Uninterruptable Power Supply (UPS) with CNC?

j ferguson said:
There's also the computer and as someone up-thread suggested, a light bulb. So maybe for me 750 watts for five minutes would be enough with the software tweak to write present position to file for the restart. I suppose there's also nothing wrong with skipping all this except the light bulb and going back to the beginning since I'd be cutting air until i got to the place I was when the lights went out.

FWIW, the neatest UPS I ever saw was a system sold to hospitals. It had a motor with alternator windings which when land-power was on, turned a very large flywheel at a synchronous speed. There was a magnetic clutch (very big) and a Cat diesel engine which was kept warm by heating the coolant. the clutch popped on an outage and the engine started close to instantly and picked up the slight drop in flywheel rpm and now the motor generated such that the ripple in power seen in the hospital was low enough not to bother any of their equipment. it worked too.
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A No-Break. AT&T used them at their microwave relay sites in the sixties. An elegant design.
 
Some safety practices anbd battery URLS Gents, Just be safe and realize there is a maintenance cycle here that you must adhere too. I had to keep our large Lieberts in-check for about a decade. They came in every month or two. Often a battery would be pulled due to internal this or some diagnostic that. A 24V DC high current capable system is a potential is all I'm saying. Myself, I like a small battery setup w/ a generator cutover. both are a worthwhile system if you've spent days on a complex part and the wind blows down the power. I get that!

http://www.hse.gov.uk/pubns/indg139.pdf

http://www.generatorjoe.net/html/whataboutsws.html

http://www.batteryequaliser.com/products/product_battery_maintenance.htm
 
countryguy said:
Some safety practices anbd battery URLS Gents, Just be safe and realize there is a maintenance cycle here that you must adhere too. I had to keep our large Lieberts in-check for about a decade. They came in every month or two. Often a battery would be pulled due to internal this or some diagnostic that. A 24V DC high current capable system is a potential is all I'm saying. Myself, I like a small battery setup w/ a generator cutover. both are a worthwhile system if you've spent days on a complex part and the wind blows down the power. I get that!

http://www.hse.gov.uk/pubns/indg139.pdf

http://www.generatorjoe.net/html/whataboutsws.html

http://www.batteryequaliser.com/products/product_battery_maintenance.htm
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You are indeed correct, batteries are nothing to play with and they need to be used within their means and proper charge cycles. I've come to like the sealed batteries (AGM type) because they don't leak acid all over the place. When the "sealed" batteries first came out, they had some issues but the technology is improved now and they outlast most other types.

On a technical note, the current draw on a 24V battery is only 1/2 of a 12V battery. They tend to last longer because of the reduced internal current and you don't need to use triple zero (000) gauge cables to jumper several together.

FYI: Automotive batteries are not well suited for UPS systems. They prefer to be kept at full charge. Deep cycle batteries are rated for their number of charge cycles down to 20% of full charge. Usually, it's something like 800 to 1500 cycles depending on the quality/warranty on it. If you do that with an automotive battery, it will be toast after a handful of times.



Ray
 
D.C.Clark said:
I've got this one:

https://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=BX1300G&tab=documentation

It will run my Sherline 4 Axis CNC, PC and monitor for 20 minutes, long enough to finish most any job.

David Clark in Southern Maryland, USA
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This might not need saying but...
With it hooked up to the PC, use the utility program to manually check the battery periodically. Don't rely on their automatic 'self-test'.
You may also want to verify how the automatic shutdown mode is setup if the PC is tied to the Sherline at all.
I would take the 20 minutes and cut it by half to be safe. I've used these and similar ones for eons and it is hit or miss in
regards to the length of time it provides power.
I have a couple down in the store room that are less than two years old that I've pulled out of service that behaved erratically and that
I need to (someday) go over them and diagnose their problems.

The batteries - at times - start to go after only a year, just when you're counting on 20 minutes you're lucky to get 5.
Beware of the 'Asian' counterfeits when buying replacement batteries. I had one client who found a 'better' deal on the batteries
and they somehow fried the UPS.

-=-

Another possible source for commercial grade units would be the on-line liquidator auctions, especially when they're doing a data center
of a failed biz. The rack mounted UPSs used for servers and network equipment are very heavy duty. I've used those in racks powering
multiple servers. And you get the added benefit of cleaner power to your equipment.
One such site that I use to buy equipment from back in the day: http://www.go-dove.com/en/index

_Dan
 
Consumer quality UPS equipment does not produce a true sine wave output. It is possible that some things in a shop environment might be damaged or not work correctly when powered directly from such a system. Computer systems contain switching power supplies which are unaffected by the difference in the input waveform, but some other things could be. My cnc equipment would not be a problem and that is probably the case for most people's equipment. The concern is that powering an entire shop with a consumer quality UPS might have some unattended consequences.
 
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