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Author Topic: How to recover from power interuption?  (Read 11816 times)

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Re: How to recover from power interuption?
« Reply #20 on: September 15, 2010, 12:36:23 PM »
Evening all.

Been away for two days, so no followup by me. Sorry.

Ian. No. So far I am at the planning stage. This power outage has me worried so I am not spending money for the moment. How do you think using "Feedhold" will help?

The idea of accurate limited switches has my interest. Has anyone tried using "Linear variable differential transformer" LVDT techniques. These have been around from before my young days as an engineer and seem to have a lot going for them. This afternoon I made up an example and it can resolve better than anything that I have to measure with. It would be good to know if others have any experience with them.

How do I find the wiki referred to for OEM codes?

Thanks all.

Dennis

Offline Hood

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Re: How to recover from power interuption?
« Reply #21 on: September 15, 2010, 12:39:26 PM »
How do I find the wiki referred to for OEM codes?

Thanks all.

Dennis
Support tab at the top of the page.
Hood

Offline stirling

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Re: How to recover from power interuption?
« Reply #22 on: September 16, 2010, 05:15:45 AM »
How do you think using "Feedhold" will help?
Well that was the point of my question really. I think there's quite a bit more to it than JUST doing a feedhold when power outs. "How to recover from power interruption" in my view is the second part of your problem. "What to do when power is first interrupted" is the first part.

a question: How long can your UPS keep the system running i.e. making chips.

I think this is crucial and will determine to some extent your options down the line.

Ian
Re: How to recover from power interuption?
« Reply #23 on: September 16, 2010, 11:16:13 AM »
Hi Ian

As the UPS is at the moment it should run for about half an hour using the internal battery pack. That should be enough to park every thing. More battery is possible, but, I think it is necessary to maintain holding torque on the motors until power is restored. We have had no power for 26 hours on one occasion; most are for around 8 to 9 hours. The short interuptions; maybe when a baboon has tripped a breaker last only 5 to 10 minutes. For these short interuption I need the UPS to carry the load until power is restored. So, I would not start the park and shutdown routine until the interuption had been in effect for 15 minutes.

Dennis

Offline BR549

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Re: How to recover from power interuption?
« Reply #24 on: September 16, 2010, 11:34:26 AM »
Looking at your accuracy requirements the ONLY way to do this is to run a UPS   "AND " a very large battery bank. That way there is NO interuption of cut.

With your resolution requirement you cannot even "stop" the program without effecting the finish cut. SO the machine must remain running thru the  power outage.

It would be very hard to create a macro to be to retract the cutting bit in a method that would not cause harm to a finish cut. COULD be done but very complicated.

(;-) TP
Re: How to recover from power interuption?
« Reply #25 on: September 16, 2010, 11:42:51 AM »
Thanks for that BR549

It may come to that. Starting to look at using a generator as a back-up for the back-up.

Dennis

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Re: How to recover from power interuption?
« Reply #26 on: September 16, 2010, 01:54:32 PM »
Looking at your accuracy requirements the ONLY way to do this is to run a UPS "AND " a very large battery bank. That way there is NO interuption of cut.

With your resolution requirement you cannot even "stop" the program without effecting the finish cut. SO the machine must remain running thru the  power outage.

It would be very hard to create a macro to be to retract the cutting bit in a method that would not cause harm to a finish cut. COULD be done but very complicated.

(;-) TP

I think you're being a bit "absolutist" here Terry. ONE other way - which kinda kills your ONLY way - is to do what Bivouac has said and incorporate a generator with the UPS.

But I would go further and say that with a bit of thought it wouldn't be be that hard to "park" the spindle, shut down and resume without losing position. The advantage of this of course is that you don't have to then expend on a generator.

I suggested a basic scheme earlier on. I'd be interested in why you think that wouldn't be a reasonable starting point.

Offline BR549

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Re: How to recover from power interuption?
« Reply #27 on: September 16, 2010, 06:49:13 PM »
OK Lets look at the resolution and expected accuracy. This tells me that he is working on extreme detailed parts. AND the time to run tells me it is an expensive part.

I have never seen a machine cutting a finish cut at that resolution that IF you did a feed hold you would not mar, ding, scratch, gouge a finish cut.

Also With certain Material you cannot interupt a cut and have the bit rub the same spot it creates a hard spot which will never finish cut correctly

NOw as the outage events are random we have to assume the worst case senario, it is in a finish cut mode. Experiance tell us IF you plan on the worst case senario the rest will take care of itself(;-)

Try it and you will see what I mean.

 The only way out would be to RUN continuously or wait FOR a point in the program that the bit is NOT cutting material. That could be hours into a long program. The only way to be absolutly sure is to STOP in a tool change senario. OR use built in hold routines throughout the program AND the programs may not  HAVE either.

SO where do you stop????      IF you are just cutting cheap plywood on a router please disregard the above

The generator is just a replacement for a large battery bank same thing only different name. Still a stored energy source(;-) He mentioned a UPS so they need a battery and it is EASY to add more capacity, add more batteries. LONG outages yep he has the answer UPS and a backup generator

Now from past Power company Power Quality Tech experiance you need to run the generator for at least 30 minute AFTER the outage event occurs. AS they bring the system back on line there could be cascade failures that will trip the system back off again. So give the system plenty of time to stabilize before you transfer back to grid power.

As to the stop restart part that would very simple to do ONCE you have the machine stopped. We do that all the time in plasma to stop and check the consumables in long cuts. There is a routine to start restart on this forum somewhere that we use to do it.

That is just my experience in outage recovery technics, Your mileage may vary (;-)
« Last Edit: September 16, 2010, 07:00:23 PM by BR549 »

Offline stirling

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Re: How to recover from power interuption?
« Reply #28 on: September 17, 2010, 04:02:31 AM »
OK Lets look at the resolution and expected accuracy. This tells me that he is working on extreme detailed parts. AND the time to run tells me it is an expensive part.

I have never seen a machine cutting a finish cut at that resolution that IF you did a feed hold you would not mar, ding, scratch, gouge a finish cut.

Also With certain Material you cannot interupt a cut and have the bit rub the same spot it creates a hard spot which will never finish cut correctly

NOw as the outage events are random we have to assume the worst case senario, it is in a finish cut mode. Experiance tell us IF you plan on the worst case senario the rest will take care of itself(;-)

Try it and you will see what I mean.

OK I'll ignore all of the above because these are the very reasons for my suggested approach. Did you read it?

The only way out would be to RUN continuously or wait FOR a point in the program that the bit is NOT cutting material.
More or less what I've proposed. Did you read it?

That could be hours into a long program. The only way to be absolutly sure is to STOP in a tool change senario. OR use built in hold routines throughout the program AND the programs may not  HAVE either.
could be? - may not? - try asking the OP before you right things off. I've always found that an analysis of the problem usually precedes the selection or otherwise of possible solutions - just me from years of software engineering  ::)

The only way out would be to RUN The generator is just a replacement for a large battery bank same thing only different name. Still a stored energy source(;-) He mentioned a UPS so they need a battery and it is EASY to add more capacity, add more batteries. LONG outages yep he has the answer UPS and a backup generator
You only know this because I asked - it was only a few posts ago you ASSUMED it was capacitor based and had less than a second of capacity. Like I said - ask some questions of the OP.

Now from past Power company Power Quality Tech experiance
Ah Terry - is there any job you havn't been an expert in?

As to the stop restart part that would very simple to do ONCE you have the machine stopped. We do that all the time in plasma to stop and check the consumables in long cuts. There is a routine to start restart on this forum somewhere that we use to do it.
One minute you're on about the need for extreme accuarcy and the next your quoting me PLASMA?

That is just my experience in outage recovery technics, Your mileage may vary (;-)
There's clearly no limit to your expertise. I'll get back in my box - Over to you Terry for finding the solution for the OP.

Offline BR549

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Re: How to recover from power interuption?
« Reply #29 on: September 17, 2010, 04:18:10 PM »
AH Stirling if you had only walked in my shoes for the last 40 years.(;-)

Seems to me the OP was asking general questions so he got general answers. Sorry they did not agree with yours.

Capacitor based??? Every CNC i have ever worked on is capacitor based including the computer. SO yes the answer was appropriate. The caps will keep the machine alive for a very short time including the drives. So if you have enought capacity you can RIDE through Blinks and never miss a beat.

BUT without a UPS running you will NEVER have time to capture the positional and program stop data before the caps drain and ALL is lost.

As far as capturing the stop/restart data that is a piece of cake AND I gave an example of what we do it with on a daily basis running a plasma cutter.

nOW is there a type machine I have not used/ ran/ worked on/ rebuilt  NOT MANY. I spent about 40 years in the trenches USING/fixing  those machines. Sorry you missed out on that experience.

BUT I tell you what, you seemed to be a smart fellow I will just sit on my experince and let you handle all the technical parts AS I am probably not qualified or experineced enought to handle MACH stuff after all it IS fairly complicated with all that Gcode stuff (;-)

BUt i would suggest spending about 5 years learning Mach inside and out before you sugar coat and try to convince people that Mach can do anything. It can't it has it limitations. YOU of all people should know that seeing the things you have tried and did not work as you thought it should. YOu need to push EVERY button try EVER code Try every possible combination of code and hardware. Then scratch your head a figure out WHY all teh things that SHOULD work DON'T

Yous guys are a HOOT, and some of the worlds best armchair quaterbacks ,  

Have a good one, (;-) TP
« Last Edit: September 17, 2010, 04:31:49 PM by BR549 »