Protecting the laser Cutter (Electrically)

[Brent Ramsay-Boyd]

Hi All

I am trying to find some info on the best way to go about protecting my laser cutter from power surges and dips.

First of all, I am running a shenhui 80W Reci Tubed Laser. I am trying to figure out my options.

When my laser fires, I have noticed that the lights tend to flicker.

Can anybody clarify which route to take regarding, UPS's, automated voltage regulators. I have seen mention of mains filters and line conditions, but I am not sure what this all means. Is there a way of testing to determine the solution, without buying expensive testing equipment.

I am hesitant to continue cutting until I have the right measures in place, I don't want to have to replace another tube unnecessarily.

Thanks in Advance.

Regards

Brent

[David Somers]

Brent,

I believe best practice for these puppies says you should be on a dedicated circuit. In other words, that is the only device on the circuit. That would be code if you are running it as a 240V device. One 240V device per circuit. But also highly recommended if you are running it as a 110V device. And obviously the circuit and wiring need to be adequate for the load as well.

Beyond that, Something like a Tripplite Line Conditioner would clean up the power coming into the laser. I have had a number of laser manufacturers and resellers suggest that. In Tripplite you will find line conditioners under the Products Menu. Open Other Products and you will see Line Conditioners listed. They have both 110 and 240V products so select the voltage you need. Seems like something in the range of 1000 to 1500Watts is only about $100, give or take. Remember to size it appropriately for the load you will have on it. For example. If your laser has plugs on it for your chiller and exhaust blower and air supply, be sure the line conditioner is sized appropriately for the combined load.

I just got done wiring for an eventual laser and I have a dedicated 220V for the laser, a second dedicated 220 for whatever else comes along that needs it, and 2 dedicated 110 for the perhipherals, plus some network cabling. Overkill, but it was just as easy to pull a slug of cables as 1 or 2. May as well do it while I was crawling about under the house. And now, if I want to connect my 220V screwdrivers to the internet I am ready!!!! Woohoooooo! <grin>

Dave

[Alice Labaton]

Hey Brent,
I'm not sure on the laser side what is going on but you should probably get a simple surge protector, don't need anything fancy. If you're also worried about downtime/uptime, get one of these -- http://www.apc.com/products/family/index.cfm?id=29
Batteries last a very long time and APC makes the best in the industry for backup units.

[Mike Null]

My machine is 110v on a dedicated 20 amp circuit. Dave is right--don't run other things on your laser circuit.

[Art Mann]

If the main symptom is that your lights are dimming when the laser is activated, that is a sign that your wiring is inadequate. It has nothing to do with power surges. I doubt if inexpensive filters or power conditioners will do anything to help. As some have said, what you need is a different circuit with adequately sized wire for the load and distance from the breaker box.

[David Somers]

Alice and Brent,

APC is an excellent company, but I don't think a UPS/battery will help you? At least I have never seen a UPS suggested as a useful protection for a laser. Typically you rely on a UPS to get you far enough into a power outage to let you shut down gracefully. I have a feeling that between the draw of most lasers, and the length of time a job needs to run you might be into such a large capacity UPS that it is wicked expensive. Ask your vendor or tech support though. I could easily be misinterpreting the way these things work.

Brent's issue sounded more like he is on a non dedicated circuit and the draw from his laser is reducing the voltage to the other devices on the circuit, his lights for example, which were flickering. Putting it on a dedicated circuit would fix that.

A surge suppressor will protect the machine from spikes in voltage, but won't condition the incoming voltage if it is changing up and down. A line conditioner will make sure the output voltage stays constant regardless of the input voltage, to a point of course. A line conditioner will not protect against a power outage like a battery/Uninteruptible Power Supply will. As I said though, I think a UPS is going to have to be sized so large for a laser and the way they work that it would be too expensive to bother with for the average business.

Probably the one time I could see a UPS being used on a laser might be if your power sucked big time and you suffered outages on and off through the day. A UPS could get you through a short outage if it is sized right. Or, if you had a generator that kicked in during an outage and kept your facility going a UPS could see you through the brief period between the actual power outage and when the generator is on line. I am not sure how many laser operations would see the need for all that however. You would have to balance any loss of materials due to a job in progress failing against the cost of the UPS. I don't know if it would be worth it?

One of the offices I used to cover when I worked out in the Pacific Islands was Saipan. Outages were very common there throughout the day. We had a generator that could cover us during an outage, and our UPS's kept critical things running through that brief period between the actual outage and the generator taking over. Our UPSes were covering things like computers and phone systems and routers and switches and whatnot however, not shop equipment.

So...I might suggest a dedicated circuit as your first effort. And if you find after doing that you still need more protection get a line conditioner for the laser.

Dave

[Michael Hunter]

If you go the UPS way, you need a BIG one!

Firstly, find out what power your laser actually draws : I would guess about 1.5kW when it is working hard, but it could be more.
The cheap meters for checking general power economy are fine for this - it doesn't need to be amazingly accurate. I paid £10 (~$15) for a meter in the UK.

UPS output is normally given in VA (Volts times Amps) : divide the VA figure by 1.4 to get the output in kW.

Now look at the UPS catalogues. To really help, you need the double-conversion type which conditions the mains continuously.
Big input of breath through shock! The big-name brands that will do the job are really expensive.
So look at Ebay : I got a brand new 2000VA dual-conversion unit for £200 (~$300) and it has given good service for about 6 years now.
For my 60W Epilog, 2000VA is only just enough : if I raster on full power for more than about 20 minutes it starts beeping to complain. For ordinary jobs it is running at about half power which should be fine for years.

A UPS won't necessarily stop the lights flashing, but at least you can turn other high power things (like heaters) on or off without worrying that the voltage change will upset a running job.
The hold-up time won't be long - probably only a few minutes - but that might just save a job if there is a power cut.

[Bill George]

Art has got it correct. If your lights are dimming a UPS is not where to start. Start with your main service, how many amps 100, 150 or 200 and what is really the load on that service?
Is your laser on a dedicated circuit and what size wire. A 20 amp breaker on 120 volt line and #12 copper wire with a ground wire. Perhaps you need a 30 amp circuit on #10 wire?

[Keith Colson]

Here are a couple of rules I live by. Always unplug the laser from the wall if there is a storm. Surge protectors wont help in a lightning strike, they are just not fast or powerful enough. Always leave your machine plugged in at the wall when not in use. The 2 watts or so they use in standby keeps a little heat in there to deal with moisture. The extraction fans do promote condensation.

If your lights are dimming you can measure where the voltage is dropping with a volt meter. This is where 220 volts is so much better. Double voltage means half the current so less loss in the cables. Try to avoid extension cords too. If you do use them then make up some high quality ones.

Cheers
Keith