc), even if it means turning it back on again in a few minutes. If I return to the house, I will throw all the main ring trips in the workshop, and turn them back on when I return. Every little helps to keep the costs down.


Bogs

[kvom]

Your and my rotaries will never be running loaded, so never actually delivering rated HP.  So cost of running is pretty minimal.  My shop, during the colder months, cost about $50/mo. and that included the radiant heating startup.

[Darren]

Quite right, and I'd imagine quite a few of our machines would never need to produce the motors rated horse power either.

3hp, mill.....there must be a reason...but what for...?

[John Stevenson]

My big TOS lathe has a 10 hp 3 phase motor on it running off genuine 3 phase, Most of the time it's ticking over just licking bit out of big pieces but very occasionally it has to grunt.

A while ago I was belting a 3 1/2" pilot drill though a lump of 5" bar from a dead start just to get a hole for the boring bar to fit and this bastich just upp and stalled.

What ?? all that power and the bastich has the nerve to stop on me. Felt like writing to the women's column and asking "Dear aunty Jane do I need more horsepower or is the drill blunt ?"

Truth of the matter was the 6,878 drive belts were slack....................

John s.

[Darren]

3 1/2" pilot drill......so ok, at what size is it no longer classed as a pilot.......

Words mean a notin.......

ps, I'm not really looking for a reply, but 10hp for such a small drill......

[John Stevenson]

3 5/8".................................

John S.