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  #1  
Old Sat 17 February 2007, 23:04
fabrica
Just call me:
 
What size UPS (Uninterruptible Power Supply) would a MechMate need?

In Developing countries like our's we do encounter very frequest Mains power supply failures. This becomes a serious problem when the supply fails while we are cutting a big file.If power fails we have to start everything from the begining. I suppose a battery based inverter suppy would be the best option. Please comment.
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  #2  
Old Sat 17 February 2007, 23:15
Gerald_D
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The MechMate has the following main power consumers
1. Control computer
2. Stepper motor power supply (300 to 500VA)
3. Router or spindle (1800VA router to 4000VA spindle)

Therefore you need about a 3000VA to 5000VA UPS (3kW to 5kiloWattW) if you want to keep everything going. There is not much sense in only keeping the computer going because the machine will loose its position.

A battery system of this size will be huge.
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  #3  
Old Sun 18 February 2007, 00:59
fabrica
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But Gerald, Is their any other alternative available to guys like us other than investing on a huge battery backup (on line).
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  #4  
Old Sun 18 February 2007, 04:55
Gerald_D
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Use a 5kW Electic motor... (driven from mains supply with a diesel gen backup)
to drive a heavy flywheel...
to drive a generator....
to drive the MechMate.

If your supply company trips, it triggers the "pause" in Mach3. The flywheel gives you time for the router/spindle to come to a controlled stop.

This is all theory - I have never heard of anyone that has actually done it for a MechMate.

However, it is standard practice for communications systems on mountain tops out here. There they have the motor/flywheel/generators running with 2 tonne flywheels - when the mains power is lost, a diesel/gen starts up and feeds the motor again.
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  #5  
Old Fri 25 May 2007, 18:40
Morzapa
Just call me: Morzapa
 
Miami, Fl
United States of America
May be this could help. A power inverter with few car battery's

http://www.theinverterstore.com/the-...000w-front-250
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  #6  
Old Sun 13 April 2008, 03:46
sadik007
Just call me: Sadik 007
 
California / EU
United States of America
Hi...
consider this...
In 2007 I worked for 6m. in one of countries that have huge power problem... I think they have 2 hours on 4 hours off.. horrible..

So.. what I did... I got my hands on used UPS with no battery.. I think I got 600VA, bought new car battery with 75aH. Then simply connect Car battery directly to UPS.. UPS has to be on all the time, but had no power cuts. Use to have computer, power saving light bulb for period of 2+ hrs..

Was planing to get 1200VA version but had no need. For you application, get 1200VA good quality used UPS, I got APC... Then get 2 car battery (12V).. you should not have any problems with power... Maybe consider to get truck 24V battery, but they are expensive...

This turned out to be very cheap and simple.. Old UPS 10 euros, 50 Euros for car battery.. UPS worked for 6m without any problems.

Best of luck..
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  #7  
Old Sun 13 April 2008, 04:01
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Time to repeat post #2:

The MechMate has the following main power consumers
1. Control computer
2. Stepper motor power supply (300 to 500VA)
3. Router or spindle (1800VA router to 4000VA spindle)

Therefore you need about a 3000VA to 5000VA UPS (3kW to 5kW) if you want to keep everything going. There is not much sense in only keeping the computer going because the machine will loose its position.

A battery system of this size will be huge.
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  #8  
Old Sun 13 April 2008, 04:14
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Anyway, to run some mathematics on Sadik's numbers:

You got 2 hours out of a 75 amp.hour battery, therefore you were drawing less than 37 amps. Let's call it 30 amps because you cannot run a battery right down on an inverter. 30 Amps x 12 Volt = 360 VA for the PC and light bulb, which is okay.

However, you need to charge that battery again. Cheap battery chargers produce 5 amps. While you draw 30 Amps when the power goes out, you can only put it back at 5 Amps when the power comes back on. ie. it takes 6 times longer to charge the battery than to use it for an inverter.

Why do I know this? Because I have knocked together such a system at my company. The inverter is 1800 VA (6 computers, switchboard, fax, printer) and the charger is 20 Amp. Has 2 x 100 Amp.hr batteries.

Our country is on power rationing. Our current schedule knocks my company out for 3 periods of 2 hours each over 3 days, while my house goes out for 2 hours every Tuesday. This situation will only be solved in 3 years time, and it is going to get worse before it gets better.
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  #9  
Old Sun 13 April 2008, 04:35
sadik007
Just call me: Sadik 007
 
California / EU
United States of America
Quote:
Originally Posted by Gerald D View Post
Anyway, to run some mathematics on Sadik's numbers:

You got 2 hours out of a 75 amp.hour battery, therefore you were drawing less than 37 amps. Let's call it 30 amps because you cannot run a battery right down on an inverter. 30 Amps x 12 Volt = 360 VA for the PC and light bulb, which is okay.
I thought you were looking for simple solution, 30 minutes window so you finish the work..

If you are trying to be 100% grid independent then build this UPS + generator.. buy generator or build one your self. Simple solution would be got small engine (lawn more or so) and car alternator (truck) and connected it to car battery from UPS setup.. When UPS goes low, run the engine...

Also, seen solution.. People take small Fiat 126 engine -- spinning washing machine motor.. Also, saw one version on earth gas as well (not LPG) connected directly to house....

I don't get your point.. do you need 30 minutes of power or all day power?? You will never have all day power system with inverters. You simply need to many batteries and to long time to charge them back..


ps. UPS charge time was ok, it did not take to long to change battery, not sure how long, but never had any problems...
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  #10  
Old Sun 13 April 2008, 05:53
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Must I repeat post #2 again?

We need 3000 to 5000 VA (yes, those are thousands) to keep a MechMate working. How would you supply that for even 5 minutes without any interruption when the power goes out? (If there is an interruption, the cutter will probably snap and ruin the job).
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  #11  
Old Sun 13 April 2008, 16:35
dmoore
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I'm willing to bet for most cases, it would be hard to get a reasonable payback on the purchase of a UPS and a generator. Of course they both have to work flawless (switch over from UPS to generator), otherwise you loose your work.

David
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  #12  
Old Sun 13 April 2008, 17:18
melissa
Just call me: Melissa #83
 
Brighton (Ontario)
Canada
I agree with David. Having worked in the computer industry, I'm somewhat familiar with industrial-sized UPS units (20 kVA and up). They are certainly not inexpensive.

You also need to consider the cost of a power failure. In a business office with 100 employees, a power blip which results in an hour of downtime (by the time all critical servers are back online and happy) costs 100 man-hours.

If you're cutting a 4x8 sheet of MDF and the power fails, you've lost that workpiece, and maybe an hour or two of cutting time (my guess -- I don't have a MechMate yet ).

Is it worth spending thousands on a 5 kVA UPS, transfer switch, and generator to save 2 hours and that piece of MDF? Well, I can't answer that question for you... but it's a resounding "no" for me!

Michel
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  #13  
Old Sun 13 April 2008, 19:13
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
You could always get a generator (of fuel type you prefer) and only use that to power your cnc. That way you only run out of power when you run out of fuel. You might be suprised at how expensive it is to generate your own power. Other than that I agree with Geralds post number 2. This solution might only be warranted for the most expensive of jobs?
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  #14  
Old Mon 13 October 2008, 09:30
javeria
Just call me: Irfan #33
 
Bangalore
India
Copied from elsewhere:

............I plan to use a UPS on the PC and BOB which will then act on the estop and activate a blinker powered by the same UPS. the UPS is just 10min backup and since I am planning on LED blinker and Atom motherboard processor combo the backup will extend to around15 min.

I will set up the Estop in such a way that any power outage will trigger a estop -, I will also have a delay switch on the mains - before power enters the mains - it will go thru a Omron delay switch - this helps when in our areas there is huge variation in power and where we have external shorts where power gets on / off many times in a few second.

More over one important thing I am planning is to have a Voltmeter placed near your meter box - I have seen in my other machine with servos that any voltage drop will need changes in mach velocity settings. So better safe than sorry.

........................
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  #15  
Old Mon 13 October 2008, 10:26
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Irfan, as I queried before in this thread, what is the point of a small UPS that cannot power the spindle/router?
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  #16  
Old Mon 13 October 2008, 11:33
javeria
Just call me: Irfan #33
 
Bangalore
India
I only had the UPS to protect any crash on the computer system - so that a decent save and close procedure can be used, and also bcos its very in-expensive to have one.

with power going on -off several times it might actually help elongating the life of the computer.

I just thought I would utilize the same to show up E stop like a blinker or buzzer. - this is just a add on.

G' I think I am coming a full circle

I have to read more and more - and more!

RGDS
Irfan
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  #17  
Old Thu 23 October 2008, 12:56
raj123mehta
Just call me: raj123mehta
 
UK
United Kingdom
Quote:
Originally Posted by fabrica View Post
In Developing countries like our's we do encounter very frequest Mains power supply failures. This becomes a serious problem when the supply fails while we are cutting a big file.If power fails we have to start everything from the begining. I suppose a battery based inverter suppy would be the best option. Please comment.
you need 3000VA to 5000VA UPS for your machmate.
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  #18  
Old Thu 23 October 2008, 18:55
dragonfinder1
Just call me: Dave #49
 
Astoria, Oregon
United States of America
There used to be a company that made a 3kw ups, That ups could run full load for 14 minutes, cost nearly $4000. Now when you add the cost of a stand-by generator, with the proper switching ( auto start on power failure ) , at nearly $6000, that will buy a lot of e-machine computers. A more cost effective way to go would be to buy a ups for the computer ( a couple of a hundred dollars for a good one ) and have another new computer sitting in the office in the event it actually failed.

Dave
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